Omega Race - CAP >BOOOM!<

FrizzleFried

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Omega Race was working fine yesterday. I turned it off working fine.

Today I go out to the game room. I fire up Omega Race. I hear a "click" i normally don't hear.... and after about 20 seconds the screen come up and it's jacked up... there are squiggles everywhere in the middle-top-left area. The LED's are flashing as normal.

DAMN!

So I power down. I power back up to the same screen.

DAMN!

I hit P1 START to see what happens and as soon as I hit the button...

>BOOOOOOM<

Almost as loud as a friggin' .22 or so.

I power down immediately and open the back to find this:

attachment.php


The 470MF/35V cap right behind the edge connector exploded! What a strange smell. Anyway... it took out the resistor directly above it and the LED as well. I assume the LED isn't a big deal and the resistor can be re-attached (it' disconnected one side).

I can, of course, replace the CAP... but before I do so I want to find out what people think...

Did something CAUSE this cap to explode other than age?

Should I drop the one I have from another board set (non working) in to it to see what it does? Do caps "explode" when they go bad at times? What are the chances the cap went bad rather than there be something "up stream" that caused the cap to explode? If it IS likely something else failing causing the cap to explode... any ideas on what/where to look?

Where should I go from here?
 
Is the kit available on his site or do I have to ask for it?

This is the cap that exploded:

470uf 35V, H10 (by edge connector)

I can't imagine a simple "failed cap" would explode like that, but what the hell could have gone wrong from last night when it worked great at turn off... to when I turned on the game this afternoon?
 
Yes old age can do this, as they age some capacitors gain resistance which makes them run hotter and hotter until they just blow. If you had seen the cap beforehand the plastic sleeving on it would probably have shrunk back like heatshrink. Just replace it with a new one, pay careful attention to the polarity of the capacitor, get it the wrong way round and it will do the same thing again - instantly.

Yes the smell is pretty weird, the X2 cap across the mains in my Oscope failed a year or so back and it absolutely stank, on a hot day i can still smell it when the scope is on even after I cleaned up the sticky black tar that it blew everywhere.

If there are other caps of the same rating on the board I would replace thoses too. Not all old caps are bad caps, but on boards were there are bad ones they usually are all of the same type.
 
Yes old age can do this, as they age some capacitors gain resistance which makes them run hotter and hotter until they just blow. If you had seen the cap beforehand the plastic sleeving on it would probably have shrunk back like heatshrink. Just replace it with a new one, pay careful attention to the polarity of the capacitor, get it the wrong way round and it will do the same thing again - instantly.

Yes the smell is pretty weird, the X2 cap across the mains in my Oscope failed a year or so back and it absolutely stank, on a hot day i can still smell it when the scope is on even after I cleaned up the sticky black tar that it blew everywhere.

If there are other caps of the same rating on the board I would replace thoses too. Not all old caps are bad caps, but on boards were there are bad ones they usually are all of the same type.

Alright... I think I'll pay the $7.50 Bob wants for a whole kit and re-cap the whole board for the hell of it.

Thanks.

EDIT: Thinking on it... when I fired fired up and I heard the "click"...that may very well been a piece of the cap falling to the floor as it was expanding... then when I hit P1 to start it blew.
 
Could also be a power supply issue. Measure the voltage across the points where the cap was soldered in.
 
Could also be a power supply issue. Measure the voltage across the points where the cap was soldered in.

+1 Be absolutely sure your power supply voltages are ok. It usually will do that if something way larger than the rated voltage is experienced. I had a cap like that blow up on me and it smelled like cat urine in my lab for a week.

Bill
 
Be sure and heed Channelmanic's advice - if you've got power supply issues, that would cause blooming on your monitor. I believe I saw a thread of yours earlier today about blooming on a V2000?
 
Be sure and heed Channelmanic's advice - if you've got power supply issues, that would cause blooming on your monitor. I believe I saw a thread of yours earlier today about blooming on a V2000?

I will check it... the "bloom" in question was more a "ZOOM" then stay zoomed than a pulsing action type of "bloom" i've seen in the past.

I suppose I should re-solder in this resistor first.

:D
 
Take things slow. The game is down right now and hopefully it has just warned you about some problem.

To measure the voltages the boardset has to be connected. I looked around and found a post where the resident Omega Race expert talks about it (Omegaman):
http://forums.arcade-museum.com/showpost.php?p=1736182&postcount=72

I haven't done these mods to my power board, so I can't help.

You don't want problems with your game board or it will be pricey to get fixed. I know they sell for a couple hundred working.

I have been an Omega Race Owner for several years now and went overboard rebuilding my game so I'm not much help.
 
Well not SH*T!!

I re-capped... I checked PS voltage before I put the boardset back in... (4.9-4.95v)

I even checked the voltage between the two leads where the last cap exploded... (it measured .5 on my meter with the meter set to 20VDC)... I figured that was OK... but what do I know.

I plug the bastard in. I fire it up...I check the front... the LED's are flashing... good... I wait for the screen to come up... it comes up... all freakin' garbled like it did before... SHIT... right about that time... POP! The new f*cking capacitor blew.

:(

I am really bummin out. I have NO idea how to fix this problem. Any suggestions?

EDIT: I guess I am not at a point where I look to someone out there... anyone work on Omega Race PCB's that want to take a crack at this one (for a fee of course)?
 
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Check the edge connectors again for burnt pins, if they have resistance it could cause issues too, had the same thing happen on a different game as you describe, and the pin was burnt, took out a transistor in mine as well... re pinned connector and replaced cap and it was ok..
 
The ground connector is a little brown but not bad. I am pretty sure I had everything plugged in correctly (about 95% sure I'd guess)... and I really don't want to sacrifice another freakin' CAP... though I guess I could pull the cap off the extra parts board I have here but it's the old style that will explode rather than vent quickly...

I don't have a bunch of 470uf 35v caps... I actually now have NONE other than the old one on the parts board.

:(

I guess it's time to order a few from mouser.

EDIT: Actually thinking on it... this time it did EXACTLY the same thing as last time (crazy ass vectors moving around in the middle upper right of the screen) before it blew... which eliminates a reversed connector because the day prior to it going nuts the first time...it was working PERFECTLY. I turned it off... all was fine... I turned on the game the next day and .... here we are.
 
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Didja check for AC voltage? ;)

That'll blow a cap... and it's what you'll get if a diode is bad.
 
Didja check for AC voltage? ;)

That'll blow a cap... and it's what you'll get if a diode is bad.

That I did not.

...when I check with the meter set for AC at 200v I get a reading of 16.5V.

I am guessing that is bad?


What would it read if it wasn't passing AC through?


How do I determine which diode (if that is the issue) is bad?
 
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