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Silkworm Repair

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matman:
Have an original silkworm that had LEDs on, but no video.


Z80 CPU Reset was stuck low and traced back to a 74HC04 at 1C that was not sending anything out on pin 12.
Piggy backed the chip and now have static blue on screen.


From what I can tell now, the RESET is still stuck low because VBLANK is stuck HIGH.
Believe this originates from the MN50005XTA custom chip pin 26.  Almost the whole right side (pin 17-28) are stuck high, but the left half of the chip seems to be operating fine.


Think some bootlegs replace this, but I'm not sure of the breakdown of those daughterboards.  Was hoping to create my own if need be.


Additionally, it seems that per the Rygar specs which is a close hardware setup, the path for VBLANK goes through the MA7053, but on the Silkworm it is as if the 7053 and the 50005xta are swapped compared to Rygar, which makes me wonder if they are basically the same 28 pin setup but in different package (but i'm not sure).


Any thoughts/help appreciated.


Thanks!
Matt

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