Problem burning Texas Instrument eproms.

[bust3dstr8]

I pulled about 20 TMS27C040 from a parts board and they all erased fine.
The problem is they all program about dozen or so bytes and then fail.

The TI datsheet says VPP 13V and pulse 100µs, that's what my programmer
defaults to when I select the chip.


Is it possible that all the chips are just tired or more likely that the programmer
isn't configured properly to write these?

[FABombjoy]

It's possible that they've been either erased or programmed to death.

http://wiki.xtronics.com/index.php/How_EPROMS_Work#OK.2C_So_tell_me.2C_just_how_does_ an_EPROM_work.3F

I've encountered both before and the result is what you're seeing. Burner gets a few steps in and gives up.

[bust3dstr8]

Thanks.....I have never run into ones that don't program, just ones that won't erase.

I'll give them one last try and start trashing them if they fail.

[Bratwurst]

I'd look at the programmer itself as a potential culprit too. To fail on 20 identically manufactured ICs...

I've had a programmer, an old one, granted, refuse to program a certain type of chip before it gave up the ghost completely. Possible that the power supply for the programmer's giving out?

[bust3dstr8]

I program other chips at 12.75Vpp to 13.5Vpp without fail.

Anyone want a couple to try on a programmer other than a Wellon-490?




/Edit: I did try them as other chips with the same settings...NEC and Intel.
Same result, a few bytes programed and then fail.

[FABombjoy]

Yeah, now it's sounding like a burner problem. Open it up, might be obvious. Last time I had a burner problem one of the transistors in the charge pump had burst.

To add to the realm of programmed-to-death, every EPROM I've removed from a Jag CD could not be re-programmed, at least with the equipment that I have.