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Buffer chips

nipple

nipple

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Hi guys,

I have a few Naomi’s and a dimm that won’t boot.

From reading on here, all advice points to buffer chips. Seems like this is hit and miss as most things I read, seem to be about 50% success on the swap of the chip. Now I can solder but they are way out of my league to replace.

But, I do see some advice on older jamma games and piggybacking a chip on top of a faulty one as a quick test.

I haven’t seen anyone suggest this with a buffer, but wanted to see if anyone thinks this idea has merit as a quick test before trying to find someone to swap chips and then to find they are not actually the fault.

I thought having a sacrificial buffer that has the legs bent down so it made good connection and then bluetak or hot glue to hold in position for the test.

Cheers
 
Aside from whether it would function or not, I don't think physically it would be reliable enough just with hotsnot or bluetak to ensure every leg has good contact to its peer. If you're going to sacrifice the buffer chip anyway, just solder it on with bent legs.

However, whether it works or not largely depends on the failure mode of the bad chip. If it ceases to function entirely then piggybacking could work, but if the bad chip has an output stuck high or low, it's going to fight with the good chip when it's trying to drive the signal in the opposite direction.
 
IMHO, you should use a logic probe to prove the outputs on the buffer chips. A logic probe isn't very expensive, and that's a more reliable way to test the buffers are functioning than piggybacking.
 
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