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Mikie PCB Help


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I've always thought a picture tells a thousand words?

 

How come you can't see it?

 

The PCB shows weird lines that look to be constantly scrolling up and down. So looks like there's a sync problem (amongst probably other problems with the board).

 

I can coin the game up and hear the sounds of the game playing

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How come you can't see it?

 

Because I am in China and Youtube is blocked here along with Facebook, most of Google and numerous other sites.

 

Sounds like possibly an earth to the monitor type of problem? Maybe try connecting the monitor earth (the one bundled with the RGBS) to the correct earth specifically for the monitor on the edge connector?

 

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How come you can't see it?

 

Because I am in China and Youtube is blocked here along with Facebook, most of Google and numerous other sites.

 

Sounds like possibly an earth to the monitor type of problem? Maybe try connecting the monitor earth (the one bundled with the RGBS) to the correct earth specifically for the monitor on the edge connector?

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Hi, this is a test setup so is fine with other Konami boards, using the same adaptor. The problem is with the PCB somewhere. I will try and put the video somewhere else where you can see it. Cheers!
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Defo a PCB fault, as you can hear the game running and you can coin up and hear it playing it rules out a lot of the board, but you have a fault in the video generation section, almost certainly bad Fujitsu TTLs.
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There is a board diagram available online for this PCB

 

Thanks I have the schematics. I've looked around the sync area with my logic probe - so the LS244 @ 13G, the LS241 @ H16, and LS273 @ F15. Not found anything yet. Any specific areas you think I should look at would be helpful

 

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As I said on UKVAC forums I think your faulty is located in video timing circuit.Usually ICs involved in this part of circuit are counters 74LS161/163 so I'd check them for first.
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  • 4 weeks later...
You will struggle to check a counter with a logic probe, especially if its a Fujitsu chip and suffering from a lost input pin internally. The outputs can still be firing but they are firing in an incorrect pattern as the circuit inside the chip is only seem some of the inputs you can see on the external leg. Your only option for those is to use a logic comparator, desolder them and test them in a modern EPROM burner, or just replace them if they are Fujitsus.
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  • 1 month later...

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