On Friday, January 8, 2016 at 12:32:43 AM UTC-5, 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.

I am not familiar with the machines you are repairing, but I might be
able to help you have your questions better understood.

EPROMs are erasable programmable read only memory. They are erased by
shining UV light in that little window. The cover keeps stray UV
light out - NOT "cosmic rays and ****". One thing to keep in mind is
you MUST erase them before reprogramming them. Later parts were
EEPROMS. EE stands for Electrically Erasable. Those don't have the
little windows. You don't Flash PROMS, EPROMS, or EEPROMS. You
program them.

Modern technology uses none of the above. Instead, a completely
different technology called flash is used. So, when you flash
something, you are updating the flash memory in the device - not an
EPROM.

Best of luck with your repairs.