help with erasing eprom

[seanlivingstone]

hey guys I am doing a 304 out of a vs conversion into a hq my problem is with the memcal. waiting on an nvram but auspost are taking forever and I'm inpatient so decided to get an eraser and programmer now Is where the problem starts. have tried erasing the memcal a few time but when put in the programmer I get a blank check failed "Device blank check failed at address: 0x000000, Read= 0x3B. Blank check failed" I have read the bin off the eprom and just have a heap of 3f. what am I doing wrong or is the eprom failed? cheers in advance or if you are in the western/northern suburbs of Melbourne and have another memcal that I can buy let me know

current read from the memcal

eprom.bin

(128 KiB) Downloaded 246 times

[Ken]

The intensity of the UV light you're using will determine how long it takes to erase.
I have a small compact eraser that takes roughly 30-40 minutes to erase some chips 100%, and a full size eraser that'll do 16 chips in 15-17 minutes, has a larger UV lamp bulb in it.
"ff" is what the data in the chip ends up with when it's fully erased, your code looks like it's half way there, just needs longer in the light I suspect.

[immortality]

How long are you putting the eprom under the uv eraser light? You also need to make sure the window is nice and clean.

[seanlivingstone]

have had it in for 45 mins at one point. put it back in half an hour ago and havent checked it again. i guess ill leave it for a bit longer and see what reading i end up with. thanks heaps guys

[delcowizzid]

If its a cheap grey chinese eraser max 5-7 minutes or you will make the chip real slow to respond.make sure the window is clean and aim it at the tube.i don't blank check just hit program cause my old willem programmer used to write the first byte when blank checking and programming would fail.erased should be all FF. Did you unsolder the eprom or using a programming header heat can kill the chips

[seanlivingstone]

just left it in again and cleaned the window looks like it may be getting somewhere but is taking forever. will try not do a check next one but if after 5-7mins it runs slow ive probably cooked mine... this Is where I'm at currently. also just using a memcal adapter

Device blank check failed at address: 0x000003, Read= 0xBF.
Blank check failed

11.bin

(128 KiB) Downloaded 232 times

[Ken]

Length of time erased might be a problem, or the programmer you're using, I've just come to realize my older GQ4x with the early firmware version is a nugget.

Code: Select all

Just how long it takes to erase an EPROM will depend on the light intensity and the EPROM itself. Typically, my eraser will blank a chip in about 20 minutes. Be careful as EPROMS can be damaged from too much exposure. Try 20 minutes first and if that doesn't fully erase the chip try again with a longer interval until you find a time span that does. Most EPROM programmers allow you to check if an EPROM is blank (see below).

Source:

[seanlivingstone]

yeah ken thinking it may be damaged. tried 10 mins first and that didnt work so went another 45 and yeah think i may have fried it.

[Ken]

Yeah you might have overdone it, the little unit I was referring to in my first post was originally a battery powered tooth brush sanitizer, in a silicon chip magazine years ago they showed how to add a capacitor inside of a particular model to make it stay on longer that it originally did, in order to erase chips.

Where abouts are you located, maybe I or someone else here could either send you a chip or swap yours out for you.

[seanlivingstone]

hey mate im in diggers rest so west melbourne but will happily drive most places in vic tonight to get this nugget running in the morning