cbmeeks Posted April 22, 2021 Share Posted April 22, 2021 I have a MiniPro TL866CS that I've had for years. I've noticed today that all of my EEPROMS won't program 95% of the time. They read just fine. I have some 28C256's and some 28C64's. I've tried about 10 different ones and all seem to read OK. But only one 28C256 will program OK and it only does it about 1 out of 20 times. I even decided to fill the chips with a specific number (42) and it fails. BTW, it SAYS it programs just fine. But all validations fail. Even the all "42"'s fail. When I fill it with 42 and read back, it has a different number like 53. So, do you think it's time for a new programmer or is there something maybe I can check? Thanks for any tips. Quote Link to comment Share on other sites More sharing options...
+DrVenkman Posted April 22, 2021 Share Posted April 22, 2021 How old are your EEPROMs and are you sure they're legit (not counterfeits or fakes)? Do you have any new, known-good chips you could test with? It's also possible that your programmer has an internal fault and isn't producing the correct Vpp. You could rig up a little jumper wire and hook it to a multimeter to verify the programming voltage when you try to write to a chip. Quote Link to comment Share on other sites More sharing options...
+5-11under Posted April 22, 2021 Share Posted April 22, 2021 I've had at least one die on me... maybe two... can't remember. Maybe it was the Vpp?... some chips still worked okay 1 Quote Link to comment Share on other sites More sharing options...
cbmeeks Posted April 23, 2021 Author Share Posted April 23, 2021 13 hours ago, DrVenkman said: How old are your EEPROMs and are you sure they're legit (not counterfeits or fakes)? Do you have any new, known-good chips you could test with? It's also possible that your programmer has an internal fault and isn't producing the correct Vpp. You could rig up a little jumper wire and hook it to a multimeter to verify the programming voltage when you try to write to a chip. Well, the 28C64B's are several years old. They are legit because I got them as free samples directly from Atmel. My 28C256's are also legit (and within 2-3 years old) as I bought them from Mouser. I rarely purchase chips from eBay/AliExpress unless it's something like a VDP or GAL (even still, I try to use the same eBay seller). Funny thing...damn thing started working again. I did flash the firmware to the newest version. So fingers crossed this will continue to work. When things work, then don't work, then work again...well, that makes me nervous. I may try the multimeter test as well. Thanks everyone for the help. Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted May 12, 2021 Share Posted May 12, 2021 I have one that has been a bit flaky lately too--but the problem is somewhat readily identifiable. The USB connector on the board is starting to loosen up. When the cable sits just right, all is good, and when not, it won't program most of the time. I need to open it up and reflow the solder there. . . Quote Link to comment Share on other sites More sharing options...
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