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'Over Voltage on 16C71JW'
1998\10\28@033845 by Steve Parker

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          Hi folks,
               Unfortunately I accidently powered my 16C71JW with >10V
  and after an erase, the programmer says it can't reset the code protect -
  I've tried erasing it for 1 hour and still the same result. Should I
  throw it in the bin or is there anything I can do to resurect it?
                  Yours in mourning,
                            Steve Parker.

1998\10\28@053643 by brad

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Steve Parker wrote:
>
>            Hi folks,
>                 Unfortunately I accidently powered my 16C71JW with >10V
>    and after an erase, the programmer says it can't reset the code protect -
>    I've tried erasing it for 1 hour and still the same result. Should I
>    throw it in the bin or is there anything I can do to resurect it?
>                    Yours in mourning,
>                              Steve Parker.
This is probably not what you want to hear. But I used to do that by
mistake with plain
Eproms from time to time. It's the best way I have found to turn an
Eprom into a Rom :p)
After a blast of overvoaltage, they rarley ever erased again. They did
hold thier program
and function properly though.

Rgds.
Brad Campbell

1998\10\28@130205 by Peter L. Peres

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On Wed, 28 Oct 1998, Steve Parker wrote:

>            Hi folks,
>                 Unfortunately I accidently powered my 16C71JW with >10V
>    and after an erase, the programmer says it can't reset the code protect -
>    I've tried erasing it for 1 hour and still the same result. Should I
>    throw it in the bin or is there anything I can do to resurect it?
>                    Yours in mourning,
>                              Steve Parker.

What does the programmer dump if you try to read out the chip ? Do you get
0x000, 0xFFF, or jumble. If you get jumble there may be a fair chance, so
try some more imho.

Peter

1998\10\28@150859 by Craig Lee

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I have a couple 16C62AJW chips that have such a problem, but they just
seemed to go one day.  Perhaps ESD.....

Certain banks have gone bad it seems.  So I know how your feeling Steve,
there....... there......

Is there any drastic measures we can go to to solve these issues?

>From other posts in the past, is it more likely for 16C62AJWs to fail?

Craig

{Original Message removed}

1998\10\29@132125 by Peter L. Peres

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On Wed, 28 Oct 1998, Craig Lee wrote:

> I have a couple 16C62AJW chips that have such a problem, but they just
> seemed to go one day.  Perhaps ESD.....
>
> Certain banks have gone bad it seems.  So I know how your feeling Steve,
> there....... there......
>
> Is there any drastic measures we can go to to solve these issues?
>

The only 'reviving' methods known to me rely on physical means to try to
remove charge 'injected' into the bulk or insulation layers of the chip
during the ESD or HV exposure event. I have seen CMOS chips gone bad like
this come to life after passing through the reflow process, and that's
where I got the 2nd idea. So I advocate and use the following 2 methods:

1) Leave the chips in the EPROM eraser as long as a week (in a production
facility the eraser runs all the time).

or

2) Place the chip in a normal cooking oven at 150 degrees or so overnight
(8 to 10 hours).

In both cases all the pins are to be shorted together, for UV with static
foam or aluminium foil, and for the oven with a thin soldered wire or a
socket with shorted pins. Pick an epoxy base socket.

This has worked for me in the past a few times, but I don't claim that it
does for you, and use it at your own risk, knowing that you may destroy
the chips completely by doing this.

Peter

PS: As to success rate, as a rule of thumb, I can say that if the chip
failed in an environment where there was no major increase in current draw
of the chip during the fault ('just went dead') the chances are slightly
better.


'Over Voltage on 16C71JW'
1998\11\05@095251 by Nigel Orr
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At 08:35 28/10/98 GMT, you wrote:
>                Unfortunately I accidently powered my 16C71JW with >10V
>   and after an erase, the programmer says it can't reset the code protect -

Just the code protect?  Did you set the code protect?  If so, then you
can't erase it, at least not easily, whether you overvoltaged it or not-
I'm still trying to clear 3 16c620/JW's from where I learnt this the pricey
way...

Nigel

--
Nigel Orr                  Research Associate   O   ______
       Underwater Acoustics Group,              o / o    \_/(
Dept of Electrical and Electronic Engineering     (_   <   _ (
    University of Newcastle Upon Tyne             \______/ \(

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