I see 0A29582 on both PCBs???

_________________
A backup a day keeps DR away.

@ op
You are from Syria?
Where are you living now?
If you living in Egypt now, I can help you for free.
Good luck

0A29374/0A29375 appear to be motor controller ICs, not PCB part numbers.

_________________
A backup a day keeps DR away.

fzabkar,
Yes, sorry, I looked in the wrong column.
F 0A29582 01
F 0A29526 01

I stop doing DR. Losses and age. There is no point in continuing to work. As soon as I check all the donors, I will lay out the tables in the sale of large lots.
You'll need them, but I won't.

I live in syria damascus
thank you very much for your offer

fzabkar,

on the both patientand donor PCB
v1 = 1.74
v2 = 1.74
v3 = 1.74
V+ = +5
V- = -5

Measurement for resistance for V+ and V- is between ground and the V (V+ or V-)
correct?

Yes.

As for your voltages, I would have expected to see +3.3V somewhere. :?

_________________
A backup a day keeps DR away.

I think you may be using the wrong ground reference. When measuring V1, V2 and V3, your black probe should be on ground, eg a screw hole.

_________________
A backup a day keeps DR away.

in the two PCBs resistance are:
R5 = 20

off drive
V+= 1900
V- = 110

on drive
V+ = 1500
V- = 20

The resistance of R5 should be 0.47 ohms. :?

Resistance should be measured between the ends of the resistor, and it should be done with power switched off.

The resistances at V+ and V- should be measured between ground and each test point.

If you touch the two probes together, do you measure 0.0 ohms resistance?

_________________
A backup a day keeps DR away.

the problem is with the millimeter I used, Its not precise
the reading did not changed after connecting the two prop outside the PCB

If your multimeter is showing 20 ohms when the two probes are touching each other, then this would imply that the V- supply, which is also measuring 20 ohms, is shorted inside your preamp.

You can check whether your probes are OK by removing one probe and then measuring the resistance of the remaining probe by inserting the probe tip into the multimeter. Do this for each probe.

You should also rotate the selector knob backwards and forwards to disturb any contact oxidisation.

_________________
A backup a day keeps DR away.

and that mean it is hopeless case?

Yes, it would appear that your drive is not a DIY candidate, but an accurate measurement would give me more confidence in my assessment.

_________________
A backup a day keeps DR away.

I will arrange to get these measurement in better multimeter

fzabkar,

I do the following test:

Put the donor PCB on the donor drive and measure the V- and it was near 80 ohm
I assume that mean confirming the V- shorted inside the patient preamp as you mention before.

If there was a bad preamp, it would start the motor while isolating the preamp.
Return the NVRAM to the new board, and check if you have already killed it.

so it may be more than one problem in this drive

fzabkar,

I do the following test:

Put the donor PCB on the donor drive and measure the V- and it was near 80 ohm
I assume that mean confirming the V- shorted inside the patient preamp as you mention before.

Please confirm.

Are you still using the "bad" multimeter?

_________________
A backup a day keeps DR away.