F#&*ing EEPROM again???

Magnus Danielson cfmd at swipnet.se
Wed Mar 22 00:43:07 CET 2000

From: "Batz Goodfortune" <batzman at all-electric.com>
Subject: F#&*ing EEPROM again???
Date: Tue, 21 Mar 2000 13:44:21 +0900

> Y-ellow Y'all.
> 	I'm desperately out in the wilderness here. This problem beats the hell
> out o' me.
> The whole system began to fail 2 days ago. Yesterday it just refused to
> boot up. Or at least it refused to get past it's initial LED test.
> Thinking that the problem was something to do with the front panel, or even
> the PSU which is still blowing close to the wind, I pulled the whole thing
> apart.
> To cut a long story short, after removing and replacing most of the chips
> in the system, I removed the EEPROM on a whim. Low and behold the thing
> booted. The EEPROM has absolutely nothing to do with the displays or the
> rest of the system. It's an I2C EEPROM 24C02 and has only a 2 wire
> connection to the micro.
> It would appear that as soon as the micro accesses the EEPROM for the first
> time, the whole system falls over. Now it has to be said that the whole
> system was working just peachy keen for about a month. Then, on the very
> day I decide I'm actually going to use it, it stuffs up completely.
> Now! I've tried replacing the EEPROM with a new one and there is no change.
> I've changed the micro and there is no change. I've tried putting pull-ups
> on it and checked for voltages and all that. I can't detect anything out of
> the ordinary other than there seems to be no signals passing across the I2C
> bus. But this would be expected if the system had fallen in a heap. I
> thought there might be spikes or HV leakage with a bad chip and all kinds
> of other things but I can't peg it.
> I can't think what else to try? It's only 2 wires. I've changed chips. It
> was working perfectly up until 2 days ago. And as far as I can tell,
> there's been no other change what so ever. I certainly haven't changed any
> software or hardware in that time.
> Any clues  would be gratefully appreciated.

Now, if you have had an ESD type of accident, you could go about and apply
some V/I diagram analysis. This is a way to detect burned up inputs and

I trust you have allready check for shorts.


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