Yet another asteroids that plays blind!

microshaft

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So, first post. I picked up an asteroids cabinet free off craigslist almost 10 years ago that according to the giver had "recently stopped working" and have finally gotten around to trying to see if I can't get it working.

Spot-killer is on but otherwise it seems to play fine. I've gone over some of the obvious stuff, refluxing and recapping the deflection board and HV supply didn't fix it. I have a set of chasis transistors and a few diode bridges on the way. (The transistors aren't shorted, but they were cheap enough.) The only odd bit is that R100 is *toasty* and R101 is cool.

I think the X/Y/Z voltages from the game board are far too low but... the game board is.... just weird in a distinctly hand made way. What am I looking at here?
 

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Looks like a non-Atari PCB. Maybe a copy, as the design looks essentially the same, but that's not an Atari-made PCB. That's likely more of a footnote though, as the board may function the same (but maybe not, though I'd suspect so).

First, check the DC and AC levels on the XOUT and YOUT test points/pins of the game board. You should have between 0 and 1 volt for DC, and 2-3V AC, though it may fluctuate as the attract mode cycles.

For the deflection board, you probably have broken solder joints on R100 or R101. They can be hard to see unless you wiggle the resistors while looking at the joints. When one breaks, all of the current gets forced through the other resistor, roasting it (though the monitor may still work). You see a lot of these deflection boards with a brown spot under one of the resistors, due to this issue, as it's fairly common.

Regardless, you should do the standard mod of removing those resistors, and replacing them with a pieces of wire. (They were removed from later revisions of the board, so it's safe to do.) Also, replace Q500, 501, and 502, as they often get toasted from the hot resistors. Here's a thread about it:

https://forums.arcade-museum.com/showthread.php?t=403888
 
Maybe also try replacing the 2N3055 transistor on the sound board. I had a similar issue and that fixed it.
 
Maybe also try replacing the 2N3055 transistor on the sound board. I had a similar issue and that fixed it.



If it's playing blind, that means the 5V is ok, which means the 3055 is ok (as it's one of the main parts of the 5V regulator circuit on the AR board).

If it *wasn't* playing blind, and the 5V was low, then the 3055 would be the first thing to replace.
 
Simple stuff before attempting to repair the monitor or the pcb. Sounds like you have some skills. Excuse me if you already know this...

Playing blind as in you can play the game just not see the game on the screen or does the player one and two just blink at you qnd nothing happens when you coin up or press the player one or two buttons.


Do you have neck glow on the crt?
No neck glow mean the asteroids will play blind.
Check the fuses on the brick power supply. Check the harness for crossion on the pins.
Check the harness that connects to the crt make sure the pins are tight.

Do you hear the crt make chattering noises? Vector monitors with make noises not like a raster montior.
Do you feel the static on the crt tube face. Dont be grabbing the red high voltage wire.. a nasty high voltage shock might get you..

Hope this his helps.
 
Plays blind as in, makes convincing pew pew, engine and other sounds but nothing on the screen.

Neck glows bright for a second or so if it has off for a bit, dim otherwise, and then dim as the spot killer kicks in.

I've checked the PSU, fuses, inspected harness and connectors, some of the deflector board plugs seemed cracked so they got refluxed.

I'm not sure if the CRT make the chattering noise, I've heard it referred to a few times and I haven't checked for static on the crt face since I've been working on it in the cabinet.

I'll keep plugging along. No real skills here, but I'm handy with my soldering iron and pump and know just enough about these things that I have a reasonable chance of at least not making it more broken. And know to keep away from the HV end of things unless it's been discharged. Twice even. :0

It had never occurred to me that these old games were so valuable that they were bootlegged and cloned when they were new.
 
Measure the AC and DC levels on the XOUT and YOUT test points of the game board (per my post above), as that will tell you immediately if it's a game board issue or not. There's no point in mucking with the monitor if the game board isn't putting out good signals.

Post the values here, and I can tell you if they look ok.
 
Measure the AC and DC levels on the XOUT and YOUT test points of the game board (per my post above), as that will tell you immediately if it's a game board issue or not.

Y out is reading ~3v AC and ~1v DC.
X out is reading 0v AC and -12v DC.

Any tips as to why X out would be stuck and -12v DC?
 
Y looks ok (DC is a little high, but it could just be the adjustment).

X is hosed. You have at least 1 bad chip in your analog video section, maybe more. When this happens, the outputs can get stuck and up to + or - 15V, which is what many of the analog chips run off of. You do not want to hook that board up to a monitor in that condition.

Unless you have a scope, and the means to desolder and replace chips cleanly, you probably want to send it to someone, as trying to fix it yourself could just damage the board. Atari PCB's aren't very forgiving soldering-wise, and a bootleg board is probably worse.
 
My DMM has a scope function and there's a vacuum desoldering station that's been floating around work that I could borrow. The traces on this board do pull up very easily, I already figured that out when replacing a dodgy looking mylar cap.

I guess I'll poke around and see if I can trace it back to a stuck output pin somewhere. Maybe I'll get lucky otherwise I think I'll probably be in the market for a working Asteroids board to pop in this cabinet. Gives me an excuse to buy a logic probe anyway.

Thanks for the help!
 
I suspect a digital DMM scope might not be enough, as you usually want an analog one for vector stuff, especially if you haven't worked on one of these before and aren't familiar with what the waveforms should look like at the various points after the DAC (where it's all analog). Looking for stuck pins won't help you really, because it's all analog switches and amplifiers after the DAC, one or more of which is bad.

You can try replacing the final TL082 for the bad channel first, and then working your way back, as those frequently go. One trick you can also try is using the back of your finger to check how hot each of the analog chips are in the X chain. If any are scorching hot to the touch, they are bad. Google the Asteroids schematics to see which chips are which, as your board is likely the same basic design, and maybe even layout.

Note also the DAC itself could be bad, which you'd need to swap out to really tell for sure. Also, for any chips that you do replace, you want to install a dual-wipe socket (not machine pin) for the replacement, as the analog chips tend to fail more than the others on the board, and if they ever go bad again, you won't need to desolder them, and risk pulling traces (as the traces can only tolerate so many soldering/desoldering cycles).

Also, when you do install the sockets, use as little solder as possible, as it's very easy for too much to spill over, and cause shorts underneath the socket. (Test all pins for shorts with a DMM before inserting the chip and applying power.)
 
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