I have a Western Digital WD30EZRX that was inside of a My Book Essential external drive that stopped working awhile back. I took the drive out of the enclosure and tried hooking it up directly to my computer, but it still does not power up. I don't hear any noises, clicks, or anything. Looking at the controller PCB, I can't find any obvious signs of burnt components. I've contemplated replacing the controller PCB with an equivalent board (with the necessary bios chip swap) from an online company, but before I burn up $50 I'm hoping someone here can increase my confidence in such a swap. Is there any other testing I can do to confirm if the internals of the drive are bad? I'm handy with a multimeter, so if any probing/testing can be done I'm confident I can do that with a little direction on where and what to measure.

Can you upload a detailed photo of the component side of the PCB?

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A backup a day keeps DR away.

Measure the resistances of the following 4 components:
http://www.users.on.net/~fzabkar/HDD/bi ... diodes.jpg

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A backup a day keeps DR away.

R64 = 1.05 ohms
D4 = 205.7 kohms
R67 = 1.06 ohms
D3 = 238.6 kohms

Is it normal that it takes a bit for the resistance reading to stabilize for each component?

Your readings are OK, and yes, a little settling time is normal.

Could you now measure the voltages at V1, V2, and Vneg? These will be the Vcore and Vio supplies for the MCU, SDRAM, and EEPROM, plus the negative supply for the preamp.

You could also measure the voltages across the associated capacitors?

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A backup a day keeps DR away.

V1 = 1.1V (adjacent capacitor also 1.1V)
V2 = 2.6V (adjacent capacitor also 2.6V)
Vneg = .037V
Four capacitors on the left = 12V

I measured voltage across the capacitors, but used a bolt hole ring for ground probe when measuring V1, V2, and Vneg.

That's telling us that the SMOOTH motor controller is at least partially functional.

The negative supply is under the control of the Marvell MCU (the MCU switches it on and off), so it may be that the MCU is faulty. In another thread, the OP measured Vneg soon after the drive was powered up. He found that the voltage went to -5V and then dropped back to 0V after a short while. If you PCB does this, then this would suggest that the MCU is alive. To this end I would install the PCB on the drive and measure the voltage at the point marked "B2" on the other side of the board. I believe this is the Vneg supply, but I'm not certain. The points marked A and B would be the +5V and -5V supplies.

One other thing to do would be to clean the oxidisation from the J1 contacts by gently rubbing them with a soft white pencil eraser.

Still one more thing to investigate would be whether the drive is configured to Power Up In Standby (PUIS), but in this case it should still appear in your computer's BIOS, albeit with a blank model number.

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A backup a day keeps DR away.

I cleaned the contacts, reinstalled the board, and looked for a point marked B2, but the one that looks like its directly on the other side of the pad you marked in the picture was labeled E13. I put my negative lead on the hard drive chassis and the positive on this pad. After connecting the power I'm seeing a peak of about -2.5V that blips twice and then back to zero almost immediately. While I was testing it, I did notice something I hadn't before. When I plug in the power there is a very faint "tick, tick, tick" that happens twice, possibly in time with the voltages. It sounds like its coming from inside the drive and not from the board.

You marked points A and B, but I'm not sure what you want me to do with them. I tried finding their corresponding pads on the other side, but nothing marked seemed to line up. As far as the PUIS test, I haven't tried it yet but I assume it would have to be hooked up directly to the motherboard through a SATA port to possibly work? I've been using a USB universal hard drive adaptor (Apricorn Drivewire) to do all this testing.

The ticking sound is probably indicative of stiction (heads stuck to platters) or a seized spindle motor.

Can you measure voltage pulses at the motor terminals? What are the resistances between the motor terminals (3 phases plus common)? The phase-to-phase resistance should be around 2 ohms while the phase-to-common resistance should be around 1 ohm.

In short, the PCB is probably OK.

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A backup a day keeps DR away.

Voltages at the motor terminals are as follows:
MIN/MAX
1) -.114V/.629V
2) -.165V/.461V
3) -.089V/.388V
4) -.077V/.601V

Resistances between the motor terminals were around 1.14 ohms, and between the chassis and pads was 1.14 ohms for the first one then .9 ohms for the other three.

Can you measure the resistances between PCB ground and each of the PCB pads with the PCB removed from the drive?

Can you then measure the resistances between the metal case of the drive and each of the terminals on the motor, also with the PCB removed from the drive?

This will tell us if any of the MOSFET drivers within the SMOOTH chip are shorted to ground, or if any motor winding is shorted to the body.

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A backup a day keeps DR away.

The resistances between the hard drive chassis and motor pads are all coming up zero with the PCB removed.

I'm not sure exactly what you mean by PCB ground and PCB pads, but I assumed it was between the metal rings around the screw holes for the PCB ground and the PCB pads to be the four prongs that connect to the motor pads when the PCB is installed. If thats the case, then the pads show 1.97 kohms, 1.97 kohms, 1.02 kohms, and 1.93 kohms.

Unless your motor is some odd new design, ISTM that one or more of the motor windings are shorted to the chassis. :-(

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A backup a day keeps DR away.

Maybe I worded that wrong....I think I should have said they're all testing open instead of zero.

Sorry, I can't make sense of your readings.

This is a typical configuration where the motor has 4 terminals:



The resistance between Common and each of A, B, and C should be half the resistance between any pair of A, B, C.

No terminal should have a low resistance path to ground (aka "chassis").

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A backup a day keeps DR away.