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CrossBow

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  1. CrossBow

    The curse of the Saturn horizontal lines!

    By CrossBow,


    Service Work Stories
    This story starts a few years ago when I powered on my model 1 Sega Saturn and played a game for a bit and then powered the console off and back on to switch to a different game. But to my horror I discovered some strange horizontal white lines scrolling upwards on the screen? I powered the console off/on again and the lines were still there only now there were a lot more of them and they were scrolling much faster. Additional power off/on cycles would only cause the lines to change thickness and motion and scrolling rate. I don't have a picture of my actual console doing this, but here is one on youtube that demonstrates the issue very well. It is best to see it in motion anyway to get an idea of how annoying it really is..
     
    Reading up on the issue you find a few different fixes for the issue or no fixes at all. The most common fix thought to correct it, is to replace the caps in the PSU board. Saturn consoles have their PSUs internal inside them. Luckily they are all throug hole caps to not that big a deal to replace. But you have to make sure when ordering a cap kit, that you order the right one for your Saturn as it seems there over a half dozen different PSUs used on the various Saturn models and they all have different component layouts, different amount of caps needed, and of course different values of caps used. So that was the first thing I did was to recap my PSU. And at first I thought things were good... but nope. The issue would happen after about 10min of playing a game and when powering cycling the console again to change games, the white lines would be back?! Keep in mind the actual console continues to play normally but visually it is less than ideal.
    The next common fix for this issue that has worked for a few people, is to replace the main PWM switcher that is on the PSU boards. There were two main types used in the Saturns depending on the country it was being used in. For instance in Japan and NA. The PWM could handle between 100 - 120v. In Europe it was for their 220-240v ranges. The exact PWMs used are difficult to find but I did some sleuthing on this over a year ago and found a modern drop in replacement that can be used in all regions as it can handle between 100 - 240v by itself. These can be purchased from console5 if needed here:
    https://console5.com/store/top224yn-saturn-power-supply-pwm-75w-voltage-regulator-replacement-for-top102yai.html
    But sadly once again in my case, it was not to be the fix for mine. So I've just kinda lived with the issue now. Until last night when I remembered something and then tested it a bit.
    Remember when I said that powering off/on would cause the lines to be different each time on my console? Well, I also discovered that if I could quickly turn the console off/on enough to cause the screen to dim for a sec but not enough to cause the saturn or the game to actually shut off, that sometimes those lines would go away?! That got me to thinking... which, in all honesty can be a bad idea for me sometimes.
    The power switch changes the conditions depending on how quickly I'm actuating it. Or maybe the force used to power it on and off? So...
    I decided to take the switch apart. This was NOT an easy task. The switches used on these earlier model 1 units I believe are different than later made models. It has an additional power protection component soldered onto the AC input wires on the side of the switch. Wrapped with a bit of yellow electrical tape, and then a blue/green translucent colored rubber cap that was draped over it to protect everything. Once you carefully remove all of this (As you will want to reuse at least the rubber cap). Then you have to pry apart the steel housing that covers the top portion of the switch. Once you have done this, you have to be careful of 2 things. Both of which are springs that will do what springs do best. They will likely shoot out somewhere and you won't find them again if you aren't careful. My wife may or may not have a non functioning ball point pin in her pen holder as I type this...
    Once I got this figured out and was able to study the switch. I then found old yellowed colored grease inside the switch along with a bit of black carbon residue mixed into the grease. Similar to what we see on colecovision and atari toggle switches. I cleaned all of this gunk out and put it back together with some new dielectric grease. Once I got that switch back together. I crossed my fingers and turned on the Saturn. No white lines! But I couldn't get excited about it just yet because what I didn't mention is that most of the time on the first power on, the Saturn doesn't have those lines. It is only after it has been on for a bit and then I power cycle it that the lines would appear. So I played some Bulk Slash and got through a few missions and powered the console off to switch games. Turned it back on... and still no white lines?! This is a good sign. I continued to play several different games for at least another hour and half power cycling the console well over a dozen times in the process and those pesky white lines have not come back.
    So it would seem that power switches are another potential source for the white lines issue on Saturn consoles. I'm not sure why the first power on would always be good and it was only successive power on attempts after that would cause this, but for now it seems those issues might finally be corrected. I will have to play a bit more Saturn games to find out. What a chore... 😉 hehe.
    Here are some pics of the insides of my Saturn for those that might be curious. I recapped the entire thing several years ago and at the time only radial caps were in the kits so I had to install them in a similar manner to how it is done on Gamegears when replacing surface mount like caps with through hole radial type. And, it has a Hi-Saturn region free BIOS installed as well. Even with the Rhea configured to report every game as being NA/US, the Japanese games still wouldn't load right and would require me to use my Acton Replay cart to bypass. But as that cart becomes more and more finicky to use, I opted to just install the region free since in this model Saturn, it is literally a drop in replacement chip.

     

     

  2. CrossBow

    The Ivory Tower 5200 got some TLC

    By CrossBow,


    Service Work Stories
    I originally did most of the work on this 5200 about 8 years ago. It was also one of the first projects I did and to be honest, the wiring work inside wasn't that great. For some time I had wanted to redo it all similar to how I redid my 7800 about a year ago but just never got around to it. Well, now that I have a new BackBit Pro flash cartridge and it was designed to allow resets back to the game menu, I felt it was time to perform a small modification to allow this function of my BackBit Pro to work and also decided it was time to redo the wiring work and give my 5200 a much needed bath.
    So first I will share some old pics of when I first AV upgraded the console. The wiring wasn't that bad I guess but it was before I was using better quality wire and wasn't using connectors so it was all tethered down. Also, not long after this was first done, the s-video jack kept coming loose on me so I had to hot glue it into place. No pics of that hot snot but suffice to say it was pretty ugly. 

     
    Here is another shot showing how all the wiring was done originally in this setup. 

     
    All of the wiring was completely redone with better quality wire and using install methods that I've been using on client consoles for the past 5 years. 

    Some of the wiring was to redo the power and ground wiring as I now have it attached to the main power and ground rails that run along the middle of the board. As a result they are much shorter than they were previously. All the of the video output wiring was redone with a connector added in the middle to allow for easier removal of the main board in the future for servicing if needed. A connector was also added to the power modification wiring on the bottom side as well. 

     
    A new s-video jack was installed as the original was in pretty bad shape from coming loose over the years and the hot glue just had to go. I used my dremel to rough up the area around the s-video jack and shave off a little bit of shell material so that I could install a new s-video jack and have the back nut actually secure it into place properly. Last to ensure it stays put, some epoxy was added around the s-video jack and securing nut. Audio wiring was redone as well and cleaned up.
    Finally a small bit of wire was added on the bottom side of the PCB that attaches the reset line for the system to an unused pin on the cartridge port. The BackBit Pro flash cart is designed to take advantage of this and with this wire in place, I can now use the reset button on the cartridge to take me back to the game selection menu. This is a feature that is sorely missing on the AtariMax carts as they require hard powering the 5200 console to get back to your game menu selection. 

     
    At the end, I finally gave the case shells a much needed bath as it had been at least a decade since this 5200 had been cleaned. It was getting pretty dusty in those vent slots and just looking a bit dull. Now this 5200 is working better than before and ready to provide some more 5200 gaming for many more years!

  3. CrossBow

    Atari 7800 :- Controller remote pause function modification

    By CrossBow,


    Ivory Tower Technical Info & Notes
    This is something I've messed with on and off again over the years. After I discovered the controller pause modification you can do on the Sega Master System, it got me to thinking if something similar was possible on the 7800. And yes, it totally is as similar to the SMS, the pause line on the 7800 is always active and only when pulled low to ground does it trigger the pause. So I had played with it a bit using home made perfboard setups etc. But it wasn't really as useful or needed on the 7800 as it is on the SMS so I hadn't really invested much into it.
    For those that might not be aware, the Master System also uses a 2-button controller like the 7800, but the SMS also has a pause button on the console itself just like the 7800. The difference it that many SMS games actually use the pause on the console as a 3rd button to pull up inventory or stats..etc. in quite a few games. As a result, playing those games can be a bother when you have to get up and press the pause on your console each time you want to access those extra functions in the game. So naturally a modification for the SMS was going to come about to allow a person to add a 3rd button to their controller and along with a simple logic circuit in the console, you can make impossible controller combinations trigger functions inside the system. In the case of the SMS it is using an extra button to trigger either an Left+Right direction combo, or Up+Down depending on how you wire it up. That in turn is fed to a logic OR gate so that when you press that button on the controller it sends that impossible combination to the chip and that in turn will trigger the reset function. 
    The 7800 sharing essentially the same setup here can also be done in the same manner. However, due to the 2600 and 7800 internal logic regarding the paddles controllers; you can't use the Left+Right combo because it will confuse the console and sometimes thing paddles are plugged in. But aside from that, it is the same. 
    Consoles Unleashed in the UK sells a lot of excellent quality modification and upgrade kits for various consoles. One of those they have the most kits for, is the Sega Master System. They provide their own pause button modification kit that is really well made and looks nice. Well, I ordered up a few several weeks back and got them in yesterday. I immediately went to work on installing one into my personal 7800 as I have 2 controllers that I've modified in the past to be able to use this setup. Here is what that looks like:

    As you can see it is a tiny PCB that will fit in lots of places on the 7800 main board. Again, it is designed for the SMS but will work just as well in the 7800. In the pic above you can see that I'm getting power and ground from the bypass cap just to the right of the 6502. The Player 1 Up and Dn connections are at the top of those two resistors right next to that cap. So you have half of what you need right there in that spot. 

    Above is where the rest of the connections in my setup are going. The small blue wire that runs by itself to that single point below the RIOT IC is the reset trigger. This is an unused via that is present on every single 7800 main board revision I've see and always in this same spot. I assume it was there for testing but is also makes a great place to attach the PB pad from that board to trigger the pause function. The other two blue wires are going into cleaned out unused vias so they pass back down on the bottom of the board to attach to a similar set of resistors for the player 2 Up and Down connections. I did it this way because I didn't want to trim the RF shielding. The resistors are outside of the shielding for the player 2 controller port next to the Reset switch.

    And this is where the two wires come back through to the bottom of the PCB to attach to the resistors mentioned above. BTW, the Up and Down combo wiring attaches to Pins 1 and 2 on the controller ports.
    And that's it! Now with this in place, I can use my modified controllers to remote activate the pause on the 7800 console from either controller port.
    One thing to mention about using this kit from Console's Unleashed...
    You have to wire both controller ports! The reason is because instead of using an OR logic in this setup, they are using a NOR logic chip. As a result, the controller ports are always registering high. If you don't connect up the second set of wires, then the logic on the pause board in the kit ends up triggering the pause constantly. It needs to see that +5 from the port pins in order to maintain the logic. So if you only wanted one port to activate this, you need to use a different logic IC. Also, the kits from consoles unleashed has extra stuff I don't normally need as it comes with additional small PCBs to mount a 3rd button to and provide as a template to drill the hole into your SMS controllers for mounting it. An excellent touch to be sure, but I don't like the SMS control pads compared to other controllers and wouldn't be using them on a 7800 anyway. But they aren't that expensive and I might need those boards in the future so who knows? I might go into details on what is required on the controller side someday for this modification to work as there is work required in the controllers. I think I've covered it elsewhere online but might do that as a follow up someday.
    Here is a link to Consoles Unleashed in the UK and again, they have some excellent quality kits on hand to help modders and tech with making their projects look that more professional and easier to install.
    https://www.consolesunleashed.com/
  4. CrossBow

    Loctite and ABS = Gallium and Aluminum...

    By CrossBow,


    Ivory Tower Technical Info & Notes
    So over the past few months, I've been trying to find ways of making the RCA jacks that I install into consoles more secure so they don't free spin over time. What I've been doing in the past that actually works 90% of the time far as I know...is that instead of using the small lock ring washer that typically comes with RCA jacks, I use inner star washers of the right diameter to do the same thing, but with more points of contact to lock into the plastic. It also has the advantage of holding the securing nut in place tighter as well since the inner teeth of the washers are present on both sides of the washer. From there, I've used light amounts of epoxy to help hold the securing nuts fast in place as well. 
    This has worked well for years but recently I did have some consoles start to come back where one or more of the RCAs had still somehow managed to work loose over time. So this got me to wondering if there were other methods I could employ. 
    Enter the idea to use Loctite or something similar... Hang tight...there is some history I have to talk about first and a lot of details to follow. Grab a snack and drink and settle in...
    Now there are two types of loctite that you can get for threading applications. One is the red colored stuff and is essentially permanent in that it is very very difficult to remove nuts off their threads if that stuff is used. The other is the blue kind that still allows the parts to be separated (Although not nearly as easily as without...). So I decided to try the blue stuff.
    Now I will say that sure enough the blue loctite holds really well. It basically is a liquid that once exposed to air begins to congeal and turn into a rubber like substance. As a result, it acts as filler between the threads of the nut and the jacks you are securing together. It does still come undone but requires a lot more force to do so and actually squeaks while you remove the parts after it has cured. So it does its job... but... there is also a warning on the package that I did read but didn't think would be an issue in this case.
    The warning says not to use with plastic threaded parts. So I assume this meant not to use it with plastic bolt/nuts sets commonly made of Teflon and the like. Well... I'm here to tell you that isn't the only issue.
    Over a month ago, I installed a UAV into an 800xl. The owner requested I install a separate standard 4pin s-video jack in the opening that the RF modulator used to occupy as the opening is nearly the exact size needed for one style of s-video jacks I have on hand. But they also wanted a pair of RCAs for audio to be installed. They didn't want to purchase an Atari monitor cable specific for this hence the request for separate jacks. So I drilled in the needed holes and got the jacks line up great! To install them, I used a bit of the loctite on the threads of the RCA jacks and proceeded to tighten everything up as normal. I then set the case shell down for about an hour while I recapped the main board and did other things. When I picked up the bottom shell housing I was horrified to see that a long crack had formed between the two RCAs that ran beyond top to bottom of the shell?! I removed the RCAs and discovered that around the holes where the jacks had been installed, there were small spider cracks around the openings and the plastic appeared to be much more brittle than I remembered? So I cleaned everything up and applied some epoxy across the cracks on the inside of the case shell to restrengthen the area and prevent any further cracks from occuring. I let it cure for about 2 days before reinstalling the RCA jacks. This time as they already had the loctite on them, I didn't apply anymore and just had to crank down a bit more to tighten them back up. This time I left them a little more loose than normal and then applied more expoxy over everything to make sure it all held tight. And this worked fine as expected.
    My thinking at that time was that I had simply tightened the nuts on the RCA jacks too much and it caused stress fracturing in the plastic that spread out. Didn't think much of it beyond that.
    Last night while working on a 5200 (A console I've done this work on a LOT of times), I drilled in the holes on the expansion plate as normal using a template I've had for years now. Installed the RCAs and again used some loctite on the threads to secure them nicely in place and then set it aside for about 30min while doing other things. I picked it back up to solder the wiring to it and again was horrified to see a crack had formed vertically between two of the RCA jacks?! I was like, what the heck?! I've done a lot of these 5200s and the expansion plate has never done this before? When I started to remove the RCAs to inspect, the entire thing just started to crumble in my hands like dirt. Sure enough the entire plate had become super brittle and was falling apart in my hands?! At this point I was pretty sure I knew what was happening and decided to test on another piece of similar plastic. Scratched it to expose the inner plastic and applied a little loctite. Yeap... that little piece of plastic became a brittle mess within about 15min of application.
    So.. the lesson here is that Loctite chemically reacts with ABS plastics and causes the ABS to breakdown at a molecular level in a very similar fashion to that of gallium when put in contact with scratched aluminum. Going forward, I'm just going to have to stick with my star lock washers and epoxy it seems...
     
  5. CrossBow
    As some might know by now, I've got an MT-200 that I picked up over a month ago now. Really cool little device from Roland that was originally intended for use in teaching music. But these devices have the ability to play back midi files through built in disk drives that use IBM formatted 3.5 inch disks. They can also be used as sound modules and with modern day computers can still be made to be used with ScummVM and Dosbox for classic gaming. Anyway I was getting frustrated with my disks seeming to work one day and then a week later suddenly given me read errors. So I read up on using one of these cheap Gotek floppy emulators into mine. But information on actually making one work with my MT-200 wasn't to be found. I did find Gotek's pre-configured to work with devices like my Roland MT-200 and its variants on eBay, but at $80 + shipping that seemed crazy to me. So I bought a generic Gotek with the intention of figuring out how to make it work in my Roland MT-200.

    I was quite successful and it turned out to be MUCH easier than I thought it would be. I did a video last week on the process of which jumpers are needed, the installation, and the software I found to make it all work in my Roland MT-200. I now share this knowledge in my recently released YT video so that you don't have to pay those crazy prices on eBay either and can hopefully find this useful:


    View the full article
  6. CrossBow

    Just a simple but kinda cool project?

    By CrossBow,


    Ivory Tower Technical Info & Notes
    The 'Tower' was without power most of last week due to powerful storms on Father's day. As a result it put me behind a bit on console services and projects. Well last night as I've been working kinda constantly on console stuff to try and get caught up, I took a break and decided to do something I'd been meaning to try and implement for a while now.
    I'm sure many of you here are aware of the Atari Vox? In summary it is a small device that plugs into controller port 2 on the 2600 or 7800 systems to allow you to save game scores and can also provide a means for speech to be played back in games that support it. Very cool device but it has one annoying thing about it. That is the fact that the audio from the Avox is separate from the rest of the system so you either have to plug in a set of external speakers or as I had been doing, I would use a 1/8" to RCA cable and plug one of the RCA jacks into one channel (usually the right) on my AV receiver audio input and the 7800 audio out in the other channel. Or, you have to use an external audio mixer to combine the two into one. None of that is really elegant so I thought of a simpler way to go about it. I'm sure you can see where this might be going?
    So the 7800 especially is a little unique in that it was designed to make sure of an external audio input from the cartridge port. Typically POKEY enhanced games use this for audio. The basic mixing for this in the console is to tie the TIA audio coming in internally from the console's TIA chip and the POKEY audio from the external cartridge audio input line with different resistors for each to balance their signal so that one doesn't overpower the other. Well, why not simply add in a third audio line into that mix with a resistor to also bring it down in level?
    That is exactly what I did as is demonstrated in this video...
     
    I have some pics I can provide for those interested but in a nutshell I installed a separate 3.5mm audio jack along the back of this test 7800 I have in the ITC lab and instead of if providing audio output, it is used as an audio input and is part of the mix along with the external audio and internal TIA audio. This allows for all three to be used at once and have all the audio could out through my normal audio output RCAs I have installed on the console. 
    No separate speakers...not Atari audio from just the Left with the AVox speed only on the right. It is all properly mixed together in dual mono as I would prefer. I will next do the same on my actual daily driver 7800 where this would be used most, but I'm glad to have it on my lab 7800 as well. The way this was done, should also be possible on a 2600 and I might very well explore that on a 2600jr I also have in the lab. 
    I know this isn't the first time something like this has been done as I've seen other projects where owners have embedded the AVox completely into their consoles and then with a lot of wiring, use a switch to enable/disable the Avox as needed. But I was looking for a more simpler solution that would still allow the AVox to be used with multiple consoles and not be gutted and dedicated inside a single system and yet still easy to use without a lot of extra wire and mess. One small headphone to headphone patch cable is all that is needed now for this when I want to use my Avox.
    For those that might want to try this on their own, know that a limiting resistor is needed as running the audio output straight in from the AVox is likely to sound messed up/distorted and would cause audio cut off on other audio sources trying to play at the same time. I used an 8k resistor in my test here but I think anything between 6.8k - 10k would suffice. I would also start with your volume pot on the AVox set to about the 1/3 volume level and then play a game that uses both speech and other audio at once to dial in the volume on the Avox until you are happy with it all.
     
  7. CrossBow
    This might require its own thread but I actually was working on an NTSC 7800 that was eating my lunch most of the weekend. It was sent in for just a basic composite mod installed into it. When I used the diagnostic roms everything was fine with this 7800. But then not long after I got the composite board installed and tested it again, I noticed some odd flashing lines of colors across the screen. It seemed to do this badly on Dungeon Stalker and Ballblazer. In the case of both games, it would flicker around with the color like this for anywhere from a few minutes to about 10min and then just abruptly lock up or got to a black screen?! It was also doing it through the RF when I put everything back in stock condition and reinstalled the original components I had removed. I replaced every single one of the main ICs without any luck starting with the Maria as it wasn't doing this in 2600 games. I did try to install my cap off the A15 line in a similar fashion as my other video I did about this,  but that didn't change anything either. You know what removed 90% of the flickering color bars on the screen and stopped it from locking up?
     
    The freaking crystal! (Y1) I removed the one in it and replaced it from one of my 2 parts donor 7800 boards. The first one I popped in the flashing colors were only occasional on the game ballblazer but didn't happen at all with dungeon stalker or any other games I tried. And more importantly, it didn't lock up either and BB and Dungeon Stalker both ran for several hours before I finally shut them off. I did try other crystals to see if I could get the slight flicker to go away completely but that only took it back to the way it was. So obviously something in the crystal I installed from the other 7800 seem to mesh better with this 7800. I also replaced every single one of the 3904s starting with Q3 and Q4 as both of those were installed. In fact this 7800 was kinda strange. Seem to use a later revision board, had C64 for the extra timing circuit on it, but was missing the rest of the ICs you usually find in that circuit? It also had all of the caps and resistors installed, whereas most of them show some removed at the factory by clipping them out or just not being installed in the first place. It also was using Sony 10ns speed RAM in it but no resistor installed on the bottom RAM chip as I normally see with most of the Sony RAMs. (BTW replacing RAM didn't do anything and in fact just gave me a black screen).
     
    So all I can say is that timing on the 7800 doesn't have much room for tolerance it seems and that all of the components we find installed into the consoles was done so at the factory in what seems like a case by case basis? 
     
    BTW when I put it all back together and replaced all the RF shielding, the flickering seemed to go away completely at that point? I'm still not 100% sure it is 'fixed' but it is a strange issue for sure and one I hadn't yet come across.
     
     
    View the full article
  8. CrossBow

    IMP TIA = BAD TIA!!!

    By CrossBow,

    Had a pre-modded 7800 sent to me with a UAV that had good s-video but was producing some ugly jail bars in composite. But it was ONLY doing this on 2600 games. I at first suspected something in the wiring of the UAV or the UAV itself and first redid all of that and replaced the UAV. No change. It was then I started to look at things more closely and noticed that this '84 main board all socketed chip board appeared to have a TIA I'd not seen before. The company branding on it is IMP and it had a mid year 1988 date stamp on it indicating it was not likely original to the 7800 to begin with. Since I was able to disconnect the TIA color signal and get crystal clear black n white with the jail bars, I knew it had to be in the color signal. And since the UAV is tapping that signal straight from pin#9 off the TIA there was really only one culprit. I had another semi working 7800 with a more normal looking AMI branded TIA on it. Pulled that and put it into the socket on this troublesome 7800. Sure enough the jail bars are gone! I'm guessing this is a late revision TIA and it likely a CMOS part as it doesn't seem to heat up like most TIA chips do and it just feels a bit different. In any event...stay the hell away from these TIAs in and think about replacing them if you find them in your 2600s or 7800s. Especially if you plan to use composite upgrades or a UAV as it does produce jail bars. I also noticed that color trimmer has to be adjusted but a full 180 between the two chips. So there are some obvious internal differences in how they are designed and made. I've attached some pics to show what I was getting and between the two TIA chips.
     
    Here is the section about halfway on the edge of the ColorMatch screen on the Colorbar generator program. You can see the jail bars on the slightly different hue of green on the lower half. Upper half is fine.

     
    Here is the green purity screen with the bad TIA. Again, you can see the jail bars and while this is on green, they are present on all colors pretty much.

     
    Here is the colorbar screen from the bad TIA IMP branded chip. Again you will see that most of the colors exhibit noticed jail bars on them. It is quite distracting and unusual to see from a UAV board.

     
    Here is the actual IMP branded TIA chip that was causing the headaches above:

     
     
    Now here is the colormatch screen edge with the good AMI branded TIA chip.

     
    Here is the green purity screen with the good working TIA. Quite a difference here.

     
    Here is the colorbar screen on the AMI TIA. While there is still come color bleeding and other artifacts normal with composite on an LCD, you will see that the colors don't have the jail bars as they did with the other TIA chip.

     
    And of course, this is what the common AMI branded TIA looks like in most 7800s I've encountered:

     
    So if you have nasty jail bars from your composite video out signal, you might look at the TIA as the possible cause.
     
    Ivory Tower Collections
     
    View the full article
  9. CrossBow
    In this 3 video series, I go over the basics and understanding of the Roland MT-200 sound module. It is an excellent multifunction sound module that can act as both a sequencer and sound module. This means that in addition to being a very nice general MIDI and Sound Canvas sound module, it also has the ability to record MIDI songs from the MIDI in port and save them to diskette to be played back in a standalone fashion later, making it a MIDI Jukebox as well!

    The first video goes over the basic overview of the module itself in what it is, what it can do, how to access the hidden diagnostic functions, and their uses.







    In the second video I go over the advanced diagnostic functions in how to set the internal date and time along with how to use the diskette drive functions.





    In the third and final video in this series, I go over the basic hardware needed to connect the MT-200 for use on a modern day computer. I also cover how to get the software drivers along with how to configure ScummVM and DosBOX for using an external MIDI device. Finally I demo how I have my MT-200 connected to my modern day Windows 10 PC along with my Roland MT-32 connected through MIDI Pass-thru. I then demo how I use the two modules in DosBOX on the game Space Quest 1 (VGA Remake). The audio is heavily compressed on this part as Geforce Experience software compresses the audio to mad levels for streaming. But you get the idea on how it works all the same.




    Thank you for viewing these as it has been a lot of fun learning about this wonderful sound module and understanding its uses and secrets! Enjoy!View the full article
  10. CrossBow
    Been doing a few composite AV mods on client intellivisions. Though I would video the process I go through for doing a capacitor replacement. I'm working on trying to get the videos down to be more watchable in smaller amounts of time but perhaps too much compression on time is used in this video?
     
    Big special thanks to Adan Toledo for his permission to feature some of his music from the CollectorVision homebrew release of Sydney Hunter & the Sacred Tribe for the Intellivision!
     
    - Order your official OSTs for Sydney Hunter and Mecha 8 from Adan himself here: http://adan.eu5.net/europe.html
    - Order your copy of Sydney Hunter & the Sacred Tribe plus other homebrews from CollectorVision here: http://collectorvision.com/
     
    Comments always welcome and much appreciated!
     

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  12. CrossBow

    Sega Master System - FM upgrade Region Switch Info

    By CrossBow,


    Ivory Tower Technical Info & Notes
    I've installed the FM upgrade board 4 times now into a few different SMS NTSC consoles now and something that I tend to always forget, is that the official instructions for installing the board has a few mistakes in it. One of those mistakes is a pretty big one that I've mentioned to Tim Worthington a few times but it never seems to get fixed in his guide. That step is regarding the process for getting the region switch working on NTSC consoles. Now the steps listed I'm sure are accurate for PAL versions of the console, but 3 different model 1 and one model 2 unit I've installed the kit into all required the same thing to get it working.
    The specific step to install the region switch wire states to solder a wire from the IORQ pin off the FM board and to isolate and solder the same signal pin on the 2516 IC chip in the console. This chip is the IO Gate array IC btw. The docs state this is pin 19 on that IC and that is a correct statement. However, removing this pin from circuit on the NTSC consoles will prevent the SMS from booting at all. Just a black screen when powering on the console. Attaching the region switch wire to that pin while isolate does nothing.
    The pin you want to attach to instead on that IC is actually Pin 23. It is listed as the KillGa pin and I assume has something to do with a halt or reset. In some models of the SMS pin 23 isn't attached to anything. But on the NTSC systems it is part of the circuit. So, you have to either cut the trace to this pin or lift the pin from the board to isolate it and then install the IORQ wire from the FM board to pin 23. This will correctly allow switching the region on the SMS. The region switch isn't dynamic so you have to either reset the game after switching, or power the SMS off and then back on for the region switch setting to take effect. Here is a picture of the wire I'm talking about attached to a lifted pin23 off the IC I did the other night as an example.

    Here is the IORQ pad the other end of the wire attaches to on the current and latest version of the FM board upgrades. Depending on the version of the FM you have, this pad has changed places but it is always labeled the same. In the pic below is the yellow wire soldered on the upper left section.

     
    So if you ever install one of these or possibly have one installed and hadn't gotten the region switching working on your NTSC console, now you know why and how to correct for it.
    BTW the switch is advised because it allows you to select between US/PSG audio, US/FM audio, and JPN/FM audio settings. There are 2 games known that require the JPN/FM setting in order for them to work with the main one being Wonder Boy III: The Dragon's Trap here in the US (Wonder Boy II in JPN).
     
  13. CrossBow
    Not a video to share this time, although in hindsight I should have made one as a quick tech video. But recently I decided I would get some replacement filter caps for use in standard wall wart power supplies like those used with our Atari, Sega, etc. consoles from back in the day. As I have quite a few of them on hand and wanted to test them out I decided to start with a few Sega Genesis power supplies. I decided to look at three different supplies last night. I first checked the voltages from all of them and they were all pretty normal. One reading about 14v, a model 2 supply reading 13.5, another model 1 reading about 13.8v. Nothing out of the ordinary from such old transformer supplies that don't have a load on them. Still, they are all well over 20 years old so I figured why not.
     
    Now, many of the sega power supplies require a small 4mm hex bit to open them up and that was the case with one of the model 1 supplies I had. I didn't have this tool so I ordered it online. The other two I had actually required a small #5 security torx bit similar to what is used on TurboGrafx and PC engine systems. But that bit I had on hand and with that I was ready to crack them open and get to work.
     
    The first model 1 PSU is one I've been using for a few years on my workbench as a go to PSU for several systems. I've created adapters so that I can use it with several other classic consoles I work on so I don't have to keep a bunch of different ones on hand at the ready. So it has gotten quite a bit of use over the past few years. It required the small 4mm hex bit I had to order. No issues once I got it opened up. Looked okay and had that ages electronics smell but nothing out of the ordinary. Removed the old large 3300µf at 16v capacitor. It seemed to be in good shape still with no evidence of bulging or leaking. Still it is over 20 years old and would hurt to change it out. Did that and working just dandy!
     
    Then I looked at the second one and this one is where I first discovered that the 4mm hex nut driver I'd gotten wouldn't work and I needed to use my #5 security torx instead. Opened it up and it noticed it seemed to be glued shut as the two halves wouldn't separate as easily as the last one had. Interesting..worked on it a bit and was able to get it to come loose on one side. It was right about when I started to grab for a small flat blade screw driver help pry open along the sides that the smell hit me... 
     
    If you aren't aware, the old electrolyte used in these older caps smells very much like fish and has an oily consistency to it. And it is very distinctive and not at all like a normal electronics type smell. This wasn't a good sign as that smell would indicate that I was about to discover something nasty inside. Once I got the two halves of the PSU case apart, the smell really hit me and I could see it. A shiny surface on the top of the small PCB around some of the diodes on the PSU and where the output wires are soldered in. I removed the PSU assembly from the case housing and this is what it looked like on top.

     
    Now it is hard to see, but you can make out the shiny look on the PCB and also where it is a darker color. But the large filter cap looks okay physically right?

     
    Well not quite because once I removed it you can see near the negative lead of the cap, where it has stained the PCB from electrolyte that has been leaking from the capacitor over the years. Also hard to make out but the bottom of the cap itself was also coated in the oily residue of the leaking electrolyte. Now this doesn't seem like a big deal right? Just clean that off and put in a new cap and your good to go? Well, the bottom side of the PCB where the traces are, has a very different story to tell and shows you the results of what leaking electrolyte does on a PCB over time.

     
    Here you can see where there is a mottled almost moldy look the left half of the bottom of the PCB here. Well, that is where the cap was and where the electrolyte over time has seeped onto the bottom of the PCB and started to corrode the upper layers of the PCB masking and copper traces under neath. This is essentially cancer on a PCB slowly eating away at the board. If this had been something with much smaller traces to components, it would likely be a lost cause or at least require quite a bit of small and time consuming trace repair work. Luckily the traces on most PSUs like this are large and thick. So how do you clean this up? I took my electrical grade 99.9% alcohol cleaning solvent and a toothbrush and went to work to clean and neutralize the electrolyte. In the process of this, the top green layer coating started to flake off exposing the copper traces underneath it since the electrolyte had so badly ate into it. There were also dark patches on the copper itself underneath. This required me to also use my fiberglass pen to remove the remaining layer protecting the traces to fully expose them and also remove the corrosion. This is what it looked like after cleaning and removing most of the corrosion.

     
    Still a few dark patches left behind that has pitted into the copper traces but it shouldn't get any worse than it is now since it is cleaned up. So what now? Well I installed the new replacement filter cap and the used lots of flux and solder to apply a new layer across the traces to protect the copper underneath going forward. This was following up by a lot more cleaning with both a PCB board spray cleaner and lots more high grade alcohol. I then left it out overnight exposed to fully dry out before testing and reassembly.

     
    The third PSU was for a model 2 genesis and also required the #5torx security bit to open it. It was like the first PSU in that the capacitor in it wasn't leaking and everything appeared to be fine inside. Just replaced that cap the same way as the first, buttoned it back up and it works just fine. 
     
    But the moral of this is that just because a power supply works, doesn't mean that everything inside it is okay and good to go. That second PSU with the leaking cap would have eventually died on me as the traces would have continued to corrode and eventually sever from the rest of the circuit and possible start to lift from the PCB itself. This means that with this wonderful discovery, I need to now try and open up all other PSUs that I'm able to open up easily and inspect them for similar cleaning and possible repairs.
     
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  14. CrossBow
    I am only a hobbyist and NOT an electrical engineer. As such I'm sure my terminology and explanations of things will be off or perhaps completely wrong. As such, please let me know in comments on such mistakes as it helps me and all others who might view this video to learn.

    With that, this is my basic intro to my BK 1474 O'scope that I got some time ago and some ways it can be used. This video is only meant for fun and not as instructional as most of my other videos are. Enjoy!



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  15. CrossBow
    Replaced the original 7805 regulators from my atari 5200 recently and installed a pair of DC/DC switching converters in their place. In this video I show the power measurements from the original 7805 and from the DC/DC converters. Next up with be the Intellivision once I get additional parts in.


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