hello all ;

i have a wd2500bevt-22zct0 that doesn't spin up at all .
pcb# 2060-701499-000 rev a
pcb printed #2061-701449-500 AF

pcb has no burn spots and looks totally normal.

i have a donor drive (that has some problems reading SA , drive spins but not detected at all)
pcb# 2060-701499-000 rev a
pcb printed #2061-701449-500 AF

tried just to swap the pcbs , but the patient drive doesn't spin either (it produces a tiny sounds of ticking - not related to head assembly as it donut move at all)

did some multimeter measures on the two pcbs and found that :

element working PCB non-working PCB

c25 117 OHM 24 ohm
c26 117 OHM 24 ohm
c24 117 OHM 24 ohm
c4 111 ohm 24 ohm
c1 110 Ohm shorted
c56 75 Ohm 24 Ohm
c57 75 Ohm 24 Ohm
c61 75 Ohm 24 Ohm
d1 76 Ohm 23 Ohm
c70 123 ohm 24ohm
c21 117 ohm 24ohm

any way to repair the broken pcb using the working pcb components ? to avoid the embended flash transfer ?

thank you very much

What is the resistance between the +1.2V test point and GND? Is it 24 ohm?

What is the resistance between the +3.3V test point and GND?

What voltages do you measure at these points? Don't bother powering up the board if the +3.3V supply is shorted.

_________________
A backup a day keeps DR away.

thank you for your responds ..

What is the resistance between the +1.2V test point and GND? Is it 24 ohm?
YES 24 ohm on the broken pcb and 84ohm on the working one

What is the resistance between the +3.3V test point and GND?
broken pcb reading 7.55 K OHM and working pcb reading 9.64 K OHM


What voltages do you measure at these points? Don't bother powering up the board if the +3.3V supply is shorted.
3V reading 3.25 V , 1V reading 0

I suspect that the MCU is responsible for the low resistance reading on the Vcore supply. It also looks like the SMOOTH chip may be bad.

I would check the voltage at the anode of D2. I believe it is probably the negative supply (Vneg) for the preamp.

I would also confirm the voltages at Q1. I believe this is the Vio supply.

There are also two capacitors (C6 and C14) that look interesting, as well as R12 (1 ohm resistor). Could you measure the voltages at these points?

Could you also measure pins 2 - 12 at the preamp connector? I suspect that 10 and 12 may be the VCM pins, but the others are probably the supply voltages.

If you could compare the voltages between your two PCBs, then that would help a lot.

BTW, have you actually observed whether the heads are parked on the ramp, and whether the motor spins by hand?

_________________
A backup a day keeps DR away.

True that.

Also, another simple "spinning" test is to test the presumably "bad" PCB on your donor drive. Does the donor spin?

_________________
Hard Disk Drive (HDD), Solid State Drive (SSD, SATA, NVMe, etc), USB Flash Drive and RAID Data Recovery Specialist in Massachusetts

Presumably bad?

Of course the original PCB is bad. It has no Vcore, assuming the OP's measurements are correct.

_________________
A backup a day keeps DR away.

The suggestion is for any WD drive on a more general basis, not necesarily for this case alone.

Did not read all those measurements.

_________________
Hard Disk Drive (HDD), Solid State Drive (SSD, SATA, NVMe, etc), USB Flash Drive and RAID Data Recovery Specialist in Massachusetts

I'm a little confused by the OP's explanation. He said that the heads don't move. AIUI, the WD2500BEVT has a loading ramp. If the OP had looked under the cover, then surely he would have been able to see a stiction fault or spindle seizure. Anyway, if the drive doesn't spin, then why would the OP have bothered to say that the heads don't move?

My feeling is that the PCB may have failed while the drive was spinning. This could then have left the heads over the platters.

_________________
A backup a day keeps DR away.

thank you all again for your help ;

isolating the pre amp contacts will not make the spindle move at all , even on the working drive using the working pcb ...

i DID know that the heads didn't move yet ,without taking off the cover .

having the pre amp shorted is the thing am afraid of ....

donor drive doesn't spin using the paicent PCB.

the measurments are :

Q1 : from left to right
5 **6.75** 4.25 volts

d2 : 0.14 V on the Vneg leg

L1: 0 v (shorted with GND)
c6 : from top to bottom 4.10 ***** 0V
c14:from left to right 4.6V *** 0 v
r12: 0 V from two sides


thank you again for helping ...

on the working pcb , readings are

Q1 : from left to right
4 **5.10 ***3.25 volts

d2 : 3.05 V on the Vneg leg

L1: 1.4 v
c6 : from top to bottom 8.2 ***** 0V
c14:from left to right 4.75V *** 0 v
r12: 0 V from two sides

yes sir ;

i used this trick as u suggested , but even the donor drive wonut spin with it's original working pcb !

The readings for Q1 look wrong. The centre pin should be connected to the +5V SATA pins. Either your PSU is BAD or your multimeter is flaky.

L1 cannot be shorted to ground. You previously measured 24 ohms. Instead it appears that the SMOOTH chip is not generating the PWM pulses for the Vcore supply.

Vneg is also generated by the SMOOTH chip. Once again it appears that the PWM pulses aren't there.

Therefore ISTM that your motor controller is dead.

_________________
A backup a day keeps DR away.

Do you mean -3.05V for Vneg?

If the voltage on C6 is correct, then maybe it's a charge pump capacitor. This would then support my previous diagnosis that the SMOOTH chip is dead, ie a voltage of 4V would imply that the charge pump on your original PCB is not working.

The voltage of 1.4V seems high. AFAICT it should be +1.2V. Is that your multimeter playing up?

_________________
A backup a day keeps DR away.

sorry , my bad
patient pcb Q1 readings: from left to right
3.95 **5.12 ***3.22 volts

and once again , am sorry
L1 is not shorted

ISTM that you won't be able to retrieve your ROM from the patient PCB. Even if you could replace the SMOOTH chip, it could still be that the MCU is dead.

As for a dead preamp, if you could measure the voltages at the preamp connector, then we could locate its supply pins. Then we could test for shorts right at the HSA.

_________________
A backup a day keeps DR away.

Sounds like you need to get a fully working donor or known good PCB and try again. In DR, time is money and all this useless testing is a serious waste of time in my opinion.

Do you mean -3.05V for Vneg?

yes ... working pcb reading -3.05 v while broken one reading +0.12v V

smooth chip is bad then ... will look for a soldering pro < and see if he can move the smooth chip from one to another ...


thank you , and will keep u updated .

I still think the MCU is also dead. A reading of 24 ohms is much lower than your donor PCB. I think it is unlikely that this low reading is due to the SMOOTH chip. The other thing that leads me to suspect the MCU is your resistance reading for C1.

_________________
A backup a day keeps DR away.