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jwillis84
USA
5 Posts |
 Posted - 09/23/2015 : 17:13:45
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I have some 26 year old EPROMs which I would like to read and backup to a disk file.
They are soldered onto small circuit boards with plated through via holes in the circuit board.
The EPROMs are labeled:
M27C4001 -15F1 V88A0 ST 9422D
I run Windows XP and Windows 7 on my desktops.
I assume I will need to desolder each EPROM to place it in a ZIF socket to read.
1. Can you recommend the best EPROM reader/burner for this task?
2. Can you suggest the safest method to go about desoldering?
I am concerned the desoldering process might wipe or corrupt the EPROM memory before I can read it.
Would it be safer to cut the Leads on the 32 DIP and use a chip clip?
Thank you
Image Insert:
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| Reply #1
ZLM
2945 Posts |
Posted - 09/26/2015 : 22:27:00
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The GQ-4X works on this chip.
You need to de-solder the chip and then put it on the programmer for reading. When de-soldering chip, try to avoid overheat it for long time. Also, do not break the pin from the chip body.
Your chip is data is more than 25 years. In general, the EPROM data retention time will be around 10-15 years. For your chip, I can only say "Good Luck!" to read the data 100% correct.
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| Reply #2
jwillis84
USA
5 Posts |
Posted - 09/28/2015 : 13:33:08
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quote:
Originally posted by ZLM
The GQ-4X works on this chip.
You need to de-solder the chip and then put it on the programmer for reading. When de-soldering chip, try to avoid overheat it for long time. Also, do not break the pin from the chip body.
Your chip is data is more than 25 years. In general, the EPROM data retention time will be around 10-15 years. For your chip, I can only say "Good Luck!" to read the data 100% correct.
Thank you.
I have ordered a 32 pin test clip with 15 cm ribbon cable and a 32 pin DIL plug.
I think I'll try reading the first chip contents while still installed in the board. It is a "cartridge" card with very few components other than the EPROM. Perhaps, because it will not be inserted into the mainboard, it will be independent enough to read.
The cartridge is still testing as "good", but I understand what you are saying about bit-degradation and background radiation erasing cells.
Finding a 32 pin test clip and cable took some time.
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Edited by - jwillis84 on 09/28/2015 14:04:39 |
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| Reply #3
ZLM
2945 Posts |
Posted - 10/01/2015 : 07:05:43
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No. The clip does not work.
The EPROM programming need a 12.7V voltage. That may damage your target board if you do it that way.
The UV type EPROM programming need to be programmed off the circuit. |
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| Reply #4
jwillis84
USA
5 Posts |
Posted - 10/02/2015 : 10:11:45
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quote:
Originally posted by ZLM
No. The clip does not work.
The EPROM programming need a 12.7V voltage. That may damage your target board if you do it that way.
The UV type EPROM programming need to be programmed off the circuit.
Thank you for the Warning.
I understand. The Vpp voltage could damage the circuit the EPROM is in if it were programmed while it were still inserted into the board.
I only planned to "Copy" the EPROM while it is still in the board. So I would assume only Vcc voltage would be applied.
But I see your point, if the programmer is used for read/only it may still use Vpp to detect the chip type, so this is not a safe procedure.
I'll consider my options.. I am concerned that desoldering could damage the contents of the EPROM. I can replace the EPROM. I can't replace the contents of the EPROM if I do not have a copy. |
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Please help me select an EPROM reader
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