Tech: Omega Race help needed - getting closer!

jehuie

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Ok I got the monitor on my Omega Race working. And I found a bad +5 regulator that I replaced and now it's working....kind of!

It has a few issues:

1) The game images have horizontal gaps in the graphics as can be seen in the video below.

2) The image is backward. The PCB came from a different Omega Race game...is there a setting somewhere for this?

3) The image is dim. I have to brighten it up quite a bit to see the image and then I get trace lines and bright spots. The monitor looks fine and operates with the brightness much lower when plugged into my Asteroids Deluxe.

If I put the game in test mode I get 8 beeps and a pause, over and over. Is that normal?

Here's the video: http://vimeo.com/49528205

(Not sure how to embed vimeo video's on this forum.)

Any tips? Thanks guys!
 
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Ooh, ooh, I know this one! Well, part of it anyway - the image is backwards because you're looking directly at the monitor. When it's installed in the cab, you'll be looking at a reflected image from the two way mirror in the cab. As for your other questions, I got nothin'...

Congrats on getting your monitor working, though. You've inspired me to brave the heat in my garage and work on my OR. Maybe. :)
 
Ooh, ooh, I know this one! Well, part of it anyway - the image is backwards because you're looking directly at the monitor. When it's installed in the cab, you'll be looking at a reflected image from the two way mirror in the cab. As for your other questions, I got nothin'...

Congrats on getting your monitor working, though. You've inspired me to brave the heat in my garage and work on my OR. Maybe. :)

Holy crap, I forgot all about that. Heh. Thanks! And good luck on yours too. I may have some extra parts for the board when I'm done....maybe....if you need anything.
 
Ok I got the monitor on my Omega Race working. And I found a bad +5 regulator that I replaced and now it's working....kind of!

It has a few issues:

1) The game images have horizontal gaps in the graphics as can be seen in the video below.

2) The image is backward. The PCB came from a different Omega Race game...is there a setting somewhere for this?

3) The image is dim. I have to brighten it up quite a bit to see the image and then I get trace lines and bright spots. The monitor looks fine and operates with the brightness much lower when plugged into my Asteroids Deluxe.

If I put the game in test mode I get 8 beeps and a pause, over and over. Is that normal?

The 8 beeps means the battery backup RAM is failing... happens on lots of boards. I'm having the same issue myself, even on a brand new board!

Dim image is a problem with the Z drive. Check the three transistors Q204, Q205, Q206 up around chip A1. They're cheap 3904s and a 3906 so you could just replace the lot.

Backward image may be flipped back by the mirror or not... see pages 23-24 of the FAQ.

Gaps in the Y axis could be a bad DAC if it was damaged by the 7805, or could be further back in the vector counters, buffers or latches. If you have a logic probe compare the pins on the Y channel with those of the X. DACs (C5 and B5) data pins are 4 thru 13, then latches (D5 and A5) pins 3,4,7,8,13,14,17,18 and D6 pins 3,14 vs. D6 pins 4,6. Next are the multiplexers (D4, E4, F4 and A4, B4, C4) pins 2,5,11,14 and before those the counters (D3, E3, F3 and A3, B3, C3) pins 1,9,10,15. They should all be pulsing - look for one that isn't or that is substantially different between Y and X.
 
The 8 beeps means the battery backup RAM is failing... happens on lots of boards. I'm having the same issue myself, even on a brand new board!

Dim image is a problem with the Z drive. Check the three transistors Q204, Q205, Q206 up around chip A1. They're cheap 3904s and a 3906 so you could just replace the lot.

Backward image may be flipped back by the mirror or not... see pages 23-24 of the FAQ.

Gaps in the Y axis could be a bad DAC if it was damaged by the 7805, or could be further back in the vector counters, buffers or latches. If you have a logic probe compare the pins on the Y channel with those of the X. DACs (C5 and B5) data pins are 4 thru 13, then latches (D5 and A5) pins 3,4,7,8,13,14,17,18 and D6 pins 3,14 vs. D6 pins 4,6. Next are the multiplexers (D4, E4, F4 and A4, B4, C4) pins 2,5,11,14 and before those the counters (D3, E3, F3 and A3, B3, C3) pins 1,9,10,15. They should all be pulsing - look for one that isn't or that is substantially different between Y and X.

Cool, I'll run to Fry's and see if they have those transistors to start with. And it's not a problem to swap the DAC's is it? Just to see if the problem changes when I do so?
 
Cool, I'll run to Fry's and see if they have those transistors to start with. And it's not a problem to swap the DAC's is it? Just to see if the problem changes when I do so?

Swapping the DACs is a great idea. If the missing bands then run from top to bottom then you've found the problem. If not then it'll be on to testing your way back through the listed chips.
 
Good call on the transistors Douglasgb! I took a look and one was actually missing. :) I just happened to have a few spares that I threw in there and it fixed the brightness issue. And....I swapped out one of the DAC's with an extra that I had and it fixed the gaps in the graphics!

So I actually played my first game on the thing today!

Still has a few issues though. The major two things are 1) I have the Y-size control maxed out but the game isn't filling up the screen. It covers maybe 2/3 of the screen vertically but won't stretch any more. And 2) It's still doing the pulsing screen thing.

So I can try swapping out the X and Y-size pots from one of my other PCB's and see if it behaves any differently. But otherwise I think I'm in good shape now.

The knowledge around here is pretty astounding. Thanks again guys!

John
 
Good call on the transistors Douglasgb! I took a look and one was actually missing. :) I just happened to have a few spares that I threw in there and it fixed the brightness issue. And....I swapped out one of the DAC's with an extra that I had and it fixed the gaps in the graphics!

So I actually played my first game on the thing today!

Still has a few issues though. The major two things are 1) I have the Y-size control maxed out but the game isn't filling up the screen. It covers maybe 2/3 of the screen vertically but won't stretch any more. And 2) It's still doing the pulsing screen thing.

So I can try swapping out the X and Y-size pots from one of my other PCB's and see if it behaves any differently.

Awesome. It's a great game. Try a new TL082 at A8, then the TL081 at A7 for the vertical size issue. Pulsing I thought was your monitor since it does it with Asteroids, too?
 
Awesome. It's a great game. Try a new TL082 at A8, then the TL081 at A7 for the vertical size issue. Pulsing I thought was your monitor since it does it with Asteroids, too?

Yes, the pulsing is definitely the monitor. I'll check those...thanks!
 
Awesome. It's a great game. Try a new TL082 at A8, then the TL081 at A7 for the vertical size issue. Pulsing I thought was your monitor since it does it with Asteroids, too?

Ok I swapped out both the TL081 and TL082 (for both the horizontal and vertical just to be safe) and it still looks the same. I see some resistors close to there. Could a resistor failure cause something like this as well?
 
Ok I swapped out both the TL081 and TL082 (for both the horizontal and vertical just to be safe) and it still looks the same. I see some resistors close to there. Could a resistor failure cause something like this as well?

Oh that's good because the Y size goes through B/C7 and B/C8, sorry. Is the ceramic disc capacitor C211 present just to the right of B/C8 to match C212 near A8?

But yeah the relevant resistors are R258, R241 and R243 should be 10K, R240 should be 15K, R239 should be 6.8K, and R238 should be 2.2K

Here's a PDF to help locate components. You can search for R238 for example and it will highlight the part:

http://www.gauck.com/arcade/repror/reprOR map.pdf
 
I was so close I could taste it...and then it all slipped away. :(

Status so far: I pulled the HV diode back out to be sure it was making a good connection hoping it would fix the pulsing issue....and it did! Yay.

So then I looked to be sure that cap you asked about was still there. It is. And I went to start checking those resistors. I lifted one leg out of R258 and checked it. It measured 9.7K...is that ok? Not sure but I thought so and soldered it back in.

Then I noticed something that seemed rather important.....Q203 was missing! I figured this was the cause of all my woes and went and grabbed one off my spare O.R. board and soldered it into place.

Put it all back together and tried it out and....it's WAY worse now. :(

Not only is it still shrunken vertically, but now all the graphics have bad jitters and no longer look quite right. It's hard to explain without video so I'll have to try to take some. But I can't tonight.

Argh.

Any ideas what I might have hosed? I suppose it's possible that my Q203 that I robbed from the other board might be bad and causing this? Or something.
 
Was Q203 missing or blown apart?

It is involved in the +/- 8.2 volt supply coming from the +/- 15v VREGs and going into the 4016 switches. If your regulators were bad I'd guess you'd have no picture.

Installing the missing Q203 may have turned on a 4016 that's now working badly where before it wasn't working at all.
 
Was Q203 missing or blown apart?

It is involved in the +/- 8.2 volt supply coming from the +/- 15v VREGs and going into the 4016 switches. If your regulators were bad I'd guess you'd have no picture.

Installing the missing Q203 may have turned on a 4016 that's now working badly where before it wasn't working at all.

It was missing....like it had been desoldered and used on another board perhaps. I'll swing by Rad Shack in a bit and see if they have these in stock. Are you saying I should replace the 4016 also? Not sure what that even is yet!
 
It was missing....like it had been desoldered and used on another board perhaps. I'll swing by Rad Shack in a bit and see if they have these in stock. Are you saying I should replace the 4016 also? Not sure what that even is yet!

Well let's see the video, but yeah it could be those chips at A6 and B6.
 
Well let's see the video, but yeah it could be those chips at A6 and B6.

Ok I swapped out the 3 transistors and I bought the chips that go in A6 and B6 but have not put them in yet. I am getting better at swapping chips but I still don't like to do it unless really necessary because I don't want to hose something else up. :)

After putting the transistors in I tried it again and the shakiness is gone. But it's still squished down like it was before and I have banding going through the objects. I took some video but haven't posted it because it looks quite a bit like what it looked like in the previous video. I fixed it last time by swapping in another DAC. I thought about doing this again to see if I somehow zapped another DAC but they don't come cheap so I'm not sure if I should or not. What do you think? Would replacing the transistor somehow fry a DAC?
 
I think I'm going to grab a DAC off the other board and swap it in to see if it helps. Hopefully I don't just ruin another one.
 
Yes and yes. Just concerned that whatever caused the last 2 dac's to go bad will ruin the next one too. I changed the size pot on the game pcb, not the monitor since it looked fine on asteroids deluxe.
 
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