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mike[_22_] mike[_22_] is offline
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Default Seeking Opinon on EPROM Problems

On 1/7/2016 9:32 PM, wrote:
I have a bunch of the same units now that I kinda work for factory service. These are Karaoke machines which are modified CD/DVD players.

I get like three different symptoms on certain models. OK there was a fourth that was even weirder but that was only one out of a bunch. Also, out of a bag of EPROMs they have the same symptoms. We got alot of parts that are used and that is something totally else to deal with.

Anyway, when you find there are only three major symptom sets that follow these EPROMs around (I spent the better part of a day switching them to numerous mainboards)Would you think the EPROMs went defective or they got hit with a software error, like having the plug pulled at the wrong time ? These things DO have mechanical power switches.

But then this is a Chinese manufacturer and they might have gotten a batch of them really cheap and they ARE the problem.

To exacerbate this dilemma, these things are shipped in worldwide. Shipping costs money. But if I order a ****load of ICs and the same thing happens that is worse.

If it is a software thing, I got the EPROM copier and if it is likely to be software I need zero parts. Just put in a chip with a the good data and bam it is done. How long it lasts depends on alot of things, cosmic rays n ****. (I **** you not, there are articles on that, in fact should I put a foil tape on top ?)

And what if I get cheap EPROMs and they go bad ?

Well, that's the question. Start flashing the chips I got or get new ones ? Note that we also got rush jobs. Not really rush but they have been there long enough.

One symptom that EPROMS can exhibit is speed related.
You can test them all day in an EPROM programmer, but they still won't
work in the product. This was a problem in some early Compaq 386 laptops.
And some TEK instruments.
Reading the device in the programmer, then writing it back fixed 'em.
The laptop ones failed again eventually. As I recall, the designers
let some of the control lines on the prom float. I guess that allowed
some electrons thru to contaminate the bits. New chips soon exhibited
the same symptom.