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7800 oddity - a Maria that kinda? Works?


CrossBow

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Had a 7800 come into the ITC lab to get refurbished, and upgraded with a few things. Among the updates was to get a UAV plus mount board setup as I've been doing for over a year now.

This is where it is important that you always...ALWAYS test the current status of electronics before you dive in and start doing stuff. A rule I didn't follow so what I discovered after putting all this work in, isn't something I could verify was an issue before the work started. I had been told that it was working 100% without issue as it was the daily driver 7800 for the owner. 

So what was the issue I discovered? Well, after installing the UAV setup and the 10pin mini din AV connector to test the system. I saw something odd when I ran Ballblazer for burn in testing. What I saw was odd additional background graphic information on the far left and far right sides of the screen that I'd never seen before? More specific...this is what Ballblazer looked like:

78_BB_extra_graphics.jpg.2af468b1df21a160c62c591a4fe4c174.jpg

So if you look on the left and right hand side of the image, you will see what looks like the blue in the sky being extended out along with some burgundy like brown/red below that. Now oddly enough the 5200 version of the game through a UAV actually looks kinda like this, but on the 7800 this isn't normal. Here is a closeup detail of the effect and you can see it is more like a checkerboard pattern within those extra graphics being shown.

78_BB_extra_graphics_detail.jpg.be4dfc8e20ef428b44606ec57ae1d1b7.jpg

Making matters more confusing was that NOT everything had this effect going on. Ballblazer seemed to show it the worst but any game using a colored backgrounds would have this kind of effect going on. But anything using a black ground was fine as this color hue test screen shows from the 7800 utility program:

78_colorbars_unaffected.jpg.1336fdd5aa1f584181288b18912d6c38.jpg

I did figure out pretty quickly that the issue had to be something with the Maria IC because this same effect wasn't happening on 2600 games and was only present on 7800 titles. So a few days of delay (Waiting on a new heater for my desoldering gun), I removed the original Maria IC, installed a pair of new 24pin sockets (As I don't have 48pin on hand). And installed a different Maria pulled from a parts donor 7800. And what did ball blazer look like after that?

78_BB_Fixed_Maria.jpg.3149db1f9ea629edbd5d18c88c7663da.jpg

It worked! So yes after nearly 150 Atari 7800s that I've worked on, this was a first. My guess is that this 7800 always had this issue but as it was mainly used on a CRT and was only present on 7800 games, it likely wasn't noticed or the owner simply thought it was normal. In any event the original Maria was working in that the actual game play area on the screen looked normal otherwise. But the blanking to mask the extra graphics junk on the sides, wasn't working properly on this Maria and only by swapping it out with another was the issue fully resolved.

 

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hi crossbow,

 

 nice work. agreed on the electronics. i always demanded the power supply, t.v. switch box, and controllers to boot, if a customer wanted service. many times it turned out to be a power supply problem.

 

lance

www.atarisales.com

 

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38 minutes ago, Video 61 said:

hi crossbow,

 

 nice work. agreed on the electronics. i always demanded the power supply, t.v. switch box, and controllers to boot, if a customer wanted service. many times it turned out to be a power supply problem.

 

lance

www.atarisales.com

 

I only request the consoles to be sent in because I have spare PSUs and controllers, plus several different test carts for servicing the consoles. There has only been a few times where something arrived working 100% for me that didn't work for my clients and yes...it was indeed their power supply that was faulty in those instances, or in one case, the video cable the owner was using apparently had some loose connections in side it.

But I normally pre-test all consoles to verify the issues that are being reported or to find issues that the owner may not be aware of. An example of this would be a faulty player 2 difficulty switch or the paddle controllers not working properly for player 3 or player 4 on a 2600/7800 console. Because they might not normally use those functions, they aren't aware that they were faulty.

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10 minutes ago, RickR said:

Fascinating.  I wonder what kind of problem in the chip would cause it to "almost" work like that? 

Nice work fixing it!

 

There is a dedicated blanking pin on the Maria. However, the odd bit is that the pin is only attached to the expansion port bus and doesn't seem to go into anything else within the video circuit. But obviously that isn't the case or there are additional signals being provided by the Maria that effected this that weren't working.

It wouldn't have surprised me if this was always an issue with this 7800 that again, just wasn't really discovered. When playing on a consumer level CRT, that extra info was likely in the overscan and just wasn't noticed.

 

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6 hours ago, CrossBow said:

I only request the consoles to be sent in because I have spare PSUs and controllers, plus several different test carts for servicing the consoles. There has only been a few times where something arrived working 100% for me that didn't work for my clients and yes...it was indeed their power supply that was faulty in those instances, or in one case, the video cable the owner was using apparently had some loose connections in side it.

But I normally pre-test all consoles to verify the issues that are being reported or to find issues that the owner may not be aware of. An example of this would be a faulty player 2 difficulty switch or the paddle controllers not working properly for player 3 or player 4 on a 2600/7800 console. Because they might not normally use those functions, they aren't aware that they were faulty.

hi crossbow,

i learned very early on, that sending back a fixed unit, and then the customer plugs in a faulty power supply, controller, etc.,can avoid many headaches.

i to used my own test equipment. but i always wanted to make sure that all parts of a system, were solid.

lance

www.atarisales.com

 

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@CrossBow it's really too bad that most other companies/technicians now days do not perform their jobs with as much diligence and integrity as you.  You sir, are the only person I will recommend in the future if I meet anyone that needs or wants an upgrade or repair on their classic Atari units.  You always seem go above and beyond and exceed expectations.  I know my 5200 experience with you was awesome. 

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12 hours ago, Video 61 said:

hi crossbow,

i learned very early on, that sending back a fixed unit, and then the customer plugs in a faulty power supply, controller, etc.,can avoid many headaches.

i to used my own test equipment. but i always wanted to make sure that all parts of a system, were solid.

lance

www.atarisales.com

 

Lance,

The reason I don't ask for all of their stuff is because it simply increases the shipping cost too much. Power supplies add quite a bit of weight in many cases and with shipping being what it is today, each pound adds up. I get what you are saying, but in most cases, I've done some troubleshooting with my clients ahead of time to make sure something simply like a bad PSU or controller isn't to blame first. Here is a such an example that happened last night in fact:

Had someone reach out to me through my FB profile for my ITC services. It was recommended they reach out to me to look at having their LCD replaced in their Lynx console so they wanted to know how much that would cost etc. With some questions, I asked why they wanted a new screen. And they stated because their original wasn't showing anything head on and you could only just make out the image when viewed from an extreme angle so they were looking to one of the newer screens installed etc. 

I asked them if anything changed when using the contrast wheel on the system... and they came back about 30min later stating they completely forgot that wheel was there and it was looking like it did originally again and thanked me for my time. I was happy to do that and while I could have insisted they get a new LCD still, it was only being suggested because they thought their screen wasn't working. It was and now they can play it as they wish. 

I would like to think that actions like that, will have them remember me when they might be in actual need of my services in the future so again, I try and make sure the simple stuff has been tried first for my clients before they send it all my way.

 

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On 3/26/2024 at 8:47 AM, CrossBow said:

Lance,

The reason I don't ask for all of their stuff is because it simply increases the shipping cost too much. Power supplies add quite a bit of weight in many cases and with shipping being what it is today, each pound adds up. I get what you are saying, but in most cases, I've done some troubleshooting with my clients ahead of time to make sure something simply like a bad PSU or controller isn't to blame first. Here is a such an example that happened last night in fact:

Had someone reach out to me through my FB profile for my ITC services. It was recommended they reach out to me to look at having their LCD replaced in their Lynx console so they wanted to know how much that would cost etc. With some questions, I asked why they wanted a new screen. And they stated because their original wasn't showing anything head on and you could only just make out the image when viewed from an extreme angle so they were looking to one of the newer screens installed etc. 

I asked them if anything changed when using the contrast wheel on the system... and they came back about 30min later stating they completely forgot that wheel was there and it was looking like it did originally again and thanked me for my time. I was happy to do that and while I could have insisted they get a new LCD still, it was only being suggested because they thought their screen wasn't working. It was and now they can play it as they wish. 

I would like to think that actions like that, will have them remember me when they might be in actual need of my services in the future so again, I try and make sure the simple stuff has been tried first for my clients before they send it all my way.

 

hi crossbow,

 

 understood on the shipping, its getting intolerable. you are providing a fine service. with old guys like me can no longer service atari, someone has to step in.

 

lance

www.atarisales.com

 

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