Asteroids Arcade game vector issues? - Page 1
Forum section: electronics / repair

author: RobII
author_rank: Regular Contributor
timestamp: November 07, 2015, 06:53:30 pm
content: Hi electronic Guru's!! I have a sick Asteroids arcade game. Currently the game plays blind (Game plays but no graphics on the screen). Before I start tearing into the monitor chassis I want to make sure the PCB is outputting the proper signals.I have verified the 5vdc to the logic and 36vac to the vector section.I hooked up a scope and tried to get some good pictures but I'm not sure they will be of any useHere are the X and Y outputs, I think the Y output is on the bottom.I also uploaded a short videohttps://youtu.be/xghOtT-se40I am not an electronics engineer but can navigate my way around a PCB. Any suggestions on where to start would be most appreciated!!

author: miguelvp
author_rank: Super Contributor
timestamp: November 07, 2015, 07:00:15 pm
content: Put the Scope on X-Y mode, you should be able to actually see the graphics because that's pretty much vector mode.

author: RobII
author_rank: Regular Contributor
timestamp: November 07, 2015, 07:02:55 pm
content: Did that. The last few seconds of the video are what I get in X-Y mode.Quote from: miguelvp on November 07, 2015, 07:00:15 pm

author: Macbeth
author_rank: Super Contributor
timestamp: November 07, 2015, 07:05:38 pm
content: You should see something like the real thing in X-Y mode, though the blanking intervals are probably showing up and making a mess. Does it use the Z for beam intensity?You say the Atari CRT has no output at all? Have you checked its getting EHT?

author: wreeve
author_rank: Unknown
timestamp: November 07, 2015, 07:13:15 pm
content: is the spot save circuit kicking it? I think there is a red led which indicates it's on. It's there to stop the phosphor burn in when the beam isn't moving.

author: RobII
author_rank: Regular Contributor
timestamp: November 07, 2015, 09:09:37 pm
content: It does use Z for blanking retrace lines but I'm not getting any recognizable game output in XY mode.The spot killer LED is on, on the monitor deflection board but that could also mean it's not getting a proper signal from the PCB. If I turn up the brightness I do see a dot in the center.Since I'm not getting any kind of game output on the scope, I am leaning towards an issue with the game PCB.Quote from: Macbeth on November 07, 2015, 07:05:38 pm

author: Macbeth
author_rank: Super Contributor
timestamp: November 07, 2015, 09:28:48 pm
content: 0.2v per div - I'm guessing 2V per div with x10 probes, that still isn't enough to drive the deflection plates. But there is clearly some "intelligence" in the X/Y signals that would indicate a game field that is working. So the output amplifiers have failed. But it would be exceptional for both amplifiers to fail at the same time (to give a single dot).Now I have to admit my work used to involve raster scan TV stuff and so a field collapse would be one fault or a line output fault was much more common (and would take everything else down with it as the LOPT generated all the other supplies including field). I'm guessing with a vector screen the X,Y are supplied by the same voltage - so rather than the amplifiers it would be the supply for them that has failed. Something in the low 100's of volts?

author: MagicSmoker
author_rank: Super Contributor
timestamp: November 07, 2015, 10:30:09 pm
content: Personally, I'd start checking for the proper voltages on the CRT (filament/heater, grid, screen, 2nd anode [careful - HV!]).Here's a page on troubleshooting Asteroids:http://arcarc.xmission.com/Tech/Asteroid%20Tech/asteroidsrepair.htmlAlso, search for "asteroids manual schematic" and the first hit is the operator/service manual.

author: RobII
author_rank: Regular Contributor
timestamp: November 08, 2015, 01:43:03 am
content: Let me back things up a bit. On the Asteroids PCB there are X and Y output test lugs which is what I have the scope connected to. Currently I have the monitor disconnected at the molex. I want to concentrate on getting game play output on the scope so I can rule out the PCB definitively. Once I can get that part working I can start rebuilding the monitor chassis.

author: mikerj
author_rank: Super Contributor
timestamp: November 08, 2015, 08:40:27 am
content: Quote from: RobII on November 08, 2015, 01:43:03 amYou'll need to connect the Z output (if your scope has one) to a suitable blanking signal otherwise the output will be a mess.

author: RobII
author_rank: Regular Contributor
timestamp: November 08, 2015, 04:28:12 pm
content: Agreed it will look like a mess but will have a definite game play which I do not get right now. Scope does have a z input . All i see on the scope for gameplay is a jumbled mess squished at the left side of the screen as seen in the last few seconds of my video.

author: Andy Watson
author_rank: Super Contributor
timestamp: November 08, 2015, 04:33:28 pm
content: Quote from: RobII on November 08, 2015, 04:28:12 pmSo turn up the gain on the oscilloscope to fill the screen. It looks as if there is some intelligence in those signals - and it looks like it is moving around at typical game playing speed.

author: Macbeth
author_rank: Super Contributor
timestamp: November 09, 2015, 01:32:18 am
content: Yes. Initially the fault was reported as a totally dead screen (or blind screen) but I guess sound, etc ok.Later it turns out the screen isn't totally dead because a centre dot is reported. So the EHT must be there, but the X/Y plates aren't getting voltage and the Z must be turned off otherwise there would be a very bright dot in the centre burning the CRT.There is clearly without a shadow of a doubt gameplay coming from the board - which has to go to the CRT amplifiers. I mean none of that stuff is random noise. If the CRT was displaying similar mess to the 'scope then yes go back and check the game board, but that's not the fault, so why bother checking it further? Clearly its the video amplifiers, and as it's unusual for both to fail at once it must be the amplifier supply that has failed.

author: RobII
author_rank: Regular Contributor
timestamp: November 09, 2015, 01:57:56 am
content: I guess i need to clarify my reasoning. I am checking the output from the game pcb with the scope and unable to get any kind of video output. What i am getting on the scope screen was the same mess I was getting on the game monitor (well very close to it).I was checking voltages for the game pcb op amps, the TL081's are showing good supply voltages + and -15 but the two TL082's are showing a good -15 on the negative supply and -5 for the positive (should be 15 according to the datasheet). I also checked votages to the DAC's a solid -15 but a +15 when the datasheet for them states a supply of only +5. I dont have the Asteroids repair to verify what the voltages should be.

author: tec5c
author_rank: Frequent Contributor
timestamp: November 09, 2015, 02:14:04 am
content: Could you take some photos of the cabinet, inside and out?

author: Macbeth
author_rank: Super Contributor
timestamp: November 09, 2015, 02:21:24 am
content: I give up

author: bitslice
author_rank: Frequent Contributor
timestamp: November 09, 2015, 02:48:59 am
content: There are a few forums which deal specifically in arcade/console machine repair, you might like to check them out.

author: MagicSmoker
author_rank: Super Contributor
timestamp: November 09, 2015, 12:20:35 pm
content: Quote from: Macbeth on November 09, 2015, 01:32:18 amThis is why I said check the grid voltages on the CRT against the values reported in the service manuals... It also wouldn't hurt to check the deflection yoke current waveforms.

author: RobII
author_rank: Regular Contributor
timestamp: November 09, 2015, 01:17:12 pm
content: Sorry to have wasted everyones time. I'm not understanding the logic of checking the CRT voltages when I want to get the game to output properly on my scope first which I have not been able to do.The guys that helped me fix my scope were awesome so I thought I'd start a thread about my game.Thanks again for everyones help. Moving on.

author: MagicSmoker
author_rank: Super Contributor
timestamp: November 09, 2015, 09:35:58 pm
content: Quote from: RobII on November 09, 2015, 01:17:12 pmErr, ok... So the goal is not to fix the game, it's to turn your scope into a monitor for said game?

author: RobII
author_rank: Regular Contributor
timestamp: November 09, 2015, 10:01:15 pm
content: That is the ultimate goal but I want to verify FIRST that the PCB is outputting the proper signals to the scope. No need tearing into the monitor chassis and replacing parts if it's not the issue. Sorry if I didn't make it clear enough. I honestly didn't think what I was asking was that confusing.Step one, is game PCB outputting proper vector info to scope > Yes, issue is the monitor chassis > No, issue is with the game PCB.Quote from: MagicSmoker on November 09, 2015, 09:35:58 pm

author: Macbeth
author_rank: Super Contributor
timestamp: November 09, 2015, 10:06:24 pm
content: Exactly. It appears he starts off saying no output on the CRT at all, so leads us down the garden path. Then states only a centre dot is visible with the brightness turned up, leading us down another twist. Clear evidence of proper game field coming from the board. Now he just wants to display it on his scope all along and isn't interested in the CRT, just wants to see it on the 'scope.Either a fucking troll or an idiot who couldn't just ask "how can I get asteroids to display on my 'scope in X/Y mode?" and has to invent a non working CRT for it instead... and then give a back handed thanks for the help given.

author: TerraHertz
author_rank: Super Contributor
timestamp: November 09, 2015, 10:28:53 pm
content: Probably either the positive or negative supply rail to the output XY amplifiers on the game board has failed.So there is signal, but it's all in one quadrant. Hence the scope XY display up in one corner.Also resulting in the display unit screen protection circuit cutting in, to protect the phosphor from burns.Btw, it isn't just phosphor burns that result from a fully on electron beam sitting in one spot. It will actually drill a hole into the glass. I've seen this happen. Used to service console video games long, long ago.It's a bad idea to even try to see the beam (turning it up, etc) if the drive signals are suspect.I think I *might* have Atari Asteroids schematics, for both the game board and XY monitor. Will have a look sometime today. Aren't they on the net already? The game board schematic is one huge map-sized folded-up sheet, so would be a pain to scan and stitch.Edit: Hmm... can't find the Asteroids schematic, though I think it's just mis-filed, since I'm certain I do have the XY-monitor manual, and maybe the Asteroids schematics are with that.But I did find an Atari Battlezone schematic (similar XY-system.) It's two big map-size sheets, both sides. Probably the Asteroids schematic is 2 sheets too.Also found some crappy photocopies of "ASTEROIDS SELF-TEST and Diagnostics." 5 pages.Will keep looking for the correct schematic a bit more.

author: Andy Watson
author_rank: Super Contributor
timestamp: November 10, 2015, 12:18:31 am
content: Quote from: TerraHertz on November 09, 2015, 10:28:53 pmFor those playing along at home:http://www.mikesarcade.com/arcade/manuals.htmlHave we established whether the scope traces were taken with X10 probes? Even with X10 probes, the signal levels appear to be less than the schematic would suggest.

author: miguelvp
author_rank: Super Contributor
timestamp: November 10, 2015, 12:44:11 am
content: Relevant videos:

author: tec5c
author_rank: Frequent Contributor
timestamp: November 10, 2015, 01:59:51 am
content: Wow, those videos are awesome.I strongly encourage you, RobII, to continue on with this project, despite the waywardness of this thread. With the second video in the previous post, see if you can replicate what he does with just the Y output. This should give you a good indication of what is working and what isn't.Also, as someone previously posted, there are plenty of service manuals available for arcade games online. Do you have the one for your machine?

author: RobII
author_rank: Regular Contributor
timestamp: November 10, 2015, 02:58:53 am
content: I did state in the first post that there was no output on the monitor and I also stated right after that, I want to verify the game PCB is functioning as it should via the scope. Then move to the monitor chassis.I did not intend to "troll" or mislead and I can't apologize enough if my thanks came across as sarcastic in any way. I will be the very first to admit my lack of knowledge about electronics and do appreciate any and all advice given up to this point.I hope we can move past this misunderstanding.Quote from: Macbeth on November 09, 2015, 10:06:24 pm

author: RobII
author_rank: Regular Contributor
timestamp: November 10, 2015, 03:00:17 am
content: Thank you. Grabbed the manuals and yes using x10 probes.Edit: Found schematics herehttp://www.andysarcade.de/asteroids.htmlLooks like the output schematic is herehttp://arcarc.xmission.com/PDF_Arcade_Atari_Kee/Asteroids/Asteroids_DP-143-7th-02B.pdfQuote from: Andy Watson on November 10, 2015, 12:18:31 am

author: RobII
author_rank: Regular Contributor
timestamp: November 10, 2015, 03:03:49 am
content: Thank you for the vid links.I have seen the second one and I am wondering if some of my problem might be my lack of experience using a scope. I get nothing close to what is displayed in the video. I had everything set at .2ms and .2v and switch to XY mode but nothing looks like that.Quote from: miguelvp on November 10, 2015, 12:44:11 am

author: RobII
author_rank: Regular Contributor
timestamp: November 10, 2015, 03:17:17 am
content: Thank you tec5c!! I'm not sure if I am setting my scope incorrectly or if the PCB isn't working.I think I posted some supply voltages I checked for the DAC's and the OP Amps and I inadvertently checked the wrong pins on the TL082's. After double checking, all amps are getting a good supply voltage -15 and +15.Quote from: tec5c on November 10, 2015, 01:59:51 am

author: poot36
author_rank: Frequent Contributor
timestamp: November 10, 2015, 04:59:22 am
content: I would also check out these youtube users videos for general (and advanced) arcade board repairs;https://www.youtube.com/user/arcadeuk/videosandhttps://www.youtube.com/user/retrogamesparty/videos.Especially this one:https://www.youtube.com/watch?v=6iGSOQkUY_0.I would check that all the power supplies are good and do not have more then 200mV or so of ripple on them (use a multimeter in AC volts mode) or your scope in AC coupled mode. If they all check out make sure that the CPU is not constantly in reset and that it has a good quality (5V peak to peak) square wave for the clock input.

author: tec5c
author_rank: Frequent Contributor
timestamp: November 10, 2015, 08:15:56 am
content: Note that the scope in that video isn't set to XY mode. Perhaps this is why you're not getting anything similar to the video?Are you probing the Y output only?

author: TerraHertz
author_rank: Super Contributor
timestamp: November 10, 2015, 01:15:33 pm
content: Do this:* With no input to your scope, set each channel to grid lines, ch1 in the top half, ch 2 in the bottom half. Remember where they are. Set both channels gain to 5V per div. (assuming x1 probes) so the total pp signal should be about 2 divs. Set AC/DC to DC for both channels. What we want to know is the DC range and offset of the XY signals.* Now hook the scope probes on the X & Y outputs of the game board.Q: Are both channels showing some signal SYMMETRICALLY around their zeros? They are supposed to be.If they are both all positive or all negative, there's something in common wrong with the output system.You mentioned the + & - 15V rails are OK. So, one other thing in common to X & Y is the sample and hold control signal SHCON. Read the notes on the schematic. Is that signal doing what it should?How about the INV & NINV signals? These should not be the same, they are logical opposites, always. And in single player mode they should never change.Another thing to check is the outputs of the current to V converter op amps C12 & A21, pins 7. These should be symmetrical around ground too, though since it's before the S&H, they will look very messy.

author: RobII
author_rank: Regular Contributor
timestamp: November 10, 2015, 04:20:48 pm
content: Thanks for the responses all. I will be stuck at work late tonight so no testing will get doneI'll report back though.

author: TerraHertz
author_rank: Super Contributor
timestamp: November 11, 2015, 01:40:44 pm
content: This may or may not be useful. An old document I just scanned: "Asteroids self-test and diagnostics" 380K ZipMainly to send to the Atari game archive sites, since it doesn't seem to be there already.Also some Atari - Asteroids info/repair sites:https://sites.google.com/site/asteroidsrepairlog/Asteroids Type PCB Troubleshooting Noteshttp://gamearchive.askey.org/Video_Games/Manufacturers/Atari/asteroids.htmlhttp://gamearchive.askey.org/Video_Games/Manufacturers/Atari/vector.htmlhttp://www.arcade-museum.com/manuals-videogames/A/Asteroids.pdfAsteroids - Operation maintenance and service manualhttp://www.arcade-museum.com/manuals-videogames/A/AsteroidsDeluxe.man.pdfAsteroidsDeluxe - Operation maintenance and service manualhttp://arcarc.xmission.com/Tech/Asteroid%20Tech/asteroidsrepair.htmlASTEROIDS Troubleshooting Encyclopediahttp://arcarc.xmission.com/Welcome to the ARCade ARChive.

author: RobII
author_rank: Regular Contributor
timestamp: November 12, 2015, 09:07:22 pm
content: I have a few minutes to give some answers.I have tried it both ways but I was probing both X and Y at the same time. I will attempt with just the Y.Quote from: tec5c on November 10, 2015, 08:15:56 am

author: RobII
author_rank: Regular Contributor
timestamp: November 12, 2015, 09:14:21 pm
content: Quote from: TerraHertz on November 10, 2015, 01:15:33 pmI will do this as instructed and report back. I have both x1 and x10 probes.Quote from: TerraHertz on November 10, 2015, 01:15:33 pmWhen I was messing around with it last weekend the signals were not symmetrical but I will check what you are asking and report back.Quote from: TerraHertz on November 10, 2015, 01:15:33 pm

author: RobII
author_rank: Regular Contributor
timestamp: November 28, 2015, 04:53:26 pm
content: Sorry for the delay with any updates. So far here is what I have tested.B12 - pin 5 and 6 (SHCON) -4vD12 - pin 5 and 6 (SHCON) -4vB12 - pin 12 (NINV) .028v pin 13 (INV) -7.73vD12 - pin 12 (NINV) 7.76v pin 13 (INV) -7.74vAs for the symmetry of channels I can't confirm the center. I set it up as TerraHertz stated but when I switched everything on everything shot off the screen so I had to dial them back in view. Here is what I was seeing. X is on top.C12 pin 7 -5vA12 (i'm assuming that's what you meant) pin 7 -4v

author: poot36
author_rank: Frequent Contributor
timestamp: November 29, 2015, 06:42:06 am
content: Could you tell us which controls you used to bring the traces back on the screen when they flew off the screen? You should use the V/div knobs for this adjustment and leave the vertical position knob alone allowing the traces to stay where you originally placed them with no signal input. On both traces you should see roughly the same deveation above and below the no signal input line for each channel. If you do not there is a problem. That near zero volts reading on that one chip pin somewhat concerns me unless it is susposed to be held low when the game is running. If this game has a test mode use it and see if everything else except for the video works.

author: Andy Watson
author_rank: Super Contributor
timestamp: November 29, 2015, 09:22:56 pm
content: If I've interpreted the datasheet correctly, the X-signal on C12, pin7, should range from -4.86 to +4.86. The Y-signal on A12, pin 7, from -3.65 to +4.60V.

author: RobII
author_rank: Regular Contributor
timestamp: November 30, 2015, 02:39:36 am
content: I can call this case closed!!! It's fixed!!!It ended up being a bad voltage regulator, VR3 (7805). It was dumping 15v rather than 5v to the DAC's. I changed it out and it's running almost perfect!!!Only issue I'm having now is some audio hum. I have rebuilt the AR board and the power brick. The hum seems to change intensity if I wiggle the main PCB edge connector. I will see about getting the connector cleaned up.Here's a short video of it working.https://youtu.be/sbt399d4gAkScope outputNice clean sawtooth!!!Thanks to everyone that helped!! It was a bit of a rocky road with some miscommunication but with every ones help, I was able to get this baby working again.

author: TerraHertz
author_rank: Super Contributor
timestamp: December 02, 2015, 01:10:09 am
content: Woohoo!Told you it had to be something in common to both X & Y outputs.The hum is probably due to poor contact on the connector ground pins, plus too long/thin cables to your power supply. But don't expect to get completely pure sound; those things were never designed to be hi-fi.Don't you have some controls rigged up, so you can play it?Here's some details from an old notebook, on a small test controls box I made in 1981.

author: RobII
author_rank: Regular Contributor
timestamp: December 02, 2015, 01:20:47 am
content: You did indeed! Yeah I am going to check all the grounds and clean the edge connector again. Right now the hum is not really obnoxious but gets annoying real quick.I have been playing it. The first pic is the pcb back in the cab and I have the short youtube vid showing it working. I am so glad I stuck to my guns and kept troubleshooting the game pcb. I would have been wasting my time.Now that its working I can start on the cosmetics of the cabinet etc.Another thanks for your help!Sent from my GT-P5210 using Tapatalk

author: RobII
author_rank: Regular Contributor
timestamp: December 06, 2015, 11:30:04 pm
content: I've had a minor issue pop up. When the game was sitting idle for about a week, I fired it up to play it. The bottom half of the screen was oscillating up and down. I pulled the PCB and put the scope on it. Here is what I am seeing.https://youtu.be/wzF6lXGZnOoAfter it has been on for about five minutes, everything is back to normalhttps://youtu.be/LoR1c5H3F3MI started to do a reflow of components in the vector output section. If I tap on the pcb, the screen jumps and get's a little distorted.Any suggestions?

author: TerraHertz
author_rank: Super Contributor
timestamp: December 07, 2015, 01:06:11 am
content: Definitely an analog problem, since the jumping isn't quantized. Probably another supply rail issue.Check your supply rails on the board (with the scope), wiggle edge connectors, anything in sockets, scope probe around the analog section following the wonky Y signal back from the board output through the circuit, until you find where it changes from good to wonky.Edit: Hmm... or something with the Y channel S&H, that only affects the 'down' polarity (can't recall if that's negative or positive.)

author: justanothercanuck
author_rank: Frequent Contributor
timestamp: December 07, 2015, 09:11:01 am
content: have you replaced any capacitors on the board? might be something in the horizontal deflection circuit,because i think asteroids runs with a "tate" (rotated) screen.edit: no it doesn't, check the vertical instead.

author: RobII
author_rank: Regular Contributor
timestamp: December 07, 2015, 04:28:26 pm
content: I personally have not but it does appear they have been replaced at some time. I will double check them tonight. Thanks for the suggestion.Quote from: justanothercanuck on December 07, 2015, 09:11:01 am

author: TerraHertz
author_rank: Super Contributor
timestamp: January 02, 2016, 01:52:10 am
content: Yay! I found my folder containing the Asteroids schematics and the full service manual for the X-Y display.It was stupidly mis-filed.Also 10 pages of photocopied handwritten notes on the vector data format. Lots of detail but not my handwriting, and I can't recall anything about it. Might be from the original game hardware developers, I think.Plus a few handwritten pages by me, apparently trying to summarize. Dated 16/10/81.The schematics already exist online, but I don't think the monitor manual and notes are. Should I bother scanning them?

author: Macbeth
author_rank: Super Contributor
timestamp: January 02, 2016, 02:34:25 am
content: Quote from: TerraHertz on January 02, 2016, 01:52:10 amBut of course! It may well be the only copy left in the world. Damn, my favourite early arcade games of all time are Asteroids, Defender and Galaxians. Absolute classics. Space Invaders never really did it for me. But they are all the original arcade games, and Asteroids the first (commercial) vector game AFAIK.eta: I seem to remember a silly vector game called Battlezone with a tank "turret scope" I had to put my little head in. That was shit but may predate Asteroids?

author: miguelvp
author_rank: Super Contributor
timestamp: January 02, 2016, 02:57:15 am
content: I believe Asteroids where 1st, then Battlezone and Red Baron. I did like them all, but Asteroids was my favourite on vector games.

author: Macbeth
author_rank: Super Contributor
timestamp: January 02, 2016, 04:57:47 am
content: Then of course the colour vector games like Tempest and Star Wars. I think I found Battlezone rubbish because I was too small to peer into that turret viewfinder and it ate all my pocket money!

author: TerraHertz
author_rank: Super Contributor
timestamp: January 03, 2016, 10:38:51 am
content: Here's the scanned Atari Asteroids X-Y monitor service manual. Also those 'possibly from Atari' notes on the vector data format:http://everist.org/archives/scans/Atari_Asteroids/Asteroids_xy_monitor_service.zip 1.8 MBAsteroids_vector_notes.zip 2 MBAsteroids_self_test.zip 376 KBThe manual is for the 14" and 20" models, as used by Leisure & Allied in Australia.Models LAI-KZ-14XYB and LAI-KZ-20XYB.Perhaps the same X-Y monitor would have been used in all markets? Since they weren't exactly a common thing.It's a html doc. In case anyone looking at it doesn't realize, the in-line schematics and board layouts are large thumbnails. Click on them to see the full size pages.

author: miguelvp
author_rank: Super Contributor
timestamp: January 04, 2016, 05:09:35 am
content: Thanks TerraHertz.We do have one at the office among others, and every now and then, they need to be serviced, this might help.Yeah we do have an Arcade room

author: RobII
author_rank: Regular Contributor
timestamp: January 13, 2016, 03:38:01 am
content: Another update. Narrowed the problem down to a failing op amp. I replaced and socketed all four of them and everything is rock solid once again. Thanks for the manual scan/links and the help all.Sent from my GT-P5210 using Tapatalk