Electronics > Repair

Weller WMD-3 M27C256B dump needed

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fzabkar:
ISTM that, as Vcc increases, the bad bits switch from 0 to 1, not the other way around. I don't know if this is repeated over the entire address space.

ROM.bin


--- Code: ---Offset(h) 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F

00007E00  01 FF 01 FF 03 FF 03 FF 09 FF 01 FF 0B FF 0B FF
00007E10  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
00007E20  E7 E7 F7 FF FF FF FF FF EF E7 EF EF FF FF FF FF
00007E30  F7 F7 F7 F7 FF FF FF FF FF E7 FF E7 FF FF FF E7
00007E40  01 FF 01 4B FF FF FF FF FF FF 01 01 FF FF FF FF
--- End code ---

ROM-VCC5_5.bin


--- Code: ---Offset(h) 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F

00007E00  01 FF 01 FF 03 FF 03 FF 09 FF 01 FF 0B FF 0B FF
00007E10  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
00007E20  E7 E7 FF FF FF FF FF FF FF E7 EF FF FF FF FF FF
00007E30  F7 F7 FF F7 FF FF FF FF FF E7 FF E7 FF FF FF E7
00007E40  01 FF 01 FB FF FF FF FF FF FF 01 03 FF FF FF FF
--- End code ---


ROM-VCC6_5.bin


--- Code: ---Offset(h) 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F

00007E00  01 FF 01 FF 03 FF 03 FF 09 FF 01 FF 0B FF 0B FF
00007E10  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
00007E20  F7 E7 FF FF FF FF FF FF FF EF FF FF FF FF FF FF
00007E30  FF F7 FF F7 FF FF FF FF FF E7 FF E7 FF FF FF F7
00007E40  41 FF 01 FF FF FF FF FF FF FF 01 4B FF FF FF FF
--- End code ---

wraper:

--- Quote from: fzabkar on December 29, 2020, 07:51:42 pm ---ISTM that, as Vcc increases, the bad bits switch from 0 to 1, not the other way around. I don't know if this is repeated over the entire address space.

--- End quote ---
Then chip should be read at decreased voltage. Say 4V, or even less.

wraper:

--- Quote from: Hooligan on December 29, 2020, 06:55:14 pm ---Tried to play with Vcc, but no success, everytime get a different data. Made bitwise OR on dumps with same Vcc, the result is attached.

--- End quote ---
But why you only tried increasing the voltage?

Hooligan:
Do you mean I should lower voltage or try to heat the IC?

wraper:

--- Quote from: Hooligan on December 29, 2020, 08:30:58 pm ---Do you mean I should lower voltage or try to heat the IC?

--- End quote ---
Lower the voltage, put into freezer. Try both ways.

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