Problem erasings EPROMS

Dlsmith

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Just got a EPROM eraser from China. I have several Intel's 2716 that just won't erase completely. I was able to erase some TI's 2516s. Has anyone else every had this problem?

Thanks...
 
Just got a EPROM eraser from China. I have several Intel's 2716 that just won't erase completely. I was able to erase some TI's 2516s. Has anyone else every had this problem?

Thanks...

the windows are clean on the eproms?? How much time are you erasing them for??? China???
 
I have the same problem with older EPROMS. They are probably 35+ years
old and don't last forever :(

JD

Just got a EPROM eraser from China. I have several Intel's 2716 that just won't erase completely. I was able to erase some TI's 2516s. Has anyone else every had this problem?

Thanks...
 
Just got a EPROM eraser from China. I have several Intel's 2716 that just won't erase completely. I was able to erase some TI's 2516s. Has anyone else every had this problem?

Thanks...

Things that might help.

It maybe that weak EPROM eraser from China, a longer time exposed to the uv light might do the trick but understand that too long will shorten the amount of times you can erase an EPROM or permanently damage the EPROM.

Is the window to the EPROM clean and glue residue or bit of label left on the EPROM will block the uv rays and prevent your EPROM from being fully erased.

How are you checking the EPROM is blank? Some USB based EPROM burners just do not work well with older 2716 and 2708 EPROMs. They will still register as not blank when they are.

If your using an USB EPROM programmer are you using an external power supply?

If your using a laptop is the laptop to program EPROMs is the laptop plugged into the wall? Some older USB port go into a power saving mode when the laptop is just running off the battery. This will cause bad burn.

Can you slow down how fast you read an EPROM. Some older EPROMs will give you a bad read if you trying to go too fast..

Good luck with your problem..
 
Those cheap erasers from China are junk. I have one, and have been using it for about 6 months, and have run into all sorts of chips it won't erase, and most chips took several cycles to fully clear. The problem is that it only has one bulb, and it's a weak one. So some chips you need to leave in there for a long time, close to an hour.

I recently ditched it and bought a used Spectroline on ebay. It has two bulbs, so moar power. Haven't had a problem since.
 
You need to have the chip directly under the bulb or portions of the die will be shaded from the light and not erase properly.

Some of the worse are Hitachi 27c4096 that have a die larger than the window. My spectroline erasers will handle them fine but my small since bulb eraser requires erasing twice - once slightly to the left of the bulb and once slightly to the right for the UV light to reach the corners of the die
 
I recently ditched it and bought a used Spectroline on ebay. It has two bulbs, so moar power. Haven't had a problem since.

I also bought one of the ebay chinese erasers. Instead they shipped me a 50 cent plastic bottle. Needless to say - the plastic bottle doesn't erase EPROMs. They wanted me to send bottle back before they would ship out the eraser. No way - would cost $9 to ship. Had to go thru paypal and to get my money back.

Spectrolines work great. Shorly after the chinese water bottle eraser, I found a Spectroline PE240T with a buy it now of something like $20. Like new condition and amazed I found it before anybody else. Quite happy.

Watch ebay for the timer versions of the Spectroline erasers - they do pop up often.
 
I also bought one of the ebay chinese erasers. Instead they shipped me a 50 cent plastic bottle. Needless to say - the plastic bottle doesn't erase EPROMs. They wanted me to send bottle back before they would ship out the eraser. No way - would cost $9 to ship. Had to go thru paypal and to get my money back.


The bottle is for putting all of the junk chips in that their eraser won't erase.

They're just saving on postage and not bothering sending the eraser.
 
If you erase them too long that will also kill them.

I believe that is a popular myth. It's the programming process, the charging of the internal caps, that causes stress on the IC. The chips have a finite life span specified as a number of programming cycles. Minimum erasure times are specified but there's no maximum limit on the UV exposure. I once had a strong UV erasure box that I loaded with more than 20 chips at once and the mechanical timer stuck so it never shut off. I forgot to check it and left it there running for a couple of weeks. All the chips came out blank and programmed afterward just fine. I've been programming and UV erasing all sorts of chips since about 1988 to present and I've never seen an instance of over-erasing causing failure. People just assume that because it won't become blank that it was the UV that caused the problem. It wasn't. It was the last programming cycle.

Bill B.
 
I believe that is a popular myth. It's the programming process, the charging of the internal caps, that causes stress on the IC. The chips have a finite life span specified as a number of programming cycles. Minimum erasure times are specified but there's no maximum limit on the UV exposure. I once had a strong UV erasure box that I loaded with more than 20 chips at once and the mechanical timer stuck so it never shut off. I forgot to check it and left it there running for a couple of weeks. All the chips came out blank and programmed afterward just fine. I've been programming and UV erasing all sorts of chips since about 1988 to present and I've never seen an instance of over-erasing causing failure. People just assume that because it won't become blank that it was the UV that caused the problem. It wasn't. It was the last programming cycle.

Bill B.

Agreed.

Sometimes you can program one with a stuck bit with all zeros then erase it and use it without problems. If it'll erase after doing the all zeros it will program just fine.
 
I find that once i put eproms in the eraser they still won't program correctly i try again if still no go usually go in the bin i would say 9 out of the 10 eproms i got from old scrap have been ok to reuse but some are well as i say had there time
 
Agreed.

Sometimes you can program one with a stuck bit with all zeros then erase it and use it without problems. If it'll erase after doing the all zeros it will program just fine.



Also, know that you can also program ones with stuck bits, as long as the stuck bits are stuck at the same value as the code you're wanting to load on to them.

I've got a few ones with one or two stuck bits each, and will just try those first whenever I need to burn one of that size. If it works on the first try, great. Else, they go back in the eraser, and I'll try again next time. Eventually you'll find code whose bits match the stuck ones, and they'll work. (I also label the ROMs with what bits are stuck, so I can verify that the same bits are stuck next time.)

The 'all zeros' trick does work also, sometimes. So it's good to have a set of files containing all zeros, for all of the common sizes, and always try programming them to all zeros, then erasing them (which makes them all ones) a couple of times, which sometimes works also.

These tricks may be obvious to old-timers, but I never really knew about them until I started doing a lot of burning.
 
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