drewscruis
Well-known member
Funny my asteroids had a hum and it was the connector for the monitor. Noticed when I wiggled it it would go away. Repinned the connector and fixed my prob.
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Loud hum is almost always a bad TDA2002 on the AR, especially if it hums without the game board plugged in. You can use a DMM set to AC mV to test the SPKR1 and 2 test points on the AR, with no game board plugged in, to see which TDA is generating the hum (though you probably should just replace both, if you're going to do one of them.)
For the sparking fuse, is the fuse the correct value? Sparking usually doesn't happen on the deflection board, but those two top fuses will just straight blow if one of the deflection amps on the board is bad, or the frame transistors are bad. My guess is you're getting a large inrush current, but the fuse is glowing, but not blowing(?) The fuses should be 2A fast (i.e., normal) blow, not slow-blow.
Test the 4 heatsinked transistors on the deflection board first (using a DMM), then all other small black transistors. You can check them in-circuit for most cases, though it is possible to have them go bad in ways that you can't see unless you remove them, but that's maybe 5% of the time. It helps if you have a known-working good board to compare to, but in your case maybe you can use the other bad board as at least a partial comparison.
Also test and/or just replace D608 and D708, as these frequently go bad, esp if they are the original glass ones. They are fairly close to the large hot power resistors, and take a lot of heat.
Also, test your frame transistors. (There is a technique for doing this quickly in my 6100 set-up guide, which you can use identically for b/w vector monitors.)
Also, do the mod where you bypass R100 and R101 with straight wires (see the FAQ), and replace Q500, 501, and 502, as these frequently cause issues, from being cooked next to R100.
FWIW, I've found that hum is either:
1. bad LM324 amp on game board; missing caps/resistors also perhaps around this IC
2. bad grounds or connections (edge etc)
3. bad TDA2002 amp(s) on ARI
Fixed many an asteroids by replacing #1.![]()
Funny my asteroids had a hum and it was the connector for the monitor. Noticed when I wiggled it it would go away. Repinned the connector and fixed my prob.
So made some progress on the picture issue tonight, but still have issues. I did a cap kit, re-soldered all the edge connectors, and changed the four bottle caps.
I now got rid of the collapsed screen and have a full screen. However, I still can not get rid of the extra lines, and bright center dot.
Once again brightness pot on the deflection works, but the contrast does nothing. Would the contrast pot be the one to remove the extra lines and bright dot if it worked?
Is this the LL PCB I fixed for you? If so, I doubt it's the logic PCB.Video, sound and game play worked in my LL cabinet.
You always have the option of sending it back ...... I'll do a warrantee repair ... even though you never had to pay me to fix it in the first place. LOL


For some background, there are two versions of the 801 described in the 801 manual, a '25V version' (which operates on 56V, or a 28-0-28 transformer in the brick), and a '35V version', (which operates on 74V AC, from a 37-0-37 transformer). The 35V version is also labeled as a 'G05-802', but this is not the same as a true 802, as described in the 802 manual (and nobody seems to know why Atari did this, so it's just one of those mysteries). You need to look at the zener diodes on the monitor's power board to see which version you have. (Details under link below).
The 802 is listed in its manual as 30V (which is actually 60VAC, from a 30-0-30 transformer in the brick). So, depending on how accurate your brick is, AND which version of the 801 you have, you may or may not be able to get away with driving an 801 from an 802 brick (but chances are you'll be overdriving it, as I *think* most 801's are the 56V type, though I have limited data to support that, so take it with a grain of salt).
I don't have much experience with trying lots of combinations, as I just always make sure to use the right brick for the monitor, and measure brick to confirm. The bricks and harnesses are pinned differently, to prevent you from plugging the wrong stuff together, but some people have tried to bypass/repin/etc to get around that, so you should always be suspicious of what you have, check the pinout against the schematics, and measure the voltage with a DMM.
If you want a related thread, see here. But the info all comes from the respective manuals:
https://forums.arcade-museum.com/showthread.php?t=329297