How to program EPROM M2732 21V with TL866? SOLVED  - Page 1
Forum section: electronics / repair

author: Ordinaryman1971
author_rank: Frequent Contributor
timestamp: April 08, 2019, 02:08:15 am
content: I'm trying to program firmware for Keithley 195, one of the eproms is M2732 with programming voltage of 21V. I've read the eprom from a different meter without any problems but I have problem with coping it over.And no, it's not bad eprom, I have about 20 of them, different makers but the TL866 goes up only to 18V.What am I doing wrong here...

author: wictor
author_rank: Regular Contributor
timestamp: April 08, 2019, 04:24:00 am
content: Hi,Is that 18V measured during programming or is from some datasheet? TL866 is powered from USB port, so make sure you are using port that can deliver enough power. I have noticed that most PC ports fail doing that.Wictor

author: wictor
author_rank: Regular Contributor
timestamp: April 08, 2019, 04:28:19 am
content: Is yours TL866 old model or new plus model? The new one only goes to 18V and old one supports 21V.

author: coromonadalix
author_rank: Super Contributor
timestamp: April 08, 2019, 10:22:51 am
content: +1 i dont understand why they changed that voltage ... in the newest version.

author: mc6800
author_rank: Contributor
timestamp: April 08, 2019, 11:05:41 am
content: I managed to program a 27C64 @18V with the TL866II (the datasheet says needs 21V), but only if I increased the duration to 1ms, from the default 100us. The same trick might work for the 2732.The other option would be some sort of extra circuit to feed 21V to the Vpp pin of the 2732 once the TL866 voltage rose above say 15V.

author: tsman
author_rank: Frequent Contributor
timestamp: April 08, 2019, 11:15:19 am
content: Quote from: mc6800 on April 08, 2019, 11:05:41 amI'd be concerned about long term reliability with that trick. It may be okay immediately after programming but you may get early bit rot.Buying some 27C32s which only need 12.5V Vpp is the easiest option IMO.

author: Ordinaryman1971
author_rank: Frequent Contributor
timestamp: April 08, 2019, 02:21:59 pm
content: I went to the maker website and it's correct, new model goes up only to 18V, I have only old version of those EPROMS so all I have are 21V.Anybody wants to sell old version of the programmer... so I could have second one for this sole purpose, lol...

author: wictor
author_rank: Regular Contributor
timestamp: April 08, 2019, 02:25:36 pm
content: How about this:https://www.eevblog.com/forum/blog/eevblog-411-minipro-tl866-universal-programmer-review/650/

author: Ordinaryman1971
author_rank: Frequent Contributor
timestamp: April 08, 2019, 07:16:15 pm
content: I have new version of this programmer, the review is about the old version... which I'm willing to buy if there is anybody willing to sell, there is a voltage difference between those two, the old version will program up to 21V, the new version is limited to 18V.So, basically I'm out of luck.I have an older Willem programmer that I need to dig out and find a software for so I could maybe have it done this way...

author: wictor
author_rank: Regular Contributor
timestamp: April 08, 2019, 08:17:12 pm
content: My post was about the message #650 which shows how to use external voltage to rise max programming voltage. It is not programmer specific.

author: fzabkar
author_rank: Super Contributor
timestamp: April 09, 2019, 07:11:37 am
content: 21V = 18V + 3V lithium coil cell (or 2 x 1.5V alkaline cells)