Maraakate

Great thread. I've always hoped someone would reverse engineer this eventually. If it gets to a point where a server can be properly assembled and ran I'd be OK with trying to setup a VoIP node as a volunteer/donation project. I'm a programmer myself, but only in C-type languages. I can do a bit of ASM, but not a lot. So hats off to everyone here making progress.

Guess it was either cleaning the PCBs or that audio line touching the metal case sometimes. In any case, it's been a couple of days and been using it every day seems fine.

Hi Andrew, Awesome work. If you plan on making the bare boards available with a mouser or digikey parts list I'd be interested in one. Would be nice just for the simple fact that you could have a new PCB that could be upgraded to 1% tolerance resistors in an effort to reduce colour drift during warmup and for long term reliability. The 6-switcher (and probably pre-jr, yes?) PCBs are difficult to desolder and replace components on. Almost as difficult as the vectrex.

Small update. I took some IPA and a tooth brush and cleaned up the boards. While I was at it I noticed the audio line that goes into the power board was touching on the metal case. I don't think this was exactly the problem, but doesn't hurt to fix it. So I've fixed that. So far, so good. The ultimate test will be bringing it over to the GFs house and hooking it up to their LCD and seeing how it holds up on first boot.

Well it appears the problem now instead manifests itself from a cold boot. I've noticed if I leave the machine off and come back to it a couple of hours later then the problem exists for quite some time then magically fixes itself. This morning I powered it up, same problems. So I tried wiggling things around, no change. Took out the heat gun and ran it all over the logic board and switch board. No change, except for the colour drift which is to be expected. A couple of seconds on the mod board and then it popped right into place and was perfect. So I'm not entirely sure it could be the mod board only because the video was wonky on Pin 12. And yes, +5V is good going into that board. However, I'd have to take a peek at the schematic. Maybe something is intermittently ground on that mod board and/or changing amount of draw from being tapped to that mod board? I'll reflow solder on it just to be sure. Only thing I can think of after this is to get a can of freon and spray the boards once the screen is GOOD and see where it immediately gets hay wire after spraying and if that doesn't find it then it's time to bust out the scope.

Well of course, couldn't be that easy! 😄 I got bored of waiting, tried taking a heat gun at progressively hotter settings on the boards and no change. Played the game for quite some time and realized I've been playing it for over 30 minutes. So, put it back together (minus the top) quickly and been playing for another 30 minutes. Got 5664 in Kaboom!, a personal best (normally I peak at 3300-3500). Maybe it's magically fixed itself or the heatgun knocked something into place or a solder blob fell off the board (already checked for solder blobs before...). No idea, but I'll keep playing and keeping an eye on it. If it crops up again I'll start testing around the TIA with the scope and by the 4050.

I suppose you are right. It says on Console5 that it can cause no trigger from joystick or no sync on 6 switch models. Still waiting on the unit to act up (funny it's been acting up this entire time until now!)

Also, sorry I think I missed part of your post earlier with the diagram. Right now, for no real reason, the A26 is cooperating so I have the scope on the 5V going into the mod PCB. So far it is stable, waiting to see if it changes when the screen starts acting up.

By static image, yes I think this is possible with the start screen of Kaboom!. I noticed when the problem isn't happening the output on Pin 12 is stable.

Sorry, what is UAV? Do you mean like "Ultra A/V mod" or something like that? Because, this board is basically a rehash of the old Ben Heck mod with an extra transistor to boost output so it didn't rely on attaching itself to that.

So the 4050 is part of what mixes it? I don't know if I'll be able to swap it for a week unless I happen to find a socket and IC from spare vectrex parts. Might be difficult as I moved a couple of years ago and haven't had to open up a vectrex in a long time *knock on wood*. I'm willing to check different signals off the TIA. They should be stable and not moving up and down (showing wild voltage changes) on a static screen. That to me would indicate the TIA itself is likely fine. What pins are good ones to check in the mean time?

The 4050 is not in a socket. I might, MAYBE, I have a spare from stuff when I worked on my Vectrex units but it's a tossup if I can find it. I thought the 4050 was part of the joystick input or no? Do you know of a way to test if mine is bad without blind replacement?

Yes, I desoldered the entire RF unit. The only initial problem I had with the board (besides it's crud supplied wiring) was that it has you remove a transistor on the logic board. Well, they have you snip it. I desoldered it and found out that this wasn't completing the vias and had to use some wrapping wire to fix this in order to get video again. I suspected that this was not holding up, and I checked that area today after the 7805, etc. replacement but I can try and look harder again. I'm really perplexed, because usually for intermittent solder joint stuff, I have found that flexing the boards usually triggers some kind of change but this does not.

Thanks for the reply, I can check the 5V on the composite mod board, but considering it's happening before that it must be a bad component or dry solder joint somewhere on the logic board. Do you still want me to test that? I know how to use the scope to see waveforms and the like, but diagnosing further gets a bit beyond me at times. I'm guessing what I should be able to do is trace back pin 12 to the next thing and check the waveform before and after those components? I would guess, that at some point in the chain it should be a stable waveform and the component after that would be the bad one or bad solder joint, yes? Where is the actual output on the TIA for video? I could also probe here with the scope and see if it's correct.

Here's a video showing the scope with TV so you can see it's happening from OUT of Pin 12 on the logic board. This eliminates the possibility that it has anything to do with my TV, RCA cables, or the switch board:

As I wait, I traced back the video output from the switch board to pin 12 on the ribbon cable that runs to the logic board. I hooked a scope up to pin 12 on the logic board side and the noise/video garbage happens the same on waveform as on the TV. So I think we can rule out the mod PCB or the switch PCB.

I already replaced the 7805/Voltage Regulator and it's offending "chiclet" cap. I initially suspected that was part of the problem, or if it wasn't that it would be soon enough anyways since it's apparently a common issue.

Also 12V should be OK with a modern 7805 (which I am using) for some short tests like this. It may make it run a bit hotter, but I believe they are rated up to 24V or so.

If you really want me to, I can go grab my bench supply set it to 9V. But I really do not think it is the power supply and rather an intermittent component. The problem begins after the console has been powered on for a bit, then requires a long time of cool off (maybe up to an hour? haven't timed it) before it's stable again.

Just tried it, not the power supply.

OK, I'll just grab a 12V 1A and splice the ends re-use the 3.5 jack and report back,

The one I have is original, but really? They can be bad enough to let the system show things on the screen and play a game but cause the problem I'm happening? I would think if it's junk then it would just be rapidly restarting the system or something?

No, how would I go about doing that? By power supply you mean the actual "wall wart" and not the 7805, yes? I would like to think it probably works if the game is playing but the screen is intermittent. I can start the game and hear sounds, just the video keeps flickering. That's why I'd like to know how do I trace with the scope the video coming out of the TIA to see if it's correct and that it's not some bunk component on the mod PCB. Here's a video showing what's going on. Ignore the cat in the background 😄 https://www.youtube.com/watch?v=MdwVVOEesRA P.S. The video makes it look a bit brighter than it actually is.

Hey everyone, I have a "new-to-me" Sears Telegames/A26 Light-Sixer Rev. B PCB console. Initially, I tested it on one of my CRTs with an RF adapter. Was pretty noisy/fuzzy but worked. One thing I did notice (not sure if this is related) that one of the channels was better to use than the other. Since I want to hook this up to the LCD for the kids to play Kaboom! on I ordered a composite mod board from VintageGamingAndMore, specifically this one: https://vintagegamingandmore.com/product/atari-video-mod-kit-2-0/. The mod was kind of a pain because of the supplied wiring, but I used my own wiring and got it working. Everything was working great until after playing it for about 20-30 minutes the display started getting darker and started flickering as if losing sync. I suspected the video cable, TV, or soldering from the mod. I checked all this out by replacing the video cable, trying other inputs on my TV, and reflowing solder and wiggling the wires on the mod PCB with a pair of chop sticks. Problem still persisted. What I did next was get the capacitor kit from Console5 and replaced the 7805 VR, the two electrolytics, and the "chiclet" cap on the switch board. On the logic PCB I replaced the electrolytic and the two polystyrene caps (not really necessary, audio works fine, but while I'm in there...). I suspect a component that drifts in tolerance once it's good and warmed up, which I may have to track down with freeze spray/computer duster (which is kind of hard to find in my area these days :/) or possibly the TIA. I'd rather not blindly replace stuff if I don't have to. Has anyone had this problem before and how did they resolve or diagnose it? The TIA's are expensive and I don't want to just throw money at it if that's not the problem. I do have a scope and other tools if probing problem areas to test would be useful. EDIT: Forgot to add I already tried flexing the boards lightly to see if it was an intermittent solder joint/via but it doesn't appear to be the case.

About 10-15 years ago I had an A26 Jr that I modded with instructions online to output composite. Then that A26 got lost in a move and I just acquired another one. The difference with this particular mod was that it had two pots for adjusting the colour tint and I believe saturation. It was a pretty easy mod to do. I can't seem to find instructions on it any more. The newer mods seem to be based around a 2N3904 with 2 bias resistors and seems to be hit or miss. Does anyone know which mod I'm referring to and where the instructions can be found for it? Thanks!