Uv Erasing Eproms

[ChristianFletcher]

I find myself without eprom eraser and tried using a UV light source of the type used by the ladies for curing nails or polish or something?

I had the Eprom sat on one of the tubes for about 30 minutes and it hasn’t erased. I’m sure this is a strong source of UV as I have been using it for UV exposure of circuit boards and also for curing UV glue and Resins.

Any idea why it won’t erase an Eprom?

[wave solder]

The light that you are using is the wrong frequency, what you need is a fluorescent lamp of the type used in pond filters (UVC).

These lamps generate ozone and can cause burns and eye damage too.

[ChristianFletcher]

Ok that makes sense and jogs the memories. Looks like I will have to buy a cheap eraser from eBay.

Thanks for the reply we live and learn!

[emeritus]

I have never used PROMs myself, but the late 1970's a former colleague who had moved to another firm where they did, mentioned that they had discovered that their cheap non-erasable PROMS (with the same chip as the expensive erasable types used in development but without the quartz window) could be erased using a microwave oven. I don't recall the type of PROM or how much power or length of time was used.

[Radio Wrangler]

Originally Posted by ChristianFletcher

I’m sure this is a strong source of UV as I have been using it for UV exposure of circuit boards and also for curing UV glue and Resins.

You've just run into something that pulled out the foundation of physics, just at a time when physicists were rather smugly thinking that everything to be discovered had almost been discovered.

Your UV light source may have been powerful in terms of sourcing lots and lots of photons of electromagnetic radiation, but the photons themselves were lower in frequency and not so energetic compared to shorter wavelength ones.

To knock an electron loose from an atom, and thereby start spme conduction happening is the photo-electric effect. Only one photon can hot an atom at one time, and if it hasn't got the energy to loosen an electron, nothing happens. It doesn't matter how many photons you have, if the energy of each is inadequate. This is the difference between ionising and non-ionising radiation. It's why radio waves and light are safe, long wave UV is fairly safe, and short wave UV is getting dangerous, X-rays are more dangerous and Gamma is very dangerous.

Some molecules can be made to be rather fragile, so that a photon of nice safe low frequency stuff like light will trigger them into decomposing or even joining up with other materials present. This is how old chemical film photography worked, it's how long wave UV can trigger some resins to cure. As a result those people wanting nail varnish hardening don't take risks with cancer.

Analysis od the quirks of the photoelectric effect produced evidence of quantisation and led to the development of Quantum Mechanics theories. One Dr Einstein was a main researcher on the photoelectric effect and got his Nobel prize for it (not for relativity!) Ironically, he refused to believe in quantum mechanics!

So the wavelength of your UV sets whether your photons are energetic enough to play skittles with supposedly stable electrons. THe brightness of your UV says how many are on the go at once.

Short wavelength UV is used in Eprom erasers, it's also used in tubes for irradiating and sterilising drinking water. A lot of people with private water sources have a tubular device with a hard UV tube in it to kill off any nasties. Most mercury discharge (black light) tubes make short wavelength UV internally, but ordinary glass attenuates it a lot. Short wavelength tubes are quartz, not glass, to make them transparent at these wavelengths.

It's amazing where some of the things tripped over on a daily basis can lead.

Oh and in passing, we drove a stake through the heart of those 5G conspiracy theories.

David

Nearly forgot! A sunny day may do the job slowly.

[factory]

Originally Posted by emeritus

I have never used PROMs myself, but the late 1970's a former colleague who had moved to another firm where they did, mentioned that they had discovered that their cheap non-erasable PROMS (with the same chip as the expensive erasable types used in development but without the quartz window) could be erased using a microwave oven. I don't recall the type of PROM or how much power or length of time was used.

We had this mentioned before, but not properly tested with non-windowed types, as someone tried a UV-EPROM in a microwave and it exploded, probably due to the quartz window & lots of plasma same as abusing lamps in one. If I remember the thread got closed quite quickly.

The OP needs a UV eraser, I think the one at work had one of the germicidal type UV lamp inside, quartz glass type?, the drawer for the ICs had an interlock for obvious reasons. It got opened when the PAT machine didn't like it for the earth bond check, improvements were made to get it to pass.

David

[ChristianFletcher]

Thanks for the information. I am looking to buy an eraser now but I needed one for a Sunday afternoon project. I thought there may be enough of the UVC leaking past the tube coating to do the job but no. I didn't know the frequency was so important and very interesting. I will wait for something to appear at the right price as its probably only going to get used once or twice so I don't want to spend much etc.

Thanks for the great info and comments Regards chris

[kalee20]

Originally Posted by Radio Wrangler

Analysis od the quirks of the photoelectric effect produced evidence of quantisation and led to the development of Quantum Mechanics theories. One Dr Einstein was a main researcher on the photoelectric effect and got his Nobel prize for it (not for relativity!) Ironically, he refused to believe in quantum mechanics!

It's lovely isn't it... Sir Isaac Newton believing light was minute corpuscles, the Continentals maintaining light is a wave motion, almost every experiment supporting the wave theory... then along comes Albert E and shows that Newton was not wrong after all!

[Roger Ramjet]

Originally Posted by ChristianFletcher

I find myself without eprom eraser and tried using a UV light source of the type used by the ladies for curing nails or polish or something?

I had the Eprom sat on one of the tubes for about 30 minutes and it hasn’t erased. I’m sure this is a strong source of UV as I have been using it for UV exposure of circuit boards and also for curing UV glue and Resins.

Any idea why it won’t erase an Eprom?

Hi Christian, I have a large briefcase professional chip programmer & matching UV light unit that I rescued just before being skipped from a company I worked for in the mid 90's. I was intending to offer them FOC on parts for offer but not sure how to add piccy's to the post. Rog

[Cobaltblue]

Hi Rog

Graham did a guide to adding pictures here:

https://www.vintage-radio.net/forum/...ad.php?t=77650

Cheers

Mike T

[Roger Ramjet]

Thanks Mike, that's solved my query. Will wait to see if Christian comes back to me. noting a visit to attic is required to get at the equipment. Rog

[ChristianFletcher]

Hello Roger I would be very interested in the eraser as I am thinking of taking and interest in vintage computing and maybe building a simple Z80 project. I will send you a PM later today as i am travelling this morning. Many thanks.

Chris

[Hartley118]

Originally Posted by kalee20

It's lovely isn't it... Sir Isaac Newton believing light was minute corpuscles, the Continentals maintaining light is a wave motion, almost every experiment supporting the wave theory... then along comes Albert E and shows that Newton was not wrong after all!

....and today string theory suggests that they were both right. We can use whichever model appeals in the circumstances. There's lots of tricky fundamental stuff in optics.

Martin

[rjmusto]

I’ve found a UV steriliser lamp for water sanitation does the job very nicely. Chips erased after 20min.
(I just happen to have one spare in the shed…long story.)

So the cheaper pond versions should work I guess.

[broadgage]

The UV-C lamps used for water treatment are indeed what is required.
These lamps are not in fact fluorescent as they contain no fluorescent powder, but are in practice considered as a sub-species of fluorescent tubes.

They are clear lamps without any white coating.

They operate from the same control gear as ordinary fluorescent lamps of the same dimensions and wattage.

Use of longer wavelength UV might work with patience, as will sunlight.

In the absence of a proper eraser, a bare lamp will work fine, BUT TAKE GREAT CARE. THE LIGHT IS DANGEROUS TO THE EYES AND SKIN. Place the chip to be erased close the unlit lamp, turn it on at arms length and leave the area.

[ChristianFletcher]

Just to finish off the story my friends bought me an eprom eraser at the Dunstable Downs rally. Buyer beware as it was actually a UV exposure unit for making PCB boards but it is the thought that counts. Still It will be useful as I do enjoy making my own PCBs and didnt have a good exposure unit. I can confirm it wont erase an eproms but I did find a tiny UVC lamp for £4.50 on Amazon. This is very lower power but does work very quickly.

The full story is here for anyone that would like to have closer look.
Link to my Youtube Channel: https://youtu.be/5IFZjl-u0Ig


Thanks Regards Chris