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I googled a heap and get mixed answers.

Want to see what you guys on here like to do

I know all uv erasers different but i have the run of the mill china ones like the ones that are for sale on here.

Erasing vn to vs memcals with the 27c chip how long do you guys leave under the uv light for?

Some people say 7mins is enough others say 20 mins needed.

I got a 27c512 chip here i burned a 12p tune onto couple of months ago now trying to wipe it again (and burn final tune) for a friend.

Ive tried probably 8 times now to wipe it. Under uv light for as low as say 7min and up to 20 min other times

Put it in my ancient willem programmer. Parallel port and usb for power. I load the bin up hit burn and every time it burns to 100% then i get this error.

Error at 0x00000 Chip = oxff buffer = 0x00

Just do a blank chip check before writing & it’ll tell you, some chips I’ve done can take up to 40 minutes(I take it out & check every 10 minutes or so) other chips can erase in 5 minutes!

I've found the later MEMcals need longer. VS I was having to erase under a UV lamp for over 20 minutes or longer on the odd occasion. Where ever possible I try to use a MEMcal with Eeprom now. much more convenient.

I also upgraded to the new burner, my old Willem didn't like the VS style chips at all.

The bits all flip to 1 on erase, so FF is erased, then the zeros are written at program time. So that error looks like your programmer isnt programming. The very first byte at address 00 is erased (chip=FF), but its not writing to 00 (buffer=00) when it should. Check the programmer has got enough power and the right chip type configured. Writing those eproms requires a bit of power sometimes, maybe the parallel port cant supply enough if your relying on that. I recall some of those programmers had parallel (for data), usb (for power), or power style plug for power. Try some different options/cables for power and/or usb power).

Agree about the erase time, and sometimes the angle of the light, Ive had to change the angle of the chip to get all bits to erase, but start with the blank check or a read and look in the buffer and see what comes back, it could be your erase is working fine.

I Havnt done much burning in years but I don't remeber the old vn vp 128 chips being as hard to erase burn as the last 2 vr vs chips I've tried to do.

Willem programmer Burner is old style with parrell port for dat and usb for power by looks of. It also

Thanks for the info guys

The higher the capacity the eprom the longer it takes. The 128k ones would take me about 5 min while the 256k ones were about 17 min.

It's something to do with the cell size, higher capacity are much smaller.

Thanks for the info vlad

The error is most likely a bad pin connection or not enough programming voltage it hasn't programmed the 1st address and its failed the verification. Try choosing a different brand of 27c in the programmer software it will probably work on some brands better than others due to the programming times being different. Those old will ems you sometimes had to slow down the write speed sliders to get them to program

Delcowizzid you referring to the twp and twc to drop them values numbers down a bit more?

Also this what i have my eprom programmer settings on see pic below

Have memcal into moates adaptor into willem programmer as per diagram screen shot.

I tried now another 4 or so times to erase eprom now 10 mins at a time then blank check and it wont even pass the blank check.

Tried of 2 other usb power sources also to power the willem programer. One a genuine 2amp phone charger

Driving me up the roof

Looks like maybe my uv eraser, maybe dying after all these years. Gave the eprom a good 35 min or so hit under it slowed the twp and twc down
and looks like all burnt good
Will give it a go in car this weekend