A1:4ohmn 0mV, A2:43.1 Kohm, B1:12.3 Kohm, B2 was 13.4. Not picking up any voltage on my multimeter but it is pretty cheap... Maybe i'll try my voltage injector?

When you measure resistance, no power should be applied.

When you measure voltage, the board should be powered on (and not installed on the drive).

Sorry if I'm stating the obvious.

It does look like A1 is shorted.

Is B2 13.4 ohms or 13.4K?

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A backup a day keeps DR away.

Kohms for B2. It would be odd for A1 to be shorted since this pcb works fine on the donor drive right? Ok i'll power it on. I figured the multimeter applied some current to measure but I guess its not enough.

A1 would be shorted when the PCB is on the drive, and OK when off the drive. That points to the short being inside the drive, not on the PCB.

In other words, your preamp is dead.

_________________
A backup a day keeps DR away.

Gotcha! Yep it was the same on and off. Ok. So I guess the next thing I need to do is block the contacts with a card and then see if the motor spins or do you think that kind of clears things up on its own. Thanks for all the help this is really educational I'm enjoying it.

Forgot to mention I did the business card blocking test and it spun up so it definitely seems to be the spindle. I'll be proceeding with a replacement once I get my laminar flow hood assembled. I have several old drives i'm going to practice on first.

HDD from inside: Hard Drive Main parts:
https://hddscan.com/doc/HDD_from_inside.html

_________________
A backup a day keeps DR away.

A timely reminder that once you open the drive body a good number of DR labs will not take the drive and those that are prepared to charge a considerably higher for recovery or an additional open drive fee.

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Data Recovery Services in the UK.
https://www.usbrecovery.co.uk/

Good to know. I'm trying to figure out what size comb to get for this drive. I'm thinking a #103 but I can't find any documentation talking about the proper comb for toshiba p300 3tb head replacement. Anyone got any tips on how to find the right size comb? I know its 3/6 ratio. I see mentions of #103 and #203 supporting inner parked and outer parked heads. Does inner park mean the heads park at the spindle and outer meaning they park away from the disks(the opposite)?
Here is the listing I got the info from. https://www.ebay.com/itm/272054907798?h ... SwAKxWU5n1

I have a h14 2'x3' filter on the way and will be setting up a flow hood this week to do the swap.

Thanks!!