SNES black screen after a while

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philenotfound
Posts: 11
Joined: Sun Oct 16, 2016 1:03 pm

SNES black screen after a while

Post by philenotfound »

Hi,
I bought a SHVC-CPU-01 board, it works fine, at least for a few minutes, sometimes hours. Then suddenly i see the screen glitching out and it goes black. Sound continues playing. Reset doesn't bring it up again. Powering it off, leaving it off for a few moments, sometimes minutes, and it is able to boot up again.
7085 seems to output 5V according to DMM.
Reset button seems to work fine if the console runs normally, eg before crashing/blackening out.

So far I tried:
* changing the audio module (didn't expect that to be the culprit, was it was easy and fast): no change.
* changing the cart slot: at first it ran for hours, but today it blacked out again, so that wasn't the problem.

Next suspects are the capacitors, but I'll have to wait for it a little longer since the seller may resend a board, so I won't be doing any soldering on the board before that has been sorted out.

Anyone experienced similar behaviour or has any tips for repairing?
Kismet
Posts: 60
Joined: Wed Nov 30, 2016 9:59 pm

Re: SNES black screen after a while

Post by Kismet »

philenotfound wrote:Hi,
I bought a SHVC-CPU-01 board, it works fine, at least for a few minutes, sometimes hours. Then suddenly i see the screen glitching out and it goes black. Sound continues playing. Reset doesn't bring it up again. Powering it off, leaving it off for a few moments, sometimes minutes, and it is able to boot up again.
7085 seems to output 5V according to DMM.
Reset button seems to work fine if the console runs normally, eg before crashing/blackening out.

So far I tried:
* changing the audio module (didn't expect that to be the culprit, was it was easy and fast): no change.
* changing the cart slot: at first it ran for hours, but today it blacked out again, so that wasn't the problem.

Next suspects are the capacitors, but I'll have to wait for it a little longer since the seller may resend a board, so I won't be doing any soldering on the board before that has been sorted out.

Anyone experienced similar behaviour or has any tips for repairing?
I would suggest bad caps. The two complete SHVC units I have are just black screen, and they quit working while in storage (the original one I had also died in storage.) I bought a SFC from Japan that worked for about a week and then it stopped working the next time I powered it on. So I wouldn't rule out bad caps. The only working SNES I have is the GPM-02, and it's just a bit dark, but that might just be the s-video cable.

Any other hardware I would normally suggest something thermal, as that is the trademark of overheating.
I come from the net. Through systems, peoples and cities to this place.
qwertymodo
Posts: 775
Joined: Mon Jul 02, 2012 7:46 am

Re: SNES black screen after a while

Post by qwertymodo »

Agreed, it definitely sounds like overheating, but that's not really an issue with the SNES, so my money is also on the caps.
philenotfound
Posts: 11
Joined: Sun Oct 16, 2016 1:03 pm

Re: SNES black screen after a while

Post by philenotfound »

I started by desoldering C67, C63 and C64 and testing them with a component tester.
C63 came up with only some pF capacitance. I ended up replacing all three with new parts.
So far no black screen anymore, only time will tell if it is really fixed.
philenotfound
Posts: 11
Joined: Sun Oct 16, 2016 1:03 pm

Re: SNES black screen after a while

Post by philenotfound »

Black screen still came after a while. Built a Burn-In Test cartridge. Was able to get a black screen everytime during Burn-In Test.
Turned out it was C62, the one near the CIC causing the blackouts.
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