Date: Thu, 13 Nov 2003 17:07:15 -0800 From: John Niven <[EMAIL PROTECTED]>
On Thursday, November 13, 2003, at 03:54 PM, Jeff Walther wrote:
Identify the power pin on the memory chips. Now, unless the memory chips are 'J' lead, it should be possible (with careful soldering) to lift the power pin of the memory chips one at a time. This will completely disable that chip and by observing the affects you may be able to determine which is the faulty chip.
Not a bad idea Jeff! Except that now the chip has no power, and it's inputs are being driven. The typical ESD input protection circuit may well pull down the address/data bus and prevent any of the memories working properly. Maybe there is a chip select pin that could be disabled instead.
Good point, although I think that the ESD only kicks in at voltages well above the normal operating range. But ESD circuits are not something with which I am strongly acquainted.
Anyway, operating on the Chip Enable or Chip Select pin would work nicely and might be easier. Most of those seem to be active low, so you could probably disable the chip, just by tieing it to 5V.
Hmmmm. That may raise other issues though. Mightn't there be other chips on the same CE_ circuit. One probably still needs to disconnect the pin from the pad (to avoid affecting other chips) and then tie it high.
Or, I think I saw a SM Thunder II on Ebay in the Apple Mac/Video section currently at $2 with no bids...
Jeff Walther
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