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+--- Thread: EPROM ERASER (/thread-95.html)
EPROM ERASER - someone - 03-03-2020
EPROM Erasers were in common use in the age of the MicroBee.
Early models of the microbee used EPROMs before being replaced with cheaper masked programed ROMs.
It was common practice to erase an old version of MWBASIC to a later one hence the scarcity of early version of MWBASIC.
A common model of retail EPROM Eraser is the Ango LA6A. It has a wavelength 2540 Angstroms. (i.e. 254nm).
RE: EPROM ERASER - Robert - 03-03-2020
My version of Eprom eraser was a special flourescent tube in a standard batten. The eproms were placed in the tiny space between the tube and batten, a cardboard box placed over the top, then left on for a while. Can't remember how long it had to be irradiated (maybe 25 minutes? it's been too long ago)
One problem I noticed is if I programmed a Eprom then tried to erase it wouldn't work properly. Leaving the Eprom for a few days before erasure seemed to sort it out.
I still have the tube and batten, I suppose it might still work.
RE: EPROM ERASER - Ernest - 03-03-2020
Not as efficient, but a cheep alternative is an insect lamp (as used in outdoor Insect Zapper) these emit a reasonable amount of UV in the right frequency to do the job.
Typically my old lamp takes about a 25 hours to erase an EPROM, not 25 minutes, but all fine if you are not in a hurry.
Ernest
RE: EPROM ERASER - someone - 04-03-2020
(03-03-2020, 09:44 PM)Robert Wrote: My version of Eprom eraser was a special flourescent tube in a standard batten. The eproms were placed in the tiny space between the tube and batten, a cardboard box placed over the top, then left on for a while. Can't remember how long it had to be irradiated (maybe 25 minutes? it's been too long ago)
This was a very common method in the 1970-1980's even used at the microbee factory. Rather than a standard sized batten, a desktop fluoro lamp with UV tube fitted was used and the ICs placed on the desk and covered by an internally silvered cardboard shroud.
Be careful when using UV light sources - exposure can be dangerous to the eyes and skin.
(03-03-2020, 11:30 PM)Ernest Wrote: Not as efficient, but a cheep alternative is an insect lamp (as used in outdoor Insect Zapper) these emit a reasonable amount of UV in the right frequency to do the job.
Typically my old lamp takes about a 25 hours to erase an EPROM, not 25 minutes, but all fine if you are not in a hurry.
Sunlight can also work if you have the patience of Jobe.
Modern LEDs are are much more efficient and now come in a variety of wavelengths particularly for agriculture where "LED recipes" are used to optimise the growth of the produce.
These recipes often exclude green thus the plant leaves look black under the LED light. Very strange!
https://www.we-online.com/catalog/en/WL-SMDC_HORTICULTURE/
https://www.we-online.com/catalog/en/WL-SUMW/
You can become your own CSI with this!
https://eshop.wurth.com.au/Product-categories/LED-pocket-torch-UV/31022001050121.cyid/3102.cgid/en/GB/AUD/
RE: EPROM ERASER - Robert - 04-03-2020
This interesting tidbit shows how necessary the sticker over the window is:
Quote:The erasure characteristics of the M2732A are such that erasure begins when the cells are exposed to light with wavelengths shorter than approximately 4000 Å. It should be noted that sunlight and certain types of fluorescent lamps have wavelengths in the 3000-4000 Å range. Research shows that constant exposure to room level fluorescent lighting could erase a typical M2732A in approximately 3 years, while it would take approximately 1 week to cause erasure when exposed to the direct sunlight. If the M2732A is to be exposed to these types of lighting conditions for extended periods of time, it is suggested that opaque labels be put over the M2732A window to prevent unintentional erasure.
Even though it would take the sun a week to erase the whole chip, one or two locations could be changed within hours.
RE: EPROM ERASER - ChickenMan - 04-03-2020
I currently use one of those cheap Chinese UV units as sold on ebay, works well and all done in under 10 minutes and you can get about 8 in the little draw as well. Thats better than a week in direct sunlight
