F#&*ing EEPROM again???

Batz Goodfortune batzman at all-electric.com
Tue Mar 21 05:44:21 CET 2000


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.

Be absolutely Icebox.

 _ __        _                              
| "_ \      | |         batzman at all-electric.com
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