Clearing EPROMS/EEPROMS

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Colday
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Clearing EPROMS/EEPROMS

Post by Colday » Sat Aug 08, 2020 11:53 am

I have a few old 27128's and 2764D EPROMS/EEPROMS that I want to 'blank'.

Is there a specific frequency of UV light that works best? I've been looking at a cheap UV torch on FleaBay that is at 395nm.

https://www.ebay.co.uk/itm/Aluminum-Hig ... SwYIxX7WBC

Can anyone advise if this would suffice?

I will be buying a few other 'blanks' once I find a decent source, but want to put tricky's test ROM onto one of these.

The 2764D's show as blank already but error out when I try to write to them so want to hit them with a dose of UV before giving up.
BBC B's... I now have 6!
I also have 1 boxed with manuals, unmolested model A.
And also an unmolested model B. (but not boxed sadly)
12x floppy drives (only 1x currently works I think)...
Learning to repair and refurb keyboards next! No more sticky keys!

Colday
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Re: Clearing EPROMS/EEPROMS

Post by Colday » Sat Aug 08, 2020 1:45 pm

Ignore this. I bought a designated EPROM eraser rather than this faff.
BBC B's... I now have 6!
I also have 1 boxed with manuals, unmolested model A.
And also an unmolested model B. (but not boxed sadly)
12x floppy drives (only 1x currently works I think)...
Learning to repair and refurb keyboards next! No more sticky keys!

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Wheel_nut
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Re: Clearing EPROMS/EEPROMS

Post by Wheel_nut » Sat Aug 08, 2020 2:40 pm

Good decision. I have one of those UV Torches and leaving it on for two days directly above the window of a 27nnn EPROM did absolutelt nothing to clear the data.
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Colday
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Re: Clearing EPROMS/EEPROMS

Post by Colday » Sat Aug 08, 2020 4:54 pm

Wheel_nut wrote:
Sat Aug 08, 2020 2:40 pm
Good decision. I have one of those UV Torches and leaving it on for two days directly above the window of a 27nnn EPROM did absolutelt nothing to clear the data.
Hahaha!

Very glad I have chosen the proper route. Although went for a cheap version the reviews said it wiped a 2764 in 15 mins. Lol.
BBC B's... I now have 6!
I also have 1 boxed with manuals, unmolested model A.
And also an unmolested model B. (but not boxed sadly)
12x floppy drives (only 1x currently works I think)...
Learning to repair and refurb keyboards next! No more sticky keys!

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vanekp
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Re: Clearing EPROMS/EEPROMS

Post by vanekp » Sat Aug 08, 2020 7:49 pm

I bought a very cheap one from Aliexpress it seems to work well so far.
Peter.

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Re: Clearing EPROMS/EEPROMS

Post by Kazzie » Sat Aug 08, 2020 8:01 pm

vanekp wrote:
Sat Aug 08, 2020 7:49 pm
I bought a very cheap one from Aliexpress it seems to work well so far.
That looks identical to the one I bought via eBay. It's just a box with a bulb and a drawer, and a mechanical timer, but it does the job nicely.

Mine was shipped to the UK with a non-UK plug, but it was easy enough to chop that off and fit a new one on.
BBC Model B 32K issue 7, Sidewise ROM board with 16K RAM
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vanekp
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Re: Clearing EPROMS/EEPROMS

Post by vanekp » Sat Aug 08, 2020 8:04 pm

yes as you say it does the job and it had the option of the EU plug not that that's much good to you i the UK:)
Peter.

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Re: Clearing EPROMS/EEPROMS

Post by MartinB » Sat Aug 08, 2020 9:08 pm

.
Last edited by MartinB on Sun Aug 09, 2020 11:08 pm, edited 2 times in total.

Colday
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Re: Clearing EPROMS/EEPROMS

Post by Colday » Sun Aug 09, 2020 7:51 pm

So. My Amazon supplied, UK sourced UV EPROM eraser has arrived, next day delivery.

Very impressive.

I shall include a photo in the next post. Spot the issue.
BBC B's... I now have 6!
I also have 1 boxed with manuals, unmolested model A.
And also an unmolested model B. (but not boxed sadly)
12x floppy drives (only 1x currently works I think)...
Learning to repair and refurb keyboards next! No more sticky keys!

Colday
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Re: Clearing EPROMS/EEPROMS

Post by Colday » Sun Aug 09, 2020 7:54 pm

IMG_4679.jpg
BBC B's... I now have 6!
I also have 1 boxed with manuals, unmolested model A.
And also an unmolested model B. (but not boxed sadly)
12x floppy drives (only 1x currently works I think)...
Learning to repair and refurb keyboards next! No more sticky keys!

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IanS
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Re: Clearing EPROMS/EEPROMS

Post by IanS » Sun Aug 09, 2020 8:03 pm

Did they include a death-dapter?

Colday
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Re: Clearing EPROMS/EEPROMS

Post by Colday » Sun Aug 09, 2020 8:15 pm

Inside is actually worse.
IMG_4680.jpg
How many infractions of the UK electrical code can we find?
BBC B's... I now have 6!
I also have 1 boxed with manuals, unmolested model A.
And also an unmolested model B. (but not boxed sadly)
12x floppy drives (only 1x currently works I think)...
Learning to repair and refurb keyboards next! No more sticky keys!

Colday
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Re: Clearing EPROMS/EEPROMS

Post by Colday » Sun Aug 09, 2020 8:16 pm

Still, I've stuck a UK plug on it.... and it works.

Will be only operated in a steel box insulated electrically and by heat/fire.

Somewhere in a field... possibly in mid wales. (pick your remote county of choice)
BBC B's... I now have 6!
I also have 1 boxed with manuals, unmolested model A.
And also an unmolested model B. (but not boxed sadly)
12x floppy drives (only 1x currently works I think)...
Learning to repair and refurb keyboards next! No more sticky keys!

Colday
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Re: Clearing EPROMS/EEPROMS

Post by Colday » Sun Aug 09, 2020 9:34 pm

Well, I'm utterly stuck with these.

The UV seems to blank them perfectly as the programmer now sees them as blank (and reports as such). But can I get them to write?

Nope.

Just getting errors. This sucks.
BBC B's... I now have 6!
I also have 1 boxed with manuals, unmolested model A.
And also an unmolested model B. (but not boxed sadly)
12x floppy drives (only 1x currently works I think)...
Learning to repair and refurb keyboards next! No more sticky keys!

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1024MAK
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Re: Clearing EPROMS/EEPROMS

Post by 1024MAK » Sun Aug 09, 2020 10:19 pm

Colday wrote:
Sun Aug 09, 2020 8:15 pm
Inside is actually worse.

How many infractions of the UK electrical code can we find?
That’s normal for items made in China for export...

Mark

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Re: Clearing EPROMS/EEPROMS

Post by BeebMaster » Sun Aug 09, 2020 10:21 pm

If they are old EPROMs they might use a programming voltage of 21V instead of 12V. What programmer are you using?
Image

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1024MAK
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Re: Clearing EPROMS/EEPROMS

Post by 1024MAK » Sun Aug 09, 2020 10:22 pm

Colday wrote:
Sun Aug 09, 2020 9:34 pm
Well, I'm utterly stuck with these.

The UV seems to blank them perfectly as the programmer now sees them as blank (and reports as such). But can I get them to write?

Nope.

Just getting errors. This sucks.
I presume you are talking about your 2764 EPROMs. Are they 12V, 21V or 25V devices? Some USB programmers are not capable of supplying enough power at 21V or 25V to actually program the older EPROM chips.

Mark

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Re: Clearing EPROMS/EEPROMS

Post by Colday » Sun Aug 09, 2020 10:38 pm

1024MAK wrote:
Sun Aug 09, 2020 10:19 pm
Colday wrote:
Sun Aug 09, 2020 8:15 pm
Inside is actually worse.

How many infractions of the UK electrical code can we find?
That’s normal for items made in China for export...

Mark
A little surprised Amazon are supplying them from a UK shipping address in this fashion though

Not had that before. Can feel a call/email to trading standards coming on.
BBC B's... I now have 6!
I also have 1 boxed with manuals, unmolested model A.
And also an unmolested model B. (but not boxed sadly)
12x floppy drives (only 1x currently works I think)...
Learning to repair and refurb keyboards next! No more sticky keys!

Colday
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Re: Clearing EPROMS/EEPROMS

Post by Colday » Sun Aug 09, 2020 10:40 pm

Think my programmer is limited to 18v.

Which would be typical of my luck.

Sigh. I'll await my lower rated chips before I am able to write Tricky's test ROM I guess.

Onto the drives I suppose!
BBC B's... I now have 6!
I also have 1 boxed with manuals, unmolested model A.
And also an unmolested model B. (but not boxed sadly)
12x floppy drives (only 1x currently works I think)...
Learning to repair and refurb keyboards next! No more sticky keys!

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1024MAK
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Re: Clearing EPROMS/EEPROMS

Post by 1024MAK » Sun Aug 09, 2020 10:44 pm

Colday wrote:
Sun Aug 09, 2020 10:38 pm
1024MAK wrote:
Sun Aug 09, 2020 10:19 pm
Colday wrote:
Sun Aug 09, 2020 8:15 pm
Inside is actually worse.

How many infractions of the UK electrical code can we find?
That’s normal for items made in China for export...

Mark
A little surprised Amazon are supplying them from a UK shipping address in this fashion though

Not had that before. Can feel a call/email to trading standards coming on.
It could be a Chinese company that holds stock in a U.K. based warehouse. There was/is one near my town.

Mark

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Re: Clearing EPROMS/EEPROMS

Post by Kazzie » Sun Aug 09, 2020 10:46 pm

Colday wrote:
Sun Aug 09, 2020 8:16 pm
Still, I've stuck a UK plug on it.... and it works.

Will be only operated in a steel box insulated electrically and by heat/fire.

Somewhere in a field... possibly in mid wales. (pick your remote county of choice)
Make sure it's "mid", not "north", please! :shock:
BBC Model B 32K issue 7, Sidewise ROM board with 16K RAM
Archimedes 420/1 upgraded to 4MB RAM, ZIDEFS with 512MB CF card
RiscPC 600 under repair
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Re: Clearing EPROMS/EEPROMS

Post by Colday » Mon Aug 10, 2020 9:07 am

Well, if you see a fiery glow in the sky south of you Kazzie, you can probably guess what has caused it.

I'm now struggling with programming the bloody things now I have blanked them.

Ah well. Onwards. So far none of them have taken an image. They all error out. And I have no idea what is causing it.

I need to find the data sheets for the EPROM's so I can see what voltage they need to blow and image to them.
BBC B's... I now have 6!
I also have 1 boxed with manuals, unmolested model A.
And also an unmolested model B. (but not boxed sadly)
12x floppy drives (only 1x currently works I think)...
Learning to repair and refurb keyboards next! No more sticky keys!

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Re: Clearing EPROMS/EEPROMS

Post by vanekp » Mon Aug 10, 2020 11:11 am

Colday wrote:
Mon Aug 10, 2020 9:07 am
Well, if you see a fiery glow in the sky south of you Kazzie, you can probably guess what has caused it.

I'm now struggling with programming the bloody things now I have blanked them.

Ah well. Onwards. So far none of them have taken an image. They all error out. And I have no idea what is causing it.

I need to find the data sheets for the EPROM's so I can see what voltage they need to blow and image to them.
what are the exact numbers on the chip, quite often the program voltage is also printed on the chip.
Peter.

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Re: Clearing EPROMS/EEPROMS

Post by Kazzie » Mon Aug 10, 2020 11:58 am

I'm using an antediluvian ART EPP1 programmer, which expects me to tell it every parameter directly: referencing datasheets is standard practice with that one. ;)
BBC Model B 32K issue 7, Sidewise ROM board with 16K RAM
Archimedes 420/1 upgraded to 4MB RAM, ZIDEFS with 512MB CF card
RiscPC 600 under repair
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Re: Clearing EPROMS/EEPROMS

Post by Kazzie » Mon Aug 10, 2020 11:59 am

Colday wrote:
Mon Aug 10, 2020 9:07 am
Well, if you see a fiery glow in the sky south of you Kazzie, you can probably guess what has caused it.
I did see one of those to the south this morning, but it turns out it was just the sun. 8)
BBC Model B 32K issue 7, Sidewise ROM board with 16K RAM
Archimedes 420/1 upgraded to 4MB RAM, ZIDEFS with 512MB CF card
RiscPC 600 under repair
Acorn System 1 home-made replica

Colday
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Re: Clearing EPROMS/EEPROMS

Post by Colday » Mon Aug 10, 2020 1:40 pm

I know Wales is 'foreign lands' but I'm pretty sure the sun doesn't rise in the south.

Haha.

As for vanekp, these are original EPROMS and don't seem to have the voltages on..

For instance the one I'm looking at has the following on the chip...

Japan 8434
00009SS0
HN4827128G-25

So, made in 34th week of 1984 in Japan...

I'm 98% sure that second line is correct - I have to wear a magnifying headset to see these tiny faded letters.
And the 3rd line is correct for sure.

Then there is a Mitsubishi chip

M5L27128K-2
730108 or B (difficult to tell)
Japan

Then I have 2x NEC

D2764D
8232K6205

These obviously came out of the same batch as they are identical in every way.
BBC B's... I now have 6!
I also have 1 boxed with manuals, unmolested model A.
And also an unmolested model B. (but not boxed sadly)
12x floppy drives (only 1x currently works I think)...
Learning to repair and refurb keyboards next! No more sticky keys!

Kazzie
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Re: Clearing EPROMS/EEPROMS

Post by Kazzie » Mon Aug 10, 2020 4:44 pm

Colday wrote:
Mon Aug 10, 2020 1:40 pm
I know Wales is 'foreign lands' but I'm pretty sure the sun doesn't rise in the south.

Haha.
Well, perhaps it was more south-east than south.

I could make comments about certain maps in Hereford that put east at the top, but I'd probably be digging myself into a deeper hole.
Colday wrote:
Mon Aug 10, 2020 1:40 pm
these are original EPROMS and don't seem to have the voltages on..
HN4827128G-25
That one requires 21V programming voltage. Here's a datasheet I found online by searching for that part number:
HN4827128G.pdf
(124.78 KiB) Downloaded 14 times
Colday wrote:
Mon Aug 10, 2020 1:40 pm
Then there is a Mitsubishi chip

M5L27128K-2
21V again:
M5L27128K.PDF
(395.29 KiB) Downloaded 11 times
Colday wrote:
Mon Aug 10, 2020 1:40 pm
Then I have 2x NEC

D2764D
The nearest match I found was an NEC uPD2764, which is yet another 21V part. :(
NEC-UPD2764.PDF
(277.4 KiB) Downloaded 13 times
BBC Model B 32K issue 7, Sidewise ROM board with 16K RAM
Archimedes 420/1 upgraded to 4MB RAM, ZIDEFS with 512MB CF card
RiscPC 600 under repair
Acorn System 1 home-made replica

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vanekp
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Re: Clearing EPROMS/EEPROMS

Post by vanekp » Mon Aug 10, 2020 4:47 pm

Colday wrote:
Mon Aug 10, 2020 1:40 pm
I know Wales is 'foreign lands' but I'm pretty sure the sun doesn't rise in the south.

Haha.

As for vanekp, these are original EPROMS and don't seem to have the voltages on..

For instance the one I'm looking at has the following on the chip...

Japan 8434
00009SS0
HN4827128G-25

So, made in 34th week of 1984 in Japan...

I'm 98% sure that second line is correct - I have to wear a magnifying headset to see these tiny faded letters.
And the 3rd line is correct for sure.

Then there is a Mitsubishi chip

M5L27128K-2
730108 or B (difficult to tell)
Japan

Then I have 2x NEC

D2764D
8232K6205

These obviously came out of the same batch as they are identical in every way.
HN4827128G-25 specs hear https://www.datasheets360.com/pdf/5583574220728082918
it would appear the programing voltage (Vpp) is 12.5v
and the NEC D2764D have a programing voltage (Vpp) of 21v https://www.silicon-ark.co.uk/datasheet ... et-nec.pdf
I am sure I have been able to program the 21v ones at 18v on my TL866 II plus.
Peter.

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Re: Clearing EPROMS/EEPROMS

Post by Kazzie » Mon Aug 10, 2020 4:58 pm

vanekp wrote:
Mon Aug 10, 2020 4:47 pm
HN4827128G-25 specs hear https://www.datasheets360.com/pdf/5583574220728082918
it would appear the programing voltage (Vpp) is 12.5v
That datasheet appears to be for the HN4827128AG. It differs from the HN4827148G datasheet I posted above.
BBC Model B 32K issue 7, Sidewise ROM board with 16K RAM
Archimedes 420/1 upgraded to 4MB RAM, ZIDEFS with 512MB CF card
RiscPC 600 under repair
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vanekp
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Re: Clearing EPROMS/EEPROMS

Post by vanekp » Mon Aug 10, 2020 5:41 pm

ahh did not notice that, my bad, so its also 21v Vpp
Peter.

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