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Omega Race PCB repair #2
- Thread starter omegaman
- Start date
The set arrived back at my place today, thanks Omegaman! Once I get some PCB brackets I'll give it a test in my cab. I've left positive feedback to follow through and complete the transaction. When I get everything together, I'll post a picture of it in my cab.
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omegaman
Active member
Glad it arrived OK, fingers crossed the others turn up very soon. Thanks for the feedback 
I had a burning desire to test this out in my cab last night with my spare sound board.
At first power up I had a great working game with X -Y main board pots that needed adjustment. I also had no sound.
It turns out I had a replacement 2732 EPROM where a 2716 should have been. I just burned the correct chip and code and have sound.
I went to adjust the main board pots and my game suddenly went blank. I made sure so follow static safety precautions and nothing bit me from the game board, I've done this a lot on my set. I went around and reseated all socketed chips I figure something simple happened during shipping, after two trips over the Atlantic my box was beat.
I also found a really poor excuse for a socket on one of the DACS. I replaced that with a nice one. I was the one that had originally installed the socket several years ago.
I just have this really bad feeling I somehow made an expensive paper weight and only got a minute of play.
No real errors though. The spot killer is on is seems, no video. I can coin the game but it will not play blind. Looks like self test won't even start. I get some beeps, sometimes six (one or two bad RAM chips) sometimes eight (bad BB ram). Damn. These beep codes don't make any sense, all of these parts are new.
My old still working set works 100% in the cab, so I know nothing in that is bad.
What rotten luck.
At first power up I had a great working game with X -Y main board pots that needed adjustment. I also had no sound.
It turns out I had a replacement 2732 EPROM where a 2716 should have been. I just burned the correct chip and code and have sound.
I went to adjust the main board pots and my game suddenly went blank. I made sure so follow static safety precautions and nothing bit me from the game board, I've done this a lot on my set. I went around and reseated all socketed chips I figure something simple happened during shipping, after two trips over the Atlantic my box was beat.
I also found a really poor excuse for a socket on one of the DACS. I replaced that with a nice one. I was the one that had originally installed the socket several years ago.
I just have this really bad feeling I somehow made an expensive paper weight and only got a minute of play.
No real errors though. The spot killer is on is seems, no video. I can coin the game but it will not play blind. Looks like self test won't even start. I get some beeps, sometimes six (one or two bad RAM chips) sometimes eight (bad BB ram). Damn. These beep codes don't make any sense, all of these parts are new.
My old still working set works 100% in the cab, so I know nothing in that is bad.
What rotten luck.
tester007
Well-known member
Omega, would it be possible to cut a comparator adapter off, wire it to a socket you could put in the ic tester and check chips onboard?
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omegaman
Active member
Sounds like your power supply may have gone bad. Have you checked the +5v at the board?
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omegaman
Active member
Sorry I'm confused by your question. The comparator tests chips on board.......Ah i see what you are getting at. No I think the IC would need to be isolated first. ABI do make an in circuit tester. I will get my hands on 1 one day
I just missed a few on ebay a few weeks ago
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omegaman
Active member
I'm sure we can get it running.....random ram errors sound like low power supply voltage. Unplug your monitor for now and leave it in test mode. Check the +5v level is good at the game PCB first. You can check it across the silver capacitor just about the edge connector.
Have you got a logic probe?
Have you got a logic probe?
Well, my other PCB powers fine, but I can look around at the voltages. It has been several years since it was adjusted, which I did after I replaced the caps on the power board and my first set. Your can see the new caps in the pics I provided in Malace's thread.
I do have a logic probe but I have only attempted to use it once.
None of the pins are touching on the solder side of the PCB.
I've thought on it, the metal connector that holds the two boards together is aluminum and was sitting on the ground (plate) around the board since the mask is gone on this board. I don't see how that could have shorted anything though.
I'll report back after I've checked the voltages.
I do have a logic probe but I have only attempted to use it once.
None of the pins are touching on the solder side of the PCB.
I've thought on it, the metal connector that holds the two boards together is aluminum and was sitting on the ground (plate) around the board since the mask is gone on this board. I don't see how that could have shorted anything though.
I'll report back after I've checked the voltages.
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omegaman
Active member
The metal plate attaches to ground so that's fine. When you coin it up, do the 2 start LED's flash? then adding more credits makes all 4 LED's flash?
Okay, at the cap it was 4.7V
I was able to increase the pot to 4.9 to 5.0V but no more. Looks like my power supply has gotten weak even with the new caps. The coin door lights and marquee have never been functional.
I saw your post on adding jumper wires to the power supply to test without a board connected. Can I use old capacitor legs instead of insulated wire?
Where are the test points after this mod?
I was able to increase the pot to 4.9 to 5.0V but no more. Looks like my power supply has gotten weak even with the new caps. The coin door lights and marquee have never been functional.
I saw your post on adding jumper wires to the power supply to test without a board connected. Can I use old capacitor legs instead of insulated wire?
Where are the test points after this mod?
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omegaman
Active member
They run fine at 4.7 but closer to 5v is better. Right that's that out of the way. in game mode does it reset or do the player lights flash when you add credit? If they don't stick it in test mode and check to see how many times the LED's flash. You say you have sound now right?
I'm wondering if something on your sound board is causing the problem....have you got another sound PCB?
OOOPS Just read your other post OK its good that you can add credits, sounds like it may be resetting from time to time...It could be the sound PCB where it plugs into the socket on the main pcb. Clean the edge connector with an eraser and give it another go. Once you can coin it up and play it then we can look at the video output section.
I'm wondering if something on your sound board is causing the problem....have you got another sound PCB?
OOOPS Just read your other post
OK its good that you can add credits, sounds like it may be resetting from time to time...It could be the sound PCB where it plugs into the socket on the main pcb. Clean the edge connector with an eraser and give it another go. Once you can coin it up and play it then we can look at the video output section.
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Before I left this morning I swapped sound boards. I got:
1. I could coin the game enough times to get all four LEDs flashing. After each coin I got a partial coin up tone. The game would not start when the LEDs were pressed.
2. Throwing it into test mode got me four flashing LEDs. There was no sound after each flash. They flashed eight times in a row before resetting. The manual says this is BBU ram (if I'm reading it right).
Odd, my good set flags this RAM as bad too, but plays perfect. When I first got this set, all tests passed okay.
EDIT: Is there a good ground test point to tie my black lead (and possibly future logic probe ground) to somewhere in the cab? I always have to break out the schematics in the manual to find anything on this game.
1. I could coin the game enough times to get all four LEDs flashing. After each coin I got a partial coin up tone. The game would not start when the LEDs were pressed.
2. Throwing it into test mode got me four flashing LEDs. There was no sound after each flash. They flashed eight times in a row before resetting. The manual says this is BBU ram (if I'm reading it right).
Odd, my good set flags this RAM as bad too, but plays perfect. When I first got this set, all tests passed okay.
EDIT: Is there a good ground test point to tie my black lead (and possibly future logic probe ground) to somewhere in the cab? I always have to break out the schematics in the manual to find anything on this game.
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omegaman
Active member
BBU will show fail as it probably has corrupt data stuck in it. If you remove the BBU ram carefully then put it back in you will probably find it passes. The game will play find even with the chip removed.
I always attach my logic probe across that capacitor I mentioned, nice and easy clipping it to each leg.
I always attach my logic probe across that capacitor I mentioned, nice and easy clipping it to each leg.
Uploaded my first youtube video of the problems. Sorry for the length, camera work, lighting...heck, the whole thing. It seems like the audio stream is out of sync too.
http://www.youtube.com/watch?v=plYL5XlCKmY
http://www.youtube.com/watch?v=plYL5XlCKmY
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omegaman
Active member
Dude switch the light on! why are you in the dark?
Anyway, that is error reporting not credit flashes. Can you switch it to test mode.....hold the camera above the start LED's and switch the game on. Leave it filming until you see a long pause and the numbers start over again. I would say its the sound board causing the problem as I only had the main board and it was tested for hours before being sent back. Have you got any spare ram you can fit to the sound board?
why are you in the dark?Anyway, that is error reporting not credit flashes. Can you switch it to test mode.....hold the camera above the start LED's and switch the game on. Leave it filming until you see a long pause and the numbers start over again. I would say its the sound board causing the problem as I only had the main board and it was tested for hours before being sent back. Have you got any spare ram you can fit to the sound board?
tester007
Well-known member
Sorry I'm confused by your question. The comparator tests chips on board.......Ah i see what you are getting at. No I think the IC would need to be isolated first. ABI do make an in circuit tester. I will get my hands on 1 one day
What is the model number? Get tired of swapping cards and/or chips in comparator and of course finding a couple of the rare ttl's on the pcb you don't happen to have.
I was thinking on this and I'm going to do what I've always done in this situation: move socketed chips from the bad set to the good set until I find the bad chips. I am convinced something went very wrong during that minute this repaired board was plugged in my machine.
I have complete confidence both sound boards are okay, I've swapped them between sets and they work perfectly. My issue is with this repaired main board.
Now, let's have some fun*
Okay, so I lowered the voltage back to 4.7V at the board for my working set. Check.
I have video and can play a pefect game. Check.
I pick my first victims, these tiny eight pin chips near the two pots I was adjusting. Check.
* This is not fun.
I have complete confidence both sound boards are okay, I've swapped them between sets and they work perfectly. My issue is with this repaired main board.
Now, let's have some fun*
Okay, so I lowered the voltage back to 4.7V at the board for my working set. Check.
I have video and can play a pefect game. Check.
I pick my first victims, these tiny eight pin chips near the two pots I was adjusting. Check.
* This is not fun.
