trying to program an AM27C1024 and getting buffer errors help

[Mike26]

Hey guys I know you all told me at one point or another to never purchase that POS willem programmer and when I didn't listen two years ago I used it and it worked great. I was happy. Last night I decided to crack open my old mega CD and attempt to update the bios to this region free one:

http://www.assemblergames.com/forums/showthread.php?27562-Mega-CD-real-region-free-on-game-discs

I opened my mega cd and the bios was already socketed and an EPROM. Nice I figured and removed it and got my willem PCB50B programmer out that I've used in the past and my external 12v 1amp DC external power adaptor, and read the chip. It checked out with stock bios. Took the chip to my UV eraser for 10 min and checked for "blank check" and it checked out.

I made sure to byteswap the bios before burning. It got about 7 seconds into the write before spitting out a buffer error...

I am unsure what I am doing wrong. I have my 16 bit adapter hooked up, I have the dip settings set like it says for 27C1024 in the program, and I don't know what settings to use for TWP and the other one, but I moved the TWP from 120 to 140 and no difference... Infact the chip is no longer responding.

Is my programmer a complete piece of you know what, or is the problem I am way over my head with erasing and writing to EPROMS, or is it a combination of both?

I hope it's something simple I am doing wrong.

 

[Xian Xi]

Don't AMD chips need 12.75v for programming?

 

[Mike26]

good call on that, problem is my piece of garbage PCB50B willem model even with a 12v dc 1.5amp external powersupply cannot do the trick. I think i need to try a 21v powersupply and jumper the "21v" option. I just cannot be certain this is safe, as something is telling me the 21v jumper is for certain types of ST EEPROM chips that require 21v...

Eitherway, I have nothing to lose I will try and find a 21v proper polarity dc wallwart adaptor to test this.

Thanks X

 

[CafeineCake]

the willem and other programmer CAN generate 12.75 and other voltages from a 12V PSU. At least the MC34063A in it's schematics suggest so.
Putting in a 21V supply will most likely do nothing because the jack basically goes to a small bridge and then an lm7805.

^__ is speculation based on the schematics of a willem programmer i have.

 

[Elgen]

I think it sounds like the EPROM is toasted. Ie if it was programmed with a too high Vpp the first time it was programmed, it's quite normal that it erases fine, but that it is impossible to reprogramme the gorram little frakker.
Try with another one...

 

[The Webmiester]

Just a note on the Willems, I can burn everything just fine except 27c800. Absolutely will not successfully burn one. You may find that there's just some quirk on your board to prevent it from working.

 

[Xian Xi]

Just a note on the Willems, I can burn everything just fine except 27c800. Absolutely will not successfully burn one. You may find that there's just some quirk on your board to prevent it from working.

Double the image and burn it as a 160.