Space Bomber graphic glitch

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yojo!
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Space Bomber graphic glitch

Post by yojo! »

I'm running into a weird issue, see for yourself:

Image

I already tried cleaning the connector edge and the issue still remains. The glitch is not specific to some graphics ; it appears randomely. For example when I leave the game in demo mode the piggy on the above picture is OK during many demo cycles and every once in a while appears corrupted as shown above.

This leave me to believe that the "ROM" part is OK and another component is in fault. Anybody has any clue what I could do ?
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mastercello
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Post by mastercello »

Have you checked +5V and +12V with a multimeter?
yojo!
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Post by yojo! »

mastercello wrote:Have you checked +5V and +12V with a multimeter?
Yep both are in range. I tried on 2 cabs and a supergun and the issue is the same...
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robivy64
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Post by robivy64 »

Those boards use mostly surface-mounted components, which are more prone to cold solder connections.

One of the ROMs most likely needs to be resoldered or reflowed.
yojo!
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Post by yojo! »

robivy64 wrote:Those boards use mostly surface-mounted components, which are more prone to cold solder connections.

One of the ROMs most likely needs to be resoldered or reflowed.
But if it was a rom then wouldn't the sprite be always be corrupted ? Like on the picture above the pig is ok accross multiple Demo mode cycle and is messed up for a brief period of time during one demo mode. Same story goes for other sprites or the tittle screen as well.
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robivy64
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Post by robivy64 »

Nope, not always.
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Dave_K.
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Post by Dave_K. »

I agree with Rob, it looks to like the board has been flexed, and some of the legs on the surface mount chips are coming off their pads. Probably the large Psikyo GPU chip is the problem. Did you recently get this board, and was not packed securely? Do you handle your boards roughly when you plug the harness on them?

If you can get it to consistantly glitch at a certain point, with the PCB sitting flat on some cardboard (no pcb feet), then try pressing down on the GPU to see if it goes away. This test will show you which chip(s) need to be reflowed.
yojo!
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Post by yojo! »

I got it from Ebay 6 months ago. I handle my PCB with extreme care. I keep them in anti-static bags and store them vertically in individual boxes. I''ll try what you guys are suggesting. Thanks for the help.
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robivy64
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Post by robivy64 »

Better to store horizontally, as the weight of the board is evenly distributed since it is lying flat.
yojo!
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Post by yojo! »

You guys are right; when i press on the green spot on the chip at the bottom right of the picture then the problem disapears. I don't have to keep on pressing for the game to be fine.

However if I gently press on other part of the board then the problem re-appears again. I took a close look at the IC'pins and they seems to be soldered properly onto the board.

Image
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robivy64
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Post by robivy64 »

You aren't going to see a hairline fracture in the solder with the naked eye. That should be very simple to repair, just reflow the solder on each of the pins on that ROM.
yojo!
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Post by yojo! »

robivy64 wrote:You aren't going to see a hairline fracture in the solder with the naked eye. That should be very simple to repair, just reflow the solder on each of the pins on that ROM.
Thanks for the info;from looking at wiki it seems that it requires some specific hardware; do you know a place I could send my PCB to to get it done ?
yojo!
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Post by yojo! »

update:

I just had the PCB's chip re-flown and it seems to have fix the problem :D

I will leave the game in demo mode for a week to make sure it is completely fixed.

Thanks everyone !
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Dave_K.
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Post by Dave_K. »

Cool, glad you got that sorted!

Did you have just that one chip you identified reflowed? Also did you find a service to do this, or a friend with an SMT station?
yojo!
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Post by yojo! »

Dave_K. wrote:Cool, glad you got that sorted!

Did you have just that one chip you identified reflowed? Also did you find a service to do this, or a friend with an SMT station?
We have the equipment at work to flow PCBs; a friend of mine re-did the chip only; not the entire board. Now it's in free play in our break room :)
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