Thoughts on a suitable EPROM Eraser

[Super_7b]

Hi All,

After completing my HCR EPROM Programmer (Thanks Hoglet) I set to and searched for my stash of EPROMs. Today I found them in a box in the cellar that hadn't been opened since we moved house in 2016. I now have about forty 27C64 chips which should be blank and about ten 2732 chips which are probably not blank.

Thus I am in the market for an eraser. Are there any recommended ones? I see many, many seemingly identical devices like this on ebay:-

High Speed UV EPROM Eraser Erase Ultraviolet Eraser Timer Eraser £20.09

Trustworthy second hand models such as ones by Lawtronics or Stag come in at £60.00 and above. Will the cheapy do the business or should I bite the bullet and go for a higher quality maker?

BR

Mick

[Ukwebb]

I've got one of the cheapo ones, and tbh they do the job. I'm sure electrically they're a bit suspect, but for 10 minutes every couple of weeks I'm happy

[1024MAK]

Do the cheapie Far East erasers work? Yes, they do erase EPROMs.

However, do be aware of the err, limitations:

• The timer is hopelessly inaccurate on mine, and I understand this is not uncommon...
• The mains cable is not likely to conform to U.K. standards.
• Any adaptor supplied so it can be used in our 13A sockets will likely have more safety design faults than you’ve had hot dinners (hence a You Tuber dubbed them deathdaptors).
• The internal wiring may be a bit dodgy,
• UV light may leak out as the compartment drawer often does not fit that well.

A few years ago battleship grey was the more common colour...

Mark

[Super_7b]

Thanks for the swift replies guys.

It looks like it's worth a £20.00 punt is in the offing....

BR

Mick

[sweh]

about forty 27C64 chips which should be blank and about ten 2732 chips which are probably not blank.

Huh, not sure it's even worth erasing them; 4k and 8k... No 27128 chips?

[maniacminer]

Huh, not sure it's even worth erasing them; 4k and 8k... No 27128 chips?

They could be used for Tricky's Test ROM, the 2732 is a 24 pin IC so it's useless in the Beeb without a carrier to convert the signals to 28 pin layout.

I've got a cheap eraser from China, "Leap" branded (perhaps what happens when you touch the case ) I bought it in Shenzhen years ago, there's very little to it, an inverter, a micro switch and a mercury lamp in a quartz tube. Bear in mind that the tube needs a few minutes to reach full UV power as its spectral output starts off mainly in the visible and then the UV ratio increases with the temperature of the mercury arc.

[arg]

, the 2732 is a 24 pin IC so it's useless in the Beeb without a carrier to convert the signals to 28 pin layout.

Unless of course you want to go total retro and put OS 0.1 in 4off 2732 across the four sockets....

While that's a crazy idea niche interest, I'm somewhat of the opinion that wanting to use EPROMs at all is also a fairly retro-purist viewpoint, given that even BITD we used to put all sorts of things that weren't EPROMs in those sockets.

I got half way through designing a programmer, but the thought of needing to source suitable EPROMs and find an eraser led me to bin that idea and design some EPROM-shaped plug-in boards for more modern memory technology instead.

Of course there's nothing wrong with being a retro-purist if that's what drives your interest.

[1024MAK]

Well, the easy answer is to buy new OTP EPROMs. Yes, you cannot erase them, but because they come in plastic packages, they are fairly cheep.

For development, sideways RAM is the way to go.

2764 are useful for ZX81s, you can then use the better and faster "big bang" ROM.

Mark

[Gelpack]

I use a Chinese one off ebay, they are all pretty much lookalikes. Mine works great and had it for almost two years now. A little mechanical timer on it allows you to set duration.

[Super_7b]

Huh, not sure it's even worth erasing them; 4k and 8k... No 27128 chips?

The world doesn't revolve around BBCs! I want to program EPROMs for other projects such as Z80 based breadboard devices. 4k is more than sufficient for some of the tasks I have in mind.

I am making use of the Beeb to program them though. And yes, I do have some 27128 chips as well.

[SunbakedinWA]

Having lashed together an EPROM programmer from spare parts and RasPi 400 I too found myself in need of a UV eraser.
The UV curing station for the resin 3D printer was a no, so too was the UV exposure unit for PCB making.

Then I found myself doing the food shop and spotted a UV sterilizer on offer for $30 (Australian) the box said 253.7nm wavelength which is very close to the sweet spot for the AMD EPROMs I was using as trial subjects.
And yes, after 20 mins propped with the EPROM window right next to the light source it read back &FF in every location. YMMV of course!

[coopzone]

I made one using an old camping florescent lamp (12v) and a UV steriliser tube - sold for tropical fish tank units. £2.00 aprox

[nigeb]

I've got one of those cheap chinese erasers too, and I agree with everyone else - it's fine as long as you know its limitations.
I immediately replaced the plug on mine and had the lid off to check the innards. I made sure there was a knot in the cable to stop it being pulled loose, everything else seemed intact but one thing to note is that there's no separation between the circuitry and the area your eproms sit, so if you tip it over while running, your chips could end up in a heap mixed up with all of that.
I did a few trial runs and re-labelled the timer dial but it still isn't accurate because there's a huge amount of play in the mechanism, plus it stops early sometimes. Not a major problem to get around 10-15 minutes out of it, just don't expect accuracy.

[Bitstik]

I have just ordered one of these- one of the reviews stated it was perfect for eprom erasing. I’ll let you know how I get on

[daveejhitchins]

Couldn't resist this. I've always wanted a Lawtronics eraser. Had a 'good' one in the '80s/'90s but don't know what happened to it when I left in '94.

Package was delivered fast! On testing the lamps worked but the timer didn't. Had some fun doing the fix which was just a 'sticky' synchronous motor. A good soak in WD40 and it works a treat. The lamps are driven from a standard Fluorescent circuit. I'm going to replace the starters with the solid-state ones to minimise the damaging effect of the 'standard' starters.

So, that leaves me with one of the cheap Chinese ones. I've not had any problems with this other than capacity. Free with P&P for anyone who would like it - You'll need a mains plug Edit: Given to the charity stall at Wakefields (Bradford) RISC OS Show.

Dave H.

[maniacminer]

Having lashed together an EPROM programmer from spare parts and RasPi 400 I too found myself in need of a UV eraser.
The UV curing station for the resin 3D printer was a no, so too was the UV exposure unit for PCB making.

Then I found myself doing the food shop and spotted a UV sterilizer on offer for $30 (Australian) the box said 253.7nm wavelength which is very close to the sweet spot for the AMD EPROMs I was using as trial subjects.
And yes, after 20 mins propped with the EPROM window right next to the light source it read back &FF in every location. YMMV of course!

It should be *exactly* on the sweet spot for erasing EPROMs as mercury arc lamps are the standard and one of their peak energy line outputs is at 253.65nm (of course the old AMD datasheets from the 80s use Angstroms so 2536.5Å) I used to create calibration lamps with a bead of mercury in an argon filled quartz tube, the ozone will come from the 184.45nm emission line, a special ballast drives the lamp (a fluorescent ballast would work, but it will dramatically cut the life of the lamp)

[maniacminer]

I have just ordered one of these- one of the reviews stated it was perfect for eprom erasing. I’ll let you know how I get on

IMG_4686.png

Interesting. Looking at the product on the Samsung website, there's lots of Chinese company investigations, but their reports seem to be deliberately vague... I wonder if it is using gas discharge tubes or LEDs? I almost want to get one to take it apart (not switch it on) aka Dave Jones The problem with using UV-C for sterilisation is the break down of polymers by free radicals (from the energy in the UV) so I wouldn't want to put anything plastic inside this - although looking at the photo, I'm wondering if it is just some blue LEDs at around 400nm and not the UV-C like 250nm. These products were all the rage during COVID and some very amusing and some very dangerous products got released with the pandemic impetus to make money whilst you can...

[maniacminer]

Couldn't resist this. I've always wanted a Lawtronics eraser. Had a 'good' one in the '80s/'90s but don't know what happened to it when I left in '94.

Package was delivered fast! On testing the lamps worked but the timer didn't. Had some fun doing the fix which was just a 'sticky' synchronous motor. A good soak in WD40 and it works a treat. The lamps are driven from a standard Fluorescent circuit. I'm going to replace the starters with the solid-state ones to minimise the damaging effect of the 'standard' starters.

So, that leaves me with one of the cheap Chinese ones. I've not had any problems with this other than capacity. Free with P&P for anyone who would like it - You'll need a mains plug

Dave H.

Yeah, the good old Lawtronics eraser, there was one at work, a huge thing that could erase an entire board of EPROMs in one go, the photo reminded me of the colour. It had been modified with a pre-start so the lamps got to their peak UV before the board was placed inside, then it was around 10mins per board, the lamps didn't turn off between switch overs (another mod) I think it got recycled, I didn't want it, only now do I think I have enough EPROMs to fill it - and then it would be all of them, all at once

[maniacminer]

A bit OT but I have a dead Sinclair Z88 EPROM eraser, their system was similar to the one I we had a work except instead of 300+M bytes of storage, this is just 64K bytes. The idea is you save files to EPROM on the Z88 and then when it is full, you copy the files you want to RAM, erase the EPROM and then put the files back. It's a bit like a CD-RW where sessions are closed until there's no space and then you just erase the disc and start again (in sequential access mode anyway) Here are a few pics of the guts of it.

Sinclair EPROM eraser PCB top

Sinclair EPROM eraser PCB bottom

[daveejhitchins]

Wow . . . Not seen that one - weird - Dave H.

[Bitstik]

I have just ordered one of these- one of the reviews stated it was perfect for eprom erasing. I’ll let you know how I get on

IMG_4686.png

Interesting. Looking at the product on the Samsung website, there's lots of Chinese company investigations, but their reports seem to be deliberately vague... I wonder if it is using gas discharge tubes or LEDs? I almost want to get one to take it apart (not switch it on) aka Dave Jones The problem with using UV-C for sterilisation is the break down of polymers by free radicals (from the energy in the UV) so I wouldn't want to put anything plastic inside this - although looking at the photo, I'm wondering if it is just some blue LEDs at around 400nm and not the UV-C like 250nm. These products were all the rage during COVID and some very amusing and some very dangerous products got released with the pandemic impetus to make money whilst you can...

It seems to be using very tiny tubes and I confirm it works perfectly. Auto timer for 10 mins - the EPROMs need to be on their side angled towards the tubes which are at either end - I’ll need to make up a holder for them - at present it clears 4 at once in 10 minutes - it’s well made, runs from usb-C and strikes me as considerably safer than the cheap chinese options albeit that this is cheaper and made in China also…

[tom_seddon]

It seems to be using very tiny tubes and I confirm it works perfectly. Auto timer for 10 mins - the EPROMs need to be on their side angled towards the tubes which are at either end - I’ll need to make up a holder for them - at present it clears 4 at once in 10 minutes - it’s well made, runs from usb-C and strikes me as considerably safer than the cheap chinese options albeit that this is cheaper and made in China also…

Thanks for the review! I've ordered one myself now. This sounds a much safer bet than the usual ones that are everywhere on Amazon and eBay.

--Tom

[DaveBurke]

So, that leaves me with one of the cheap Chinese ones. I've not had any problems with this other than capacity. Free with P&P for anyone who would like it - You'll need a mains plug

Dave H.

Could I have that please Dave? I'm managing with a UVC LED at the moment, and it takes quite a while to fully erase an EPROM

[nigeb]

Anyone remember the handheld ones? You could erase a chip in about 15 seconds without removing it from the board! Dodgy as.

[maniacminer]

Anyone remember the handheld ones? You could erase a chip in about 15 seconds without removing it from the board! Dodgy as.

Yeah, I've used one, a xenon flash lamp with a quartz window, made by Dataman I think. It's very handy when the EPROM is awkward to get to and is programmed in-situ.

[Super_7b]

I have just ordered one of these- one of the reviews stated it was perfect for eprom erasing. I’ll let you know how I get on

Thanks for that info. You saved me buying one of the ebay iffy erasers. £22.88 on Amazon delivered next day and it works a treat. The included handbook states the wavelength is 253.7nm, which is what we want and the build quality is good, as you might expect when it is marketed by Samsung.

I cleaned up some 2716 and 27128 EPROMs that came out of some telecoms equipment so I am confident I can clean up any test chips going forward playing with my programmer.

I am not sure what time is actually needed, but 20 minutes with the chips on their side so the window was facing the lamp at a distance of about 12mm worked for me.

BR

Mick

[Bitstik]

That’s great to hear.
I’m finding my Mitsubishi 27c512 EPROMs are fine after the 10 minute auto timer finishes.

[tom_seddon]

Success for me too, and mostly with only 1 x 10 minute sanitize/erase cycle needed. (I had one attempt at doing 4 at once, but only 1 came out fully blank, and the rest needed another go. 1 EPROM per lamp seemed to work fine.)

Is there a recommended distance? I leant the chips right up against the lamp, and they did come out a little warm.

--Tom

[Bitstik]

I angled my EPROMs on the ridges at about 45 degrees to the tubes so the EPROMs weren’t touching the tubes. I manage to wipe 4 at once with two at each end.

[Andy1979]

I have just ordered one of these- one of the reviews stated it was perfect for eprom erasing. I’ll let you know how I get on

IMG_4686.png

Interesting - my wife bought that exact model during Covid, so it turns out I own two Eprom erasers! (also have one of the cheap Chinese ones)

Useful gadget which charges your phone while it allegedly cleans it, and USB-C power eliminates a lot of the risks with the cheaper products.