Hello, I am wondering if anyone knows a way to determine which pins on the HDA that connect to the preamp are the ground and +-5V pins using a multimeter? I understand how to test the pins using a multimeter if the pinout is known, but for many drives there isnt much posted on which pins are which. There has to be some way to determine this with a digital multimeter?

thanks to anyone that can help!

A dmm will not help you alone.
You need more electrical knowledge, or someone's others help....

Janos

Thanks Janos. What else would i need to know? How do people figure these things out?

The ground pin must be "grounded" to something, right?

Upload a detailed photo of your PCB.

The ground pin would connect to the ground pin at the external power connector.

Here are the pinouts:

http://pinouts.ru/Power/sata-power_pinout.shtml

http://pinouts.ru/Power/BigPower_pinout.shtml

AIUI, the negative supply rail (-3V ?) is generated by an onboard switchmode regulator driven from the motor controller chip (eg SMOOTH). You could probably check for continuity between the 20-pin (?) HDA connector and the various coils on the PCB.

The heavier copper traces would be the most likely suspects, although two of them would be for the voice coil.

It is a little hard to explain for you, because it is in my bood maybe.
I am doing electronic repairing since my young (age 7-8) years.
If i see any pcb (not only hdd) i can recognize the pins or at least the pin cathegory (like power, data, address, controll, and so on...)
You need skills and knowledge.

You can easily find the groung pin (on good preamp case), becase it has 0 ohm to the next screw hole of the HDA.
(If the preamp is short, the GND and the VCC can be shorted, and you will see shorts on more pins...)

Janos

If the preamp is shorted, you can still remove the pcb and look for continuity between the power connector's ground and the preamp connection pads on the pcb.

Thanks guys, this is some good information. Basically, what I am trying to figure out is a "generic method" for finding a ground pin on any hda where the preamp is functioning normally and is not shorted out.

I figure if i can find which pin is ground, it is then easy to find the +5V and -5V pin using the multimeter.

Then, I can test for shorted preamps on drives with the same hda pin out.

So, this makes sense, trace the ground pins on the pcb connector to the contacts for the hda.

Other option is to use the multimeter to find a 0 ohm reading from a pin and a screwhole on the hda? Or was this a joke my mr. janos?

No, this was not a joke.
You can you any screw in the HDA, because all are GND.
The same on PCB.

Janos