Shelly Posted February 16, 2006 Share Posted February 16, 2006 My upright Centipede was accidentally unplugged a few months ago and when plugged back in, the screen showed garbage (misc symbols, numbers and letters flickering), the audio hummed in strange pitches and the coin counters clicked intermittently. Could not put the machine into test mode as flicking the test switch had no impact at all. Took out the board and cleaned the MPU card connecters with an eraser, popped it back in and machine worked fine. Inevitably, it was accidentally unplugged again, with same symptoms appearing after trying to turn it back on. Cleaning MPU connecters did not work this time. Do these symptoms sound familiar to anyone, and if so, any suggestions? Quote Link to comment Share on other sites More sharing options...
[d2f]Iggy*SJB Posted February 17, 2006 Share Posted February 17, 2006 Well, I don't have one of those machines....but the best thing I can offer up is to test the power supply, and all relevant connections. You might also want to check and make sure all the wires are in good shape, and are firmly connected to the connectors(use a multi-meter and to a pin-by-pin check). I know it's a lot of work, but that's about all I can think of. Oh, you might also check the PCB, and make sure any/all socketed chips are seated well. Quote Link to comment Share on other sites More sharing options...
bjk7382 Posted February 17, 2006 Share Posted February 17, 2006 Well, I don't have one of those machines....but the best thing I can offer up is to test the power supply, and all relevant connections. You might also want to check and make sure all the wires are in good shape, and are firmly connected to the connectors(use a multi-meter and to a pin-by-pin check). I know it's a lot of work, but that's about all I can think of.Oh, you might also check the PCB, and make sure any/all socketed chips are seated well. 1019571[/snapback] That is the advice that I was going to give. Check all your voltages at the circuit board, and make sure your socketed chips have clean pins. Just don't break any pins off. Quote Link to comment Share on other sites More sharing options...
Cassidy Nolen Posted February 17, 2006 Share Posted February 17, 2006 I've seen the big blue cap go bad quite frequently lately. Its funny how just a few more years really did them in (they never went bad when I first worked on games in 98/99). I would suggest a new one regardless. They are not expensive and its just a maintenance item at this point in time. HTH, Cassidy Quote Link to comment Share on other sites More sharing options...
ttontis Posted February 17, 2006 Share Posted February 17, 2006 Cap safety: **** Before you touch a cap make sure you have discharged it and done so safely. Not doing so could hurt you and your equipment. **** Only two things can happen to a capacitor: 1. It may open up, removing itself completely from the circuit. 2. It may develop an internal short circuit. This means that it begins to pass current as though it were a resistor or a direct short. You can check a capacitor you suspect of being leaky with an ohmmeter; if it reads less than 500 kilohms, it is more than likely bad. However, capacitor troubles are difficult to find since they may appear intermittently or only under operating voltages. Therefore, the best check for a faulty capacitor is to replace it with one you know to be good. The other component to look at is the transformer, there are three or four taps that come off the step down side. (I am not sure but I think each line/tap has a fuse check them if they are there.) If one of the windings is bad you are not going to get enough or you are going to get too much. If there is a paper label around the transformer look for burn marks, if there is no label look for some discoloration in the acrylic coating they put on the wires. If the turns of a winding are shorted together, you may not be able to detect a difference in winding resistance. Therefore, you need to connect a good transformer in the place of the old one and see if the symptoms are eliminated. Ted Quote Link to comment Share on other sites More sharing options...
Shelly Posted February 18, 2006 Author Share Posted February 18, 2006 Wow, thanks for all the advice. The friend who is helping me out with this is more of a pinball guy, so I'm sure this is helpful information. Quote Link to comment Share on other sites More sharing options...
Shelly Posted March 5, 2006 Author Share Posted March 5, 2006 Well, we took the PCB board out and popped it into another Centipede game and it worked fine....all voltages on that board are correct (checked the test points). We can rule out the PCB board as a problem and the game still has same symptoms: "garbage" on screen, coin counters clicking, strange audio, etc. My friend is focusing on the wires coming from the coin slot areas on the door and connecting to the PCB board and plans to check continuity on these. He thinks the game is somehow "trying" to start up, but something is preventing this. Any thoughts?? Quote Link to comment Share on other sites More sharing options...
Shelly Posted March 5, 2006 Author Share Posted March 5, 2006 Well, um, after opening the console containing the trac ball/player buttons and cleaning those connections, the game works fine.....??? Go figure! Thanks for all the helpful responses! Quote Link to comment Share on other sites More sharing options...
[d2f]Iggy*SJB Posted March 7, 2006 Share Posted March 7, 2006 Probably some grime causing a short, and thus making it fail it's power-on self test. Quote Link to comment Share on other sites More sharing options...
Cassidy Nolen Posted March 9, 2006 Share Posted March 9, 2006 I'd bet money on that cap. Cap removal; with the PCB unplugged from the harness, I have always just used an insulated screwdriver and touched the two screws on the top to short it out. Frankly, the one he has is no good or it would let him play the game! Obviously this is done with the machine unplugged. If its not the cap you have a power supply issue most likely. I have seen them be related though (get funny voltage issues because of AC on the DC lines, etc). I've seen coin counters, lights and ticket counters cause trouble too but about 99% of the time its not the case. Its the best 10 buck insurance you can find. Cassidy Quote Link to comment Share on other sites More sharing options...
Curt Vendel Posted March 11, 2006 Share Posted March 11, 2006 Most likely it is a p/w issue, I had the same thing happen to my Asteroids and Missile Command ur's, both needed new caps, but also on the Missile Command it needed the two rectifiers replaced as well. Curt I've seen the big blue cap go bad quite frequently lately. Its funny how just a few more years really did them in (they never went bad when I first worked on games in 98/99). I would suggest a new one regardless. They are not expensive and its just a maintenance item at this point in time. HTH, Cassidy 1019824[/snapback] Quote Link to comment Share on other sites More sharing options...
Shelly Posted March 24, 2006 Author Share Posted March 24, 2006 I'll keep the cap idea in mind in case I have any more trouble. I'm just really glad she's up and running again after months of sitting dark, especially with a bright happy pinball machine working fine in the other corner of the game room. Oh, and I'm a "she" as well . Quote Link to comment Share on other sites More sharing options...
Shelly Posted August 1, 2006 Author Share Posted August 1, 2006 Well, wouldn't you know it, when we took a chance and unplugged the game to replace the old burned out monitor it now has the original symptoms again. I had someone else take a look at it and he is convinced it is the big blue cap. Since it is such a cheap "maintenance" item and I have nowhere else to turn, I'll be replacing it, but am still wondering why the game would work intermittently with this part having gone bad. Wouldn't it just stop working period and never come back again if this item were bad??? Quote Link to comment Share on other sites More sharing options...
tta583 Posted August 1, 2006 Share Posted August 1, 2006 Where did you get the cap from? May I make a suggestion? http://www.therealbobroberts.net/parts.html#atari Cap, new fuse block and quick disconnects, and the bridge rectifier. http://www.therealbobroberts.net/atarikit.jpg I throw Bob's links around a lot. I am not associated with him, just a happy customer!! he always seems to have a kit to take care to the common things that kill old games. Quote Link to comment Share on other sites More sharing options...
Shelly Posted August 2, 2006 Author Share Posted August 2, 2006 Do you suggest I order a cap and the additional parts mentioned, just to cover all bases? And can I order from the website identifying my game as an upright Centipede (is that "atarikit' interchangeable among Atari games??), or do I need to get specific numbers off the old parts? Thanks for your help! Quote Link to comment Share on other sites More sharing options...
Shelly Posted November 12, 2006 Author Share Posted November 12, 2006 Hi Everyone, Alas, it was the "big blue cap" as after we replaced it, the game fired up immediately...HOWever, something new is amiss because when we try to play it, the opening screen contains only one vertical row of mushrooms (to shoot at) all the way down the left side. There are no mushrooms at all in the middle of the screen (only when you fire at the centipede coming down and it leaves a few) and also there is no sound (just a hum from the speakers when the volume is turned up all the way). I suspect there is something wrong with the game's software and am tempted to just purchase a whole new board that is currently available on ebay...but I thought I'd run these symptoms by the experts. Any ideas?? Thanks!! Quote Link to comment Share on other sites More sharing options...
kenfused Posted November 12, 2006 Share Posted November 12, 2006 Hi Everyone, Alas, it was the "big blue cap" as after we replaced it, the game fired up immediately...HOWever, something new is amiss because when we try to play it, the opening screen contains only one vertical row of mushrooms (to shoot at) all the way down the left side. There are no mushrooms at all in the middle of the screen (only when you fire at the centipede coming down and it leaves a few) and also there is no sound (just a hum from the speakers when the volume is turned up all the way). I suspect there is something wrong with the game's software and am tempted to just purchase a whole new board that is currently available on ebay...but I thought I'd run these symptoms by the experts. Any ideas?? Thanks!! POKEY chip maybe? Wonder if the game might use POKEY's random number generator for placing the mushrooms? Quote Link to comment Share on other sites More sharing options...
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