16 Sep
2007
16 Sep
'07
1:43 a.m.
Is there anything I need to look out for when purchasing an EPROM
eraser? As part of my current project I'm looking to purchase one.
Zane
--
| Zane H. Healy | UNIX Systems Administrator |
| healyzh at aracnet.com (primary) | OpenVMS Enthusiast |
| MONK::HEALYZH (DECnet) | Classic Computer Collector |
+----------------------------------+----------------------------+
| Empire of the Petal Throne and Traveller Role Playing, |
| PDP-10 Emulation and Zane's Computer Museum. |
| http://www.aracnet.com/~healyzh/ |
16 Sep
16 Sep
1:48 a.m.
On Sep 16, 2007, at 1:43 AM, Zane H. Healy wrote:
Is there anything I need to look out for when
purchasing an EPROM
eraser? As part of my current project I'm looking to purchase one.
Yes...Most EPROM erasers have that black static-dissipative foam
in them to stick the chips in, and it will disintegrate and turn into
a huge mess when it gets old. If you buy an older one, you might be
in for some cleaning.
-Dave
--
Dave McGuire
Port Charlotte, FL
Farewell Ophelia, 9/22/1991 - 7/25/2007
2:09 a.m.
Dave McGuire wrote:
On Sep 16, 2007, at 1:43 AM, Zane H. Healy wrote:
And every eraser I've seen on a professional's bench had either bare
metal or a sheet of mylar on the floor.
I just got a Data IO 29B from a friend, so I asked the guys at MC
Howard where to get a good cheap eraser. Mel just said "Barber Supply".
He says for hobby work, the barbers' UV sterilizers work great.
Doc
Is there anything I need to look out for when
purchasing an EPROM
eraser? As part of my current project I'm looking to purchase one.
Yes...Most EPROM erasers have that black static-dissipative foam in
them to stick the chips in, and it will disintegrate and turn into a
huge mess when it gets old. If you buy an older one, you might be in
for some cleaning. 
7:36 a.m.
On Sun, 2007-09-16 at 01:09 -0500, Doc Shipley wrote:
Mine has a slotted metal tray that you drop the chips into with their
legs dangling through the bars. It's bare as in not even painted in the
bit that's exposed to UV, just (seemingly) galvanised.
Gordon
Yes...Most
EPROM erasers have that black static-dissipative foam in
them to stick the chips in, and it will disintegrate and turn into a
huge mess when it gets old. If you buy an older one, you might be in
for some cleaning.
And every eraser I've seen on a professional's bench had either bare
metal or a sheet of mylar on the floor. 
10:02 a.m.
Doc Shipley wrote:
<snip>
And every eraser I've seen on a professional's bench had either bare
metal or a sheet of mylar on the floor.
I just got a Data IO 29B from a friend, so I asked the guys at MC
Howard where to get a good cheap eraser. Mel just said "Barber
Supply". He says for hobby work, the barbers' UV sterilizers work great.
I'd watch that whatever the pins set on is conductive. I think you can
get some static effects if you don't have conductive materials in the
thing. I had one that was made in a black plastic bread box, and it had
conductive foam to park the parts in.
If you get a unit that isn't an eraser as suggested in other parts of
the thread that is all I'd watch. Make sure that the other units have
metal to set the parts on, since a barber shop sterilizer may have glass
or such, and not metal.
Jim
11:45 a.m.
I'd watch that whatever the pins set on is
conductive. I think you can
get some static effects if you don't have conductive materials in the
thing. I had one that was made in a black plastic bread box, and it had
conductive foam to park the parts in.
If you get a unit that isn't an eraser as suggested in other parts of
the thread that is all I'd watch. Make sure that the other units have
metal to set the parts on, since a barber shop sterilizer may have glass
or such, and not metal.
My main eraser is a very simple device that I had quite a long time (late
70's or early 80's iirc) - it is a model "U/V 1" made by "L S
Engineering
Inc." of Chatsworth, CA.
It looks almost homemade - it's basically a plastic utility box with a loose
fitting lid. The UV tube and ballast are mounted in the box with a switch on
the side. To use it, you put the lid on the table, position your IC's in
it so the windows are in a row down the middle (It's a good sized box, you
can erase 15-20 EPROMS at once, then put the box on top and turn on the
light. At one point I added a timer from a dryer because I had a habit of
forgetting about it (fortunately, there's lots of spare room in the box).
Anyhow - there's nothing conductive about this thing. It's all plastic. I
tested the lid with a gigaohm range meter and it's not aven slightly
conductive. I've erased LOTS of devices in it, and never had a failure
that couldn't be accounted for (ie: because I left it on overnight).
I don't think it's necessary to use a conductive surface - Given that
most devices being erased are used - ie: have been inserted and removed
multiple times, it is highly unlikely that all the pins would contact
a flat conductive surface. Same for a slotted holder - unlikely that
all pins would be connected. Also, none of the data sheets I've seen on
programming mention connecting the pins together. Can anyone provide a
reference?
Regards,
Dave
I have another portable eraser which is a much smaller but similar
design by "Ultra-Violet Products Inc." of San-Gabriel, CA. It's only
big enough to do 2-3 devices. This one does have a strip of conductive
foam in the bottom the the "lid". My suspicion is that this is mainly
there as a way to secure the chips in position so you can leave them
in it when you move it.
--
dave06a (at) Dave Dunfield
dunfield (dot) Firmware development services & tools: www.dunfield.com
com Collector of vintage computing equipment:
http://www.classiccmp.org/dunfield/index.html
1:15 p.m.
At 7:02 AM -0700 9/16/07, jim wrote:
Doc Shipley wrote:
I did a quick Google, and it appears that it would be more difficult
and expensive to get a barber's UV sterilizer than a proper EPROM
eraser.
In any case it sounds like any *cheap* EPROM eraser should be plenty
good enough for me. :^)
Zane
--
| Zane H. Healy | UNIX Systems Administrator |
| healyzh at aracnet.com (primary) | OpenVMS Enthusiast |
| MONK::HEALYZH (DECnet) | Classic Computer Collector |
+----------------------------------+----------------------------+
| Empire of the Petal Throne and Traveller Role Playing, |
| PDP-10 Emulation and Zane's Computer Museum. |
| http://www.aracnet.com/~healyzh/ |
<snip>
And every eraser I've seen on a professional's bench had either
bare metal or a sheet of mylar on the floor.
I just got a Data IO 29B from a friend, so I asked the guys at MC
Howard where to get a good cheap eraser. Mel just said "Barber
Supply". He says for hobby work, the barbers' UV sterilizers work
great.
I'd watch that whatever the pins set on is conductive. I think you
can get some static effects if you don't have conductive materials
in the thing. I had one that was made in a black plastic bread box,
and it had conductive foam to park the parts in.
If you get a unit that isn't an eraser as suggested in other parts
of the thread that is all I'd watch. Make sure that the other units
have metal to set the parts on, since a barber shop sterilizer may
have glass or such, and not metal. 
17 Sep
17 Sep
4:53 a.m.
On Sunday 16 September 2007 18:15:16 Zane H. Healy wrote:
I did a quick Google, and it appears that it would be
more difficult
and expensive to get a barber's UV sterilizer than a proper EPROM
eraser.
In any case it sounds like any *cheap* EPROM eraser should be plenty
good enough for me. :^)
Mine is a pretty big thing (takes about a dozen chips). It was about 30 quid
off eBay. I think it's quite old, but it all seems to work.
Gordon
16 Sep
16 Sep
4:08 p.m.
On Sep 16, 2007, at 10:02 AM, jim wrote:
This is very true. EPROMs store their bits in "floating gates",
which are conductive areas which are totally surrounded by an
insulating material. Exposure to UV light causes that insulating
material to become partially conductive, allowing the charge to drain
<snip>
And every eraser I've seen on a professional's bench had either
bare metal or a sheet of mylar on the floor.
I just got a Data IO 29B from a friend, so I asked the guys at
MC Howard where to get a good cheap eraser. Mel just said "Barber
Supply". He says for hobby work, the barbers' UV sterilizers work
great.
I'd watch that whatever the pins set on is conductive. I think you
can get some static effects if you don't have conductive materials
in the thing. I had one that was made in a black plastic bread
box, and it had conductive foam to park the parts in.
If you get a unit that isn't an eraser as suggested in other parts
of the thread that is all I'd watch. Make sure that the other
units have metal to set the parts on, since a barber shop
sterilizer may have glass or such, and not metal. from the floating gate...and that charge has to GO
somewhere.
-Dave
--
Dave McGuire
Port Charlotte, FL
Farewell Ophelia, 9/22/1991 - 7/25/2007
10:41 p.m.
Dave McGuire wrote:
On Sep 16, 2007, at 10:02 AM, jim wrote:
The gate charge 'goes' to the other side of the gate insulating material,
within the chip. The gate charge does not charge the chip relative to the
rest of the world, so it does not have to 'leave' the chip (if that is
what you are suggesting).
I'd watch that whatever the pins set on is
conductive. I think you
can get some static effects if you don't have conductive materials
in the thing. I had one that was made in a black plastic bread
box, and it had conductive foam to park the parts in.
If you get a unit that isn't an eraser as suggested in other parts
of the thread that is all I'd watch. Make sure that the other
units have metal to set the parts on, since a barber shop
sterilizer may have glass or such, and not metal.
This is very true. EPROMs store their bits in "floating gates",
which are conductive areas which are totally surrounded by an
insulating material. Exposure to UV light causes that insulating
material to become partially conductive, allowing the charge to drain
from the floating gate...and that charge has to GO somewhere. 
5:31 p.m.
I'd watch that whatever the pins set on is
conductive. I think you can
get some static effects if you don't have conductive materials in the
thing. I had one that was made in a black plastic bread box, and it had
conductive foam to park the parts in.
Mine is a professional unit (although Brazil-made in 1980's) and hasn't
anything conductive, only a layer of thick black paper on botton. But here
we have not so many static electricity problems :oP
1:48 a.m.
Is there anything I need to look out for when
purchasing an EPROM eraser?
As part of my current project I'm looking to purchase one.
Anything that erases eproms works :o) It is just a ballast and a special
"germicide" lamp that is just a normal fluorescent lamp without the white
powder inside. Never look at it when turned on, it will blind you! A timer
is nice when you use a eraser.
1:57 a.m.
On 15 Sep 2007 at 22:43, Zane H. Healy wrote:
Is there anything I need to look out for when
purchasing an EPROM
eraser? As part of my current project I'm looking to purchase one.
At one time, there was a study to see how long it took to erase an
EPROM (this was in the 27128 era) if left on a sunny windowsill with
the window open (normal window glass blocks a fair amount of short-
wave UV). IIRC, it was about 4 days.
At one time, clothes (tumble) dryers used to have a lamp called an
"ozone lamp". It had a normal medium screw base and IIRC, some made
a simple EEPROM eraser from one by installing it in a socket inside
of a large soup tin/can. It apparently worked pretty well.
In short, anything that provides *short wave* UV will work. So-
called "black lights" and tanning lamps aren't much good in that
department. But you can easily build your own, given the proper
lamp.
Cheers,
Chuck
6:16 a.m.
Is there anything I need to look out for when
purchasing an EPROM
eraser? As part of my current project I'm looking to purchase one.
Make sure it has a timer, or rig up an external timer. All to easy to
forget about it and I've found that EPROMs tend not to work any more
after spending several days under the lamp :-)
--
dave06a (at) Dave Dunfield
dunfield (dot) Firmware development services & tools: www.dunfield.com
com Collector of vintage computing equipment:
http://www.classiccmp.org/dunfield/index.html
7:47 a.m.
On Sun, 2007-09-16 at 05:16 -0500, Dave Dunfield wrote:
How long should you erase EPROMs for? "Until they're done", I suppose,
but does it vary from chip to chip? I tend to stick a big mixed batch
of 2764 up to 27c2001 in (zapping samples blown into EPROMs) and bung it
on for half an hour. The timer on my eraser goes up to 60 minutes.
Gordon
Is there
anything I need to look out for when purchasing an EPROM
eraser? As part of my current project I'm looking to purchase one.
Make sure it has a timer, or rig up an external timer. All to easy to
forget about it and I've found that EPROMs tend not to work any more
after spending several days under the lamp :-)
11:45 a.m.
Make sure it
has a timer, or rig up an external timer. All to easy to
forget about it and I've found that EPROMs tend not to work any more
after spending several days under the lamp :-)
How long should you erase EPROMs for? "Until they're done", I suppose,
but does it vary from chip to chip? I tend to stick a big mixed batch
of 2764 up to 27c2001 in (zapping samples blown into EPROMs) and bung it
on for half an hour. The timer on my eraser goes up to 60 minutes.
4:06 p.m.
On Sep 16, 2007, at 7:47 AM, Gordon JC Pearce wrote:
How long should you erase EPROMs for? "Until they're done", I
suppose,
but does it vary from chip to chip? I tend to stick a big mixed batch
of 2764 up to 27c2001 in (zapping samples blown into EPROMs) and
bung it
on for half an hour. The timer on my eraser goes up to 60 minutes.
It varies from chip to chip, and from eraser to eraser. More
modern parts (EPROM-based PIC microcontrollers for example) can be
erased in less than ten minutes in my eraser. Older EPROMs like
2716s take upwards of half an hour, sometimes 45mins.
-Dave
--
Dave McGuire
Port Charlotte, FL
Farewell Ophelia, 9/22/1991 - 7/25/2007
Is there anything I need to look out for when
purchasing an EPROM
eraser? As part of my current project I'm looking to purchase one.
Make sure it has a timer, or rig up an external timer. All to easy to
forget about it and I've found that EPROMs tend not to work any more
after spending several days under the lamp :-) 
4:37 p.m.
How long should you erase EPROMs for? "Until
they're done", I suppose,
IIRC most data sheets give times of around 20 minutes.
There was a circuit in one of the maganzines (probably Elektor) a few
years back for an intellegent EPROM eraser. It kept on reading out all
the locations of the chip and left the lamp on until all bits read out as
1'sm then gave <n> times more exposure to be sure. Now whether the rest
of the chip (address decoerd sense amplifier, etc) was known to work
correctly when exposed to UV light, so how reliable this test is, is another
matter
-tony
5:38 p.m.
Tony Duell wrote:
Cute idea.
Reading a M2732A data sheet you need a minimum of 15 W-sec/cm^2
to erase with light at 2537 A. With a lamp of 12000 uW/cm^2 that
is about 15 to 20 min. The recommend the chip be about 2.5 cm from the lamp.
How long
should you erase EPROMs for? "Until they're done", I suppose,
IIRC most data sheets give times of around 20 minutes.
There was a circuit in one of the maganzines (probably Elektor) a few
years back for an intellegent EPROM eraser. It kept on reading out all
the locations of the chip and left the lamp on until all bits read out as
1'sm then gave <n> times more exposure to be sure. Now whether the rest
of the chip (address decoerd sense amplifier, etc) was known to work
correctly when exposed to UV light, so how reliable this test is, is another
matter -tony
Ben alias woodelf.
I wonder how much UV the big sparks you see in the lab on old horror
movies are. :)
9:57 a.m.
From: dave06a at dunfield.com> > > Is there
anything I need to look out for when purchasing an EPROM > > eraser? As part of my
current project I'm looking to purchase one.> > Make sure it has a timer, or rig
up an external timer. All to easy to> forget about it and I've found that EPROMs
tend not to work any more> after spending several days under the lamp :-)>
Hi
When working at Intel we used to fix these by baking them
in an oven. I don't recall the temperature but it was very
hot.
I've always erases for about 25% longer then it takes to
look erased from the programmer. The time varies from
eraser to eraser and also from EPROM type.
Newer EPROMs only seem to need about 10 minutes in
the eraser that I use most of the time. Those that require
20 volts or more to program seem to take longer.
You need a quartz tube murcury lamp to erase. Many
have used dryer lamps. Any lamp from an ozone generator
should work ( many have these on hot tubes ).
If you have a way to keep it cool, a quartz halogen
lamp might work but I've never given this a try.
A carbon arc would work as well but I've not seen these
since they've stopped using these in search lights.
Dwight
_________________________________________________________________
Gear up for Halo? 3 with free downloads and an exclusive offer. It?s our way of saying
thanks for using Windows Live?.
http://gethalo3gear.com?ocid=SeptemberWLHalo3_WLHMTxt_2
7:35 p.m.
On 16 Sep 2007 at 21:40, Tony Duell wrote:
Ah well, you'll just have to use a magnesium flare, then (IIRC, lots
of UV output).
As your UV eraser bulb ages, the output will gradually decrease. So
you may find that you may need to gradually increase the erasure
time.
Of course, magnesium flares don't have that problem... ;)
Cheers,
Chuck
A carbon arc
would work as well but I've not seen these
since they've stopped using these in search lights.
And if the arc happens to jump to the pins of the EPROM, it'll surely be
erased, but not, alas, reporgrammable. 
10:21 p.m.
I built my own EPROM eraser quite a while back. It's
not hard, and it was a fun afternoon project. It
turned out very well.
Basically, I used:
-A germicidal tube. This was purchased at a PetSmart
locally. It is intended for a pond filter to kill
bacteria.
-A cheap fluorescent light fixture that takes the
appropriate bulb (12" T6, IIRC) as the germicidal
tube.
-A broken microwave oven
-A case scavenged from a junk QIC style tape drive
-scrap pine board
I built a wooden drawer that slid into a simple sealed
wooden box and built that into the metal tape drive
case. Inside this box, I mounted the light fixture
(with it's white diffusion cover removed), and a
microswitch that it is closed when the drawer was
fitted all the way in. The microwave's control board
and display were recycled into a standalone timer,
rigged into the light fixture, and the door switch
wired in the same way the microwave's door switch was.
I replaced the horrid membrane microwave keypad with
the keypad sawed off the end of a junked Apple IIe
Platinum keyboard. Once I got everything wired up and
tested, I swapped in the UV tube (always practice with
the tube that came with the fixture - you know, the
one that won't burn your skin off)
The end result, I have an aluminum box with a wooden
drawer in the front, and inside a wooden, sealed box
containing the UV light. The tray is a simple flat
board on which I can line up as many EPROMs as I want
(up to a foot of chips). On the front of my device is
a keypad and a display, and I can type in the amount
of minutes I want it to run for, and start it - it
shuts off when the time runs out, or if I open the
drawer. It also doubles as a clock.
Very handy. A little cobbled-together looking, but it
works very well.
-Ian
6154
days inactive
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