kb0jjn
New member
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Please post all monitor technical topics in the Technical - Videogames - Monitors section, not in the General Help section.
Omega Race - CAP >BOOOM!<
- Thread starter FrizzleFried
- Start date
OP
OP
Progress....
I re-checked the PS... 5V is at 5VDC, 12V is at 11.55VDC, 18VAC is at 18VAC exatly... 8V unregulated is at 9.5V, not sure how to change that... being it's unregulated.
After replacing the 2 diodes and power regulator and caps the cap at C106 DOES NOT blow any longer. I ran the board for about 5 minutes without issue without the monitor plugged in. I plugged the monitor in and C106 still didn' pop though the image is jacked up on screen. The game plays blind... full audio, controls seem to work and you can see movement in the jacked up video.
Where to go next? I am guessing I screwed up a chip or two.
I know it's the PCB as I tested on my BZ monitor and got the same jacked video.
I re-checked the PS... 5V is at 5VDC, 12V is at 11.55VDC, 18VAC is at 18VAC exatly... 8V unregulated is at 9.5V, not sure how to change that... being it's unregulated.
After replacing the 2 diodes and power regulator and caps the cap at C106 DOES NOT blow any longer. I ran the board for about 5 minutes without issue without the monitor plugged in. I plugged the monitor in and C106 still didn' pop though the image is jacked up on screen. The game plays blind... full audio, controls seem to work and you can see movement in the jacked up video.
Where to go next? I am guessing I screwed up a chip or two.
I know it's the PCB as I tested on my BZ monitor and got the same jacked video.
PM Omegaman?
OP
OP
PMed and emailed 3 days ago. I'm guessing he's been busy.
Womble
Well-known member
Post a video of the screen?
OP
OP
Will take one tonight...
I did a "heat check" and found 3 hottish chips... replaced them all from the parts board with no luck. I replaced the 4 socketed ROM chips for the hell of it... no change...
I did a "heat check" and found 3 hottish chips... replaced them all from the parts board with no luck. I replaced the 4 socketed ROM chips for the hell of it... no change...
Womble
Well-known member
Shot-gunning boards will rarely work I'm afraid, you can tell a lot from the screen tho.
OP
OP
Uploading a video now...
Womble
Well-known member
Ah, didnt realise it was a vector game, thats out of my dept I'm afraid, hopefully one of the vector guys can help.
One thing to check is to follow the downsteam of the blown voltage regulator and see where that goes, does it only connect to the board in one place or two? Clearly the board is undamaged enough to actually run the game so potentially most of it is ok, check where else it goes as that would have been the path of destruction.
One thing to check is to follow the downsteam of the blown voltage regulator and see where that goes, does it only connect to the board in one place or two? Clearly the board is undamaged enough to actually run the game so potentially most of it is ok, check where else it goes as that would have been the path of destruction.
Friz...
STOP.
Don't fuck around with socketed ROMs, etc... It's playing blind so those aren't the problem.
THINK!
What voltage was messed up?
THE -15V SOURCE...
So what do you do?
YOU REPLACE THINGS THAT WERE POWERD BY THE 15V SOURCE.
Op Amps, DACs, etc... Look at the damn schematic.
STOP.
Don't fuck around with socketed ROMs, etc... It's playing blind so those aren't the problem.
THINK!
What voltage was messed up?
THE -15V SOURCE...
So what do you do?
YOU REPLACE THINGS THAT WERE POWERD BY THE 15V SOURCE.
Op Amps, DACs, etc... Look at the damn schematic.
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OP
OP
Unfortunately this boardset not one, not two, not three, not four, not 5 but 6 different connectors... fun, huh?
OP
OP
As if I know how to read a freakin schematic. I tried... trust me... I tried... and I am still trying. PS: I couldn't tell you what an OP AMP looks like vs a freakin' resistor.
TL081, TL082, AD561J (expensive! I have 21 of 'em in stock for $20 each, tested NOS)...
These are the parts you need to look at. These are the parts powered by the -15v source.
These are the parts you need to look at. These are the parts powered by the -15v source.
OP
OP
Welp,
I changed out 2 TL081 and 2 TL082 as well as both AD561J from the parts board to the previously working board and...
...no change. At all.
Looking at the above image of the schematic, it appears that transistor that went to pot also drives the -8.2v... time to look there I suppose?
Womble
Well-known member
Yep - in these cases you it get a cascade of failures rippling across the circuit until something decides to fail open and stop the destruction, hopefully close enough to the original fault that it disconnects all parallel paths of damage. You often have to go several components deep to find the point where the carnage ends.
Are you sure the parts are good on the parts board?
OP
OP
No ... not 100%... but being that I am getting the exact same symptoms... I'm guessing the chances are better that they are than they aren't.
Any way to check the parts?
EDIT: What I mean is... this particular issue is pretty unique I'm assuming... I find zero information online about it. Being that we know it's a pretty unique issue rather than a known "reoccurring" issue, one is more inclined to assume that parts pulled off a clean parts board are more likely OK than not. I'm not too keen on shelling out $40 (there are two) for a couple of chips that may or may not be OK... but are more than likely OK because each has been replaced as well resulting in the same result on-screen.
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OP
OP
Anyone with any experience in this willing to look at it?
omegaman
Active member
Just caught up on this thread. Reading on my phone so sorry for any typos. Channelmanic has been spot on so far. Only thing I would do now is change B6 and A6 both 4016's that's probably the problem. Don't mess with other areas of the board right now as it seems to be fine up to the vector output stage.
Have you checked all the regulators and made sure you have the + and - 15v supplies at the op amps and the +8.2 -8.2 at q202.
Have you checked all the regulators and made sure you have the + and - 15v supplies at the op amps and the +8.2 -8.2 at q202.
OP
OP
I assume I can check up to Q202 by metering from the ground of the regulator to the front side of q202?
Which pin on the op amp is the positive lead where I measure to? I am guessing the schematic will help... no time to check right now though. Work. Gotta love it.
Thanks ... i'll start by checking the voltage then, if I have proper voltage to the amps/diode i'll swap out the 4016's.
