24 Jul
2004
24 Jul
'04
12:23 a.m.
>> >>Another one - EPROMs that have been
installed in the
>> socket backwards in a device that posesses a very big PSU tend to glow
>> white-hot then die.
>>
>> But not always! I did this once, saw the bright glow and
>> resignedly went to burn a new EPROM. Just for laughs, I
>> later tried to erase the "burnt-out" part and to my
>> surprise it was still functional and subsequently served
>> the project well. I should have noted the manufacturer ;-)
During the mid-1980's I worked on a large number of projects that used
2716,2732,2674,27128 EPROMS. As A result, I plugged a number of them in
backwards over the years.
The ones most likely to glow were the 2732's. My initial experience was that
if you managed to power down before the circuit burned out, then the device
would erase and continue to work.
After some experimentation with this, a co-worker how had access to our Sem
[scanning electronic microscope] de-lidded one of the working units that had
glowed. Although the unit was still functional visible damage was easily
detected. It bacame company policy that any EPROM that was plugged in
backwards and powered up, had to be immediately scrapped [break off some
pins!] regardless of any obvious damage.
David.