Asteroids Graphic Glitch

For the holiday today I pulled all the IC's and cleaned 'em, hit with DeOxit and re-seated. Still having this graphic glitch. I put my AD board in and it plays fine, so it's definitely the Asteroids board itself.

Been trying stuff I am reading on the net in searches but not having any luck. Still looking for suggestions. :)
 
What is happening in test mode? Are you getting any errors or beep codes?

First thing to do is check your ROMs, particularly the VROM (the single one at the top of the board). I've also seen marginal vector RAM cause glitches. Normally these things are flagged in test mode, but I've also seen cases where the bad RAM is marginal, so it passes self-test, but causes in-game issues. I've seen some cases like this however where if you leave the board running for a few hours, and let it warm up, eventually you'll hear it start reporting beep codes, when the chip fails bad enough to cause a reset, and trip the self-test. These cases are rare, but I've seen them more than once, so I figure I'd mention it.

If it's purely a graphical glitch (and not affecting gameplay, causing resets, etc), and it's not a marginal ROM or RAM, then it's likely something fairly late in the digital chain. It's hard to pin it down to a single chip, but you should focus on the Vector Timer and X and Y Position Counter sections of the schematics.

You can focus on the counter chips in those sections. One trick I use is to check all of the inputs and outputs to make sure they're toggling, but also check the carry signals (that go between counter chips), as I've seen cases where the inputs and outputs will be toggling, but for whatever reason one of the carry signals isn't, which shouldn't normally happen.

Looking at your video again, it almost looks like it could alternately be something in the Z blanking section. This is on the last page of the schematics, and comes together in the LS164 at K9 (or K10, depending on which PCB rev you have). However the BVLD and BLANK signals that come into that chip come from the position counter section, and the State Machine, respectively. One additional thing you can check is the PROM at C8 (or C9). If you haven't cleaned that socket, do so. (It's often socketed, but isn't on some boards). If you have a working AD board, AD uses the same PROM, so you can try swapping them, and seeing if that fixes it. You might want to try this first actually, if they're both socketed.
 
Thanks Andrewb, that's a great help. I'll check out doing that PROM swap today if they both indeed are socketed.
 
Updated. Got to this tonight.

Pulled C8 from asteroids (AD has this soldered to the board so I can't swap test). I had cleaned it before, but did it again anyway. Placed it back in. Went to power on in test mode to hear something as you suggested, and now I am getting solid P1-P2 lights, spot killer light on, no sound. Ugh.

Tempted to swap boards between the two games to rule out power issue but also not wanting to hurt the other machine or board. I resocketed C8 but still got the same result. There is a larger problem occurring I think and I need to start checking voltages from the block & A/R board.

I hope I didn't mess up some fragile connection on the board however.
 
Make sure you didn't put the PROM in backwards. It's easy to do, and I've done it myself, sadly. (If you did, you likely fried the PROM, and it'll be very hot.) Many of them don't have the notched end like most TTL chips, but rather have the dimple/dot, which indicates pin 1.

Also, make sure you didn't bend a pin of the PROM, or fold it under the chip. Sounds like your board is now totally hung.

Do you have a logic probe? If not, it's worth the $20 to get one, as it can give you a lot of insight into what a board is doing. I have an Elenco LP-560, and love it.
 
Oh I have a large photo of the board up on a monitor to make sure I don't put IC's back in wrong, and I double check that. :)

No pins bent, in fact this IC is in pretty good condition.

I guess it was only a matter of time that I would need to get a probe, I'll amazon it and PM you (or if you want to continue this here for others to find it that's fine too).

Amazon suggests this addon: https://www.amazon.com/gp/product/B...g_2?ie=UTF8&psc=1&refRID=PX1DASFSPMSTHGB86DBC

Is it worth it or no?

And thanks for all your help. I'll try to test the voltages before I get this in to rule that out.
 
You don't need those accessories. The probe is self-contained. The only thing I did to mine is replace the heavy, coiled, phone-cord power cable with lightweight flexible silicone wire, which makes it much easier to use, but isn't critical.

You can likely swap boards to help you troubleshoot, but you definitely want to check your voltages first. Always start by verifying power.

Feel free to keep posting here, to keep it documented for others.
 
You don't need those accessories. The probe is self-contained. The only thing I did to mine is replace the heavy, coiled, phone-cord power cable with lightweight flexible silicone wire, which makes it much easier to use, but isn't critical.

You can likely swap boards to help you troubleshoot, but you definitely want to check your voltages first. Always start by verifying power.

Feel free to keep posting here, to keep it documented for others.

Yes, please.

Which logic probe do you recommend?
 
You probably just missed it, but I mentioned my Elenco LP-560 above.

It has the audio feature, which some people poo-poo, but I find very useful. I've found the audio signatures of how different pins are toggling to be a helpful bit of insight, on more than one repair.

They're on Amazon for like $22 shipped.
 
You're right, I did miss that. By chance, I searched Amazon, and because you did say something about "Curley wire", that's the one I wish listed. Thanks for the confirmation on that. :)

Probably going to order that this weekend.
 
Good news, game is working again. Still has this graphic glitch sadly. Test mode is good, no beeps. Probe shows up today.
 
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Well now...

It's fixed. And for nothing I did. I was doing a few minor things today on the cabinet (see my Asteroids link below), and when I turned it on, walla. I guess the board is just very, very finicky.
 

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Well this problem came back again after having the game on for a few hours, and it's worse. The player ship is pretty much a dot on the screen. I just did a recap on the board, sadly that didn't fix it.

I'm going to try and find some of these IC's to replace, so far not having a lot of luck outside of what is on arcadecomponents. Any sites I need to know to get some of these guys?

Thanks.
 
its interesting that just moving things around fixed it for awhile. I had a similar problem with a sega monaco gp problem. I had a board problem in which I had a cracked trace. I would turn the game on and try flexing the board gently and start pressing on chips to see if you can replicate the repair or cause different effects. If this causes changes to the output then you should start doing tap tests around the board to localize where the problem is. watch screen constantly while manipulating the board for any changes
 
its interesting that just moving things around fixed it for awhile. I had a similar problem with a sega monaco gp problem. I had a board problem in which I had a cracked trace. I would turn the game on and try flexing the board gently and start pressing on chips to see if you can replicate the repair or cause different effects. If this causes changes to the output then you should start doing tap tests around the board to localize where the problem is. watch screen constantly while manipulating the board for any changes

Great idea, I was thinking of doing that with the cables on the board connector, it is next in line to get replaced anyway. And I want a Pro Monaco GP, I don' tknow why they didn't carry the headlights in the tunnel feature over to turbo.
 
Having trouble finding a 4016B for this board. This is for M9, N10, etc. The chip in my board is fully labeled as MC14016B.

Digikey has a CD4016BE or MC14016BDG. Which is the correct one?

Edit: This seems to be it.

Also getting TL081 and TL082's. having looked closely at these IC's, one of them has some pretty corroded/browned legs. Could be the culprit.
 
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the first few letters refer to manufacturers and I have a sega super monaco gp for sale
 
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