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RF Interference on Composite modded 2600? Homebrews only


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#41 Atarileaf

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Posted 21 June 2018 - 03:00 PM

What is a good modern source for replacing the metal tape and if I can't find a replacement shield can I at least ground the tape to the metal on the board that the shield attaches to?



#42 CrossBow

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Posted 25 June 2018 - 03:59 PM

You don't need the same exactly stuff as before. All you really need is a decent size piece of wire to solder the outer casing of each switch and then eventually solder that down to the RF ground plain somewhere. But if you really want to use foil tape like before, then you can just buy a small roll of Chrome repair tape from an autoparts store and cut it as needed. It is basically the same stuff.


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#43 Atarileaf

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Posted 01 September 2018 - 03:23 PM

Well after several months I finally got around to installing a new mod from ebay. I took the original apart and started from scratch. Unfortunately the problems still persist so it's not the mod itself after all. I'll attach pictures but if you go to the first post you can see the output is the same. Lady bug in particular looks horrible but I had that problem from the beginning even on unmodded systems through RF. It's hard to tell on the Draconian picture but there are wavy lines all through the picture. So should I take an RF shield from another Vader and put it in this one? The original was thrown out by the person I bought the modded system from. Or is there another possible reason for this RF looking interference on a composite modded system.

 

Again this only seems to happen with 3 homebrews - Draconian, LadyBug and Fall Down. 

 

Space Rocks, Juno First, and Colony 7 seem fine and all original games look great too. So other than 3 games this mod seems to work fine. It seems to be a homebrew issue but Al mentioned he's never seen anything like it and considering how many hundreds of homebrews and systems he tests, I trust it's something peculiar to my Vader.

 

PS - This was my first attempt at modding a system myself so other than the original problem being present, I'm pretty proud of myself icon_mrgreen.gif

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#44 RickR

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Posted 03 September 2018 - 10:17 PM

You did a nice job!  I'm sorry that the bug is still there.

 

It still feels like a potential power issue to me.  Good luck solving this. 


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#45 CrossBow

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Posted 05 September 2018 - 01:37 PM

I hadn't thought of power...but could be. The original VRs are only like what.. 500ma rated? And that could have been pushing it already to near that limit with all the components installed. Wonder if a newer and higher output 1amp version 7805 would help?

 

Especially when the newer homebrew games also take up some juice to power the additional chips in them that they have. 


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#46 Atarileaf

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Posted 05 September 2018 - 04:09 PM

It's a possibility. The AA user who did the original mod did say he replaced the voltage regulator but I don't think he mentioned if it was 500ma or 1amp. I may have some extra's from Console5. I believe these were the ones I bought, I believe they're 1amp https://console5.com...-regulator.html

 

PS - I didn't take a pic but I used strips of that metallic tape and bridged the switches on each side and then from the innermost one to the metal strip that runs along where the rf shield would normally sit. I hope that is sufficient to preventing and static issues. So far so good though.


Edited by Atarileaf, 05 September 2018 - 04:15 PM.


#47 CrossBow

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Posted 06 September 2018 - 11:32 AM

Yes the metal strips where you placed them should be fine. I still would have tried to solder on some wire instead to make sure it was all grounded properly. I still think part of the issue is that you don't have actual RF shielding on the system anymore. I see this kind of thing even on modded consoles like my Colecovision, Intellivision, and especially the 7800 if I don't find ways to put the RF shielding back on. 

 

And yes I believe console5 only has 1amp and up output VRs that he sells. I bought my 2amp output versions from him last time I believe and that is what I have running in my sega Genesis.


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#48 CrossBow

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Posted 06 September 2018 - 11:39 AM

Also you can literally grab your ground for these AV mods from anywhere. Take any multimeter and you will see that all grounds have continuity with each other in these old systems. So..to make it easier I will usually just find the nearest ground point around the circuit I'm grabbing my signals from to be sure it is proper. In the case of the 7800 UAV mod I use the grounds off the UAV board itself. But honestly you could just grab the ground off of any part of the large ground plane around the main board and attach that to to your RCA connections and be fine.


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#49 Atarileaf

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Posted 08 September 2018 - 05:59 PM

Well if I come across any 4 switch parts machines in the future I'll just grab the rf shield out of one of those. Wouldn't I have to cut a slot out of the shield since I'm running one wire soldered to the base of a resistor that sits inside the shield area?



#50 CrossBow

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Posted 08 September 2018 - 06:59 PM

Yes, you would still need to cut a small notch out of the RF shielding for the audio input wire you have there. (I assume the yellow is audio input since it is tied to two resistors, one for each TIA channel?)

 

Unless there is just enough space to wedge that wire between the audio tuning coil? But you would have to desolder it from the resistors, thread the wire through the RF opening for that coil to come through and then solder it back down. Things like that are why I solder on header connectors to most of the wiring so I can easily take it loose for full disassembly without have to desolder stuff.


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