Nov 082017
 

Received this quite rare Hard Puncher (on Konami Twin16 hardware) for repair:

PCB failed all the time the self-test showing a bad device @10G on CPU board and then resetted, this in an endless loop:

The involved device is a Mitsubishi M5M5165 (8K x 8-bit static RAM) compatible with 6264 :

Its data bus showed no activity:

The chip failed the out-of-circuit test each time in a different address location:

With a good RAM the board successfully booted into game:

But speeches were missing, here is a comparison with a MAME recording:

I quickly pinpointed this fault in a missing 640KHz ceramic resonator, this is for generating clock to the uPD7759 ADPCM speech synthesizer IC.I took a spare from a dead Sega System16B motherboard:

Job done.

 Posted by at 9:13 am

  One Response to “Hard Puncher repair log”

  1. Ah ah, this damn 640kHz cristal.
    It sticks out a little bit too much of the top board and get ripped so easily.
    The last 3 Twin 16 boards I fixed had it missing!
    See my last Devil World repair.

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