Frogger capacitor Exploded

thebman80

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Ok, so I have a Sega Frogger PCB and I wire up a test harness for it to JAMMA. Get the pinouts off the web (Mikesarcade.com) and hit the power switch and the 6.8 uf 16v dipped cap near connector 6P catches fire. Now I Disconnect the 12V and board powers up and works fine. The pinouts say the 12v is parts side pin 1 is this to power sound? Or maybe the coin counters? Because All I can say is that this is not the correct voltage for that pin. I had another frog (Frogger boot) PCB and plugged the harness on that and it worked as well the 12v wire was removed and got no fire.

So what the hell incorrect pinout? Everything else worked as far as video and all the 5v and GND hookups. This would be the 2nd time this has happened to me Burgertime pinouts have also been wrong.

http://www.mikesarcade.com/cgi-bin/spies.cgi?action=url&type=pinout&page=Frogger.txt
 
Yes, 12VDC is for audio. That pinout looks correct.....I'd have to check my harness in the shop to be 100%. I have had those tantalum caps in the audio section on Frogger boards blow for no apparent reason.

Edward
 
+1 on exploding tantalum caps. It happens from time to time on old gear.

Double check the wiring then replace the cap and try again.
 
Yeah I have to get some more it just seemed weird to me that this would happen. Would it be bad if I uped it to a 25v cap instead of a 16v?
 
Yeah I have to get some more it just seemed weird to me that this would happen. Would it be bad if I uped it to a 25v cap instead of a 16v?

Yes you can use the 25V in place of the 16V. The key is, you can always use a higher VOLTAGE rating, but you can never use a higher uF rating for caps. The uF's must be the same!
 
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Tantalums like to explode or flame out when they fail. They were still perfecting them back then. Watch your polarity when you replace it. Connect one backwards and you will see it go up in flames like a match. Replacing it with a higher working voltage one may not be a bad idea.

Bill
 
You can replace them with higher uf rating but it may change how the circuit operates.

For example: If it's just a filter smoothing cap you can replace it with a larger uf one just fine. A rule of thumb is -30/+20% change is generally OK.

BUT... if it's a cap in an audio circuit that isn't used for filtering power but instead is in the audio path then you risk changing the circuit to the point of changing the pitch of the audio, allowing noise through that was being filtered, etc.
 
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