(Solved) Atari Battlezone - Vector Generator Woes

Ok. When you booted into test with just the main board, was the CPU watchdogging?
No watchdogging without the auxboard connected. Unfortunately I don't have the luxury of a working additional battlezone set, so I'm on my own on this one. I belive I have the DACs in stock, so I can take a closer look at that tomorrow.
 
Ok. In that case we can focus on the video section.

I would normally check all inputs to all of the DACs with a logic probe, to make sure they are all toggling. If you have experience with these (again, which you can get from another working board, or just experience), you can get to recognize what 'normal' toggling sounds like, with an audio logic probe. (Or rather it's easier to hear when it ISN'T right.) But you should basically get fast toggling on all inputs of both DACs. Just another quick and easy check you can do to gain higher confidence that the VG output is good.

Another trick with the video section is that you can divide and conquer that as well. You can use your scope to probe at the XOUT/YOUT test points (as you're doing). But you can also probe at the first TL082 outputs after the DACs. You can't probe the DAC outputs directly because they are current signals, not voltage. So the first place you have access to what's coming out of the DACs is both pin 7's of A10 and D10. And ideally you should get a full image, though scaled down a bit.

You want to see if you can get an image there first, as there may be other issues further downstream in the video section. And if you only probe the XOUT/YOUT test points, you're seeing the combination of what could be multiple video issues.
 
I would normally check all inputs to all of the DACs with a logic probe, to make sure they are all toggling. If you have experience with these (again, which you can get from another working board, or just experience), you can get to recognize what 'normal' toggling sounds like, with an audio logic probe. (Or rather it's easier to hear when it ISN'T right.) But you should basically get fast toggling on all inputs of both DACs. Just another quick and easy check you can do to gain higher confidence that the VG output is good.
Saw quick toggling on both x and y. Looked pretty clean too. Replaced the X DAC and we got a cross hatch pattern now.

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With the aux board connected, I sometimes have a picture sometimes nothing.
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It also looks like it is reporting a bad chip. Almost looks like J1 or maybe H. Can't really tell. (Also with the aux board attached)
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Bang. Nailed it.

You could hook to a monitor now, and read that error code on the left (which I can't tell, but should be an aux board error.)

And then try self-test with the aux connected, and see if it gives you any more error code clues.

You said you were getting uncontrolled shooting and other sounds. That suggests Pokey. If you have any known-good spare Pokeys on hand, you might want to dig them out, for trying on the aux.
 
Bang. Nailed it.

You could hook to a monitor now, and read that error code on the left (which I can't tell, but should be an aux board error.)

And then try self-test with the aux connected, and see if it gives you any more error code clues.

You said you were getting uncontrolled shooting and other sounds. That suggests Pokey. If you have any known-good spare Pokeys on hand, you might want to dig them out, for trying on the aux.
I updated my post to add more detail. Looks like you were a bit quicker than I. I do have some Pokeys, so I'll throw it in.
 
I think we are on the right track here. I reseating the bitslice processors and got what I think was an 'L'. Anyway I have one new bitslice so I did process of elimination since I didn't know what it meant off the top of my head. Ended up being a bad H/J2. I am as far as I can go for now! I am still doing all the harness shinanigins. I got deflection but no picture. So either the Z input is goofed or I need to fart around with the monitor. That is tomorrow's problem though.
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I may be running a bit late to work this morning because I wanted to do a bit of troubleshooting. Turns out, my z output was dead on the game board. Probing back, I see that the input to Q7 looked good but nothing on the other side. I didn't think that a 2n3906 would be the problem, so I checked Q8 which can pull that output low. The base was always high, which means the z output couldn't be active. That went back to the NOR gate at N9. Who's inputs were both low. Explaining the high output. Getting to the 74ls164 shift register at P9 though, it was getting a clock and valid inputs. No shifting though. I replaced the 164 and that brought back my Z. Which made my monitor light up as it should! Needs a bit of adjustment (and the gels reattached), but realistically it can be played!
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Considering this topic closed for now. I can troubleshoot sounds when I get there (I need to make a control panel harness first). If it dies (as some vectors do shortly after bringing up) or I run into sound issues I can't figure out, I'll post about it. Thanks everyone for your insight. It was insanely helpful.

  • The damage from this repair:
  • One AM6012 DAC
  • Two 2114 SRAM
  • One 2901 bitslice
  • One 6502 CPU
  • Entire ROM set worth of 2716s
  • One POKEY (tbd, need to do more testing on that one)
  • One 74LS164
 
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That 164 is another common failure. I'm willing to bet it was a Signetics brand chip.

Glad you're up and running.
Yep, Signetics. Did they just make bad TTL chips or just specifically 164s? I've not had a ton of issues with signetics chips in the past, not like with Fujitsu chips for example.
 
They made bad chips. Not just 164's, but any Signetics chips on these boards should be suspect. If you're troubleshooting and see one in an area you're suspecting a problem is in, you have a pretty good bet replacing the Signetics chips in that area. (And even if you're wrong, you're still improving the board by replacing a weak point, since they statistically do fail more often.)

It also isn't just the chips, but the combination of a Signetics chip in certain locations will increase the probabilities even more. That particular 164 in the Z section is one of them, and I would have mentioned it if we'd confirmed you had no Z. But it's to the point where I've seen the same bad Signetics chips in the same locations so many times, I look out for them and will replace them proactively.

Another one to check on your board are the LM319's in the video section. If those are Signetics, do yourself a favor and replace them now, before they go bad. Those are another very high probability failure.
 
Another one to check on your board are the LM319's in the video section. If those are Signetics, do yourself a favor and replace them now, before they go bad. Those are another very high probability failure.
Noted, I don't think I actually stock those so I'll order them with my next digikey order. Not sure though, not looking at the parts closet right now. Love getting this kind of insight, I like repairing this stuff but don't quite have the experience yet.

The 2114s were some brand called "Semi", can't say I've heard of them before.
 
Yeah, the LM319's are obsolete, and getting harder to find from major suppliers. I checked my notes, and the last tube I bought I got from Mouser, but those are sold out now (P/N 512-LM319N). However they're showing these TI's in stock at the moment (barely):


Turns out Digikey has them as well (though only 412 left). But these are the only through-hole ones either site has.



The 2114s were some brand called "Semi", can't say I've heard of them before.

Probably because their stuff was only Semi-working.
 
Yeah, the LM319's are obsolete
Texas instruments shows them as active on their site. Digikey says the same too. Not a whole lotta folk making TTL chips in general outside of texas instruments. Always worries me when I see EOL emails from digikey.

Also, there is plenty of stock of LM319 on mouser, just they switched to the lead free versions. About 1100.
926-LM319N/NOPB on mouser.
 
The Onsemi ones I bought last time are obsolete.



I'm not worried about not being able to get them. There are always other sources. It's just convenient when you can add them to a Digikey order. The reason I got them from Mouser last time was because Digikey didn't have any, as I mainly only use Digikey. Except when they don't have something and Mouser does. And/or if Mouser is significantly cheaper, as I buy big lots. (When I buy a chip, I don't want to buy it again for a long time.) It's always good to compare, as you can save $10-20 on a lot sometimes, between vendors. Multiply that by several lots, and it adds up.

These chips will always exist on the NOS/salvage market, as well as the gray market from China, when they do eventually disappear from major sources. It's just interesting when parts are in this category of 'barely still supported', where the major suppliers will stock them, but only one part number at a time.

There are plenty of SMT ones on both sites, too. This is just the through-hole ones.
 
I'm the same way. I got a whole closet in the office full of parts shelving. When I order parts like that, I order ten extra typically. I just can't remember if I stock them. I wonder if my inability to remember things this morning like this has to do with staying up too late fixing a battlezone and getting up early for work anyway...
 
Yep, Signetics. Did they just make bad TTL chips or just specifically 164s? I've not had a ton of issues with signetics chips in the past, not like with Fujitsu chips for example.
Is it labeled "SA"?

 
Is it labeled "SA"?

No, just S.
 
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