Programming Vintage EPROMs With The TL866II Plus - Page 1
Forum section: electronics / general

author: TheEPROM9
author_rank: Frequent Contributor
timestamp: April 27, 2019, 01:17:33 pm
content: Yes this is posible, heres how. All you need is a 30V varible bench power supply.http://youtu.be/F9ADB7ImSwc

author: ebastler
author_rank: Super Contributor
timestamp: April 27, 2019, 06:23:24 pm
content: Neat!Quick clarification question: Is the EPROM's Vpp pin still connected to the TL866 socket (i.e. does the TL866 tolerate your feeding the 25V into it)? Or do you have to lift that pin, or use an intermediate socket which has that pin lifted or clipped?

author: stj
author_rank: Super Contributor
timestamp: April 27, 2019, 10:12:57 pm
content: i would think the programmer still has control of it to switch it on and off.

author: ebastler
author_rank: Super Contributor
timestamp: April 28, 2019, 07:33:01 am
content: Quote from: stj on April 27, 2019, 10:12:57 pmYes, that's what Iwouldhave thought as well. But the setup shown in the video clearly does not allow the TL866 to control the voltage; it goes directly to the EPROM pin.Let's wait for TheEPROM9, who figured this out, to comment. And maybe explain why this works at all, and does not annoy the hell out of (a) the EPROM and (b) the programmer.

author: stj
author_rank: Super Contributor
timestamp: April 28, 2019, 09:21:34 am
content: i'm surprised that's all he moded btw,those old 21v and 25v eproms needed a lot of current - a lot of cheaper programmers fail because of that - not the vpp levels.it's better to get an old industrial programmer like a Dataman, Stag, Elan etc. from ebay or replace the eproms with 27c16's if you can find some.

author: TheEPROM9
author_rank: Frequent Contributor
timestamp: April 28, 2019, 09:48:08 am
content: No I bent the pin out from the programmer. so the 25V is only roots though the chip, for which it is designed. I guess if it is fulty it could fry your programmer, so test on a disposable one first (I have a dead one somewhere). Always lookup the datasheet of the EPROM, they like to move the VPP around. In regards to why the 25V is litraly just between the VPP pin & the GND pin, so there would have to be internal shorts for it to find another way though the chip.I supose you could add some relay control or something simular so the programmer could root the 25V to the EPROM. Just disable the pin detect or it will error on you. Otherwise the 25V into the EPROM is user controled =-)

author: TheEPROM9
author_rank: Frequent Contributor
timestamp: April 28, 2019, 09:54:25 am
content: Quote from: stj on April 28, 2019, 09:21:34 amThe trobble is with those old EPROM programmers & why I eventaly gave up even trying to get one is.1. They always without fail go for stupid money2. If they are not self contained, they connect to a computer systemthat it is one that is so old that getting your .BIN files on there is a pian in the ass3. Parralle port only (That is its own can of worms)4. Kind of massive & take up a lot of space, I don't have enougth space these days

author: ebastler
author_rank: Super Contributor
timestamp: April 28, 2019, 10:17:09 am
content: Quote from: TheEPROM9 on April 28, 2019, 09:48:08 amAh, OK -- thanks for clarifying. Maybe you should state that clearly in the video, lest people fry their programmer.

author: TheEPROM9
author_rank: Frequent Contributor
timestamp: April 28, 2019, 03:36:09 pm
content: Quote from: ebastler on April 28, 2019, 10:17:09 amNo probs & that is why it is stupid YouTube removed anotations.