I have an ST380021A drive (80GB IDE parallel interface).

Won't spin.

It has an IC that looks like the smoke escaped.

I'm not sure the purpose of this IC. The first line looks like it reads 2P102 but I can't be sure of that, and cannot make-out the 2nd line.

Can anyone tell me the function of this chip, and whether replacing it will likely yield another set of smoke signals (problem is elsewhere), or any other tips?

TIA.

FDFS2P102A.

It is a DC-DC converter. +5V/-5V. Preamplifier may be shorted.

Check the resistance between -5V/GND with PCB isolated and connected.

Thank you for your help. LOL, I can see where this is going (fried preamp).

But just so I can learn something, steps are...

Isolate from heads and motor or just heads? And then check for resistance between pin x and pin y (do you know the pin #'s, I looked at the datasheet and it wasn't immediately apparent). And I do this while the PCB is under power?

I'm pretty sure this one is beyond me but I feel like I could learn something in the meantime. I would like to see how to determine if a preamp is bad.

Remove the burnt ic first.
I think colanco is saying do the resistance measurement with the pcb fitted to the hda and then the same measurement with the pcb removed. No power required.

I guess if you have a 2nd good working drive you could just measure between ground and all the pins and then compare readings between the two drive hda's without the pcb.

Only isolate heads


pin 5 or 6 chip is -5V (GND anywhere screw)



Without power.

If you connect PCB and the resistance near 0, possibly PREAMP is shorted.

If there is no difference, change component and with PCB isolated, power on.

If everything ok connect the PCB to the disk and should work.

+1

Before attaching the PCB back to disk, POWER OFF

Again, thanks for the help.

I removed the IC and tested between a ground and 5/6 and it appears 0/shorted with the board off the drive. Am I looking for a very low resistance because I doubt my meter is accurate enough.

I have compiled a list of HDD ICs here:
http://www.users.on.net/~fzabkar/HDD/HD ... _Regs.html

Strictly speaking, the FDFS2P102A is a Schottky diode and MOSFET in a single package. The DC-DC converter consists of this IC plus the PWM controller inside the SH6950D motor controller.

Here is the datasheet:
http://www.farnell.com/datasheets/1506466.pdf

The pins you should be measuring are 1 & 2, not 5 & 6. Pins 5 & 6 will always be connected to ground via the 100 coil. You can snip pins 1 & 2 with flush cutters to isolate the IC.

The following article has examples of negative switchmode regulators:

Tutorial - Linear and Switchmode Regulators used in HDDs:
http://www.hddoracle.com/viewtopic.php?f=59&t=231&p=596

_________________
A backup a day keeps DR away.

Yes, 1/2 pin are correct. Thank you fzabkar

Once again thanks for the advice.

I measured with the board removed from the drive and get some super-high reading, it may as well be open.

I measured with the board installed on the drive and get about 185 ohms.

Does that make any sense?

Oh and BTW the IC was removed for these tests, and no power applied to the board, either.

IMHO, Preamp fried, but if you have another chip, change and test the board on the HDD (the risk is minimal for data). If it burns again, bad preamp.

ISTM that your preamp is testing OK.

_________________
A backup a day keeps DR away.

I accept the diagnosis of fzabkar.

Therefore, change chip or PCB.

ISTR that I saw a similar resistance in another thread. At that time I had the same misgivings as you, but the preamp in that case turned out to be OK.

_________________
A backup a day keeps DR away.

Alright, I'll give it a shot tomorrow and let you guys know.

Well I got a new IC on there but the drive won't spin-up, but the chip hasn't gone super-nova either.

I wonder if the drive was injured by the 5v power supply and other stuff is bad, too. So then the next question is whether I should try a different board (which I don't have and would cost $50 on ePay).

I have pretty similar boards (like the one from which I just borrowed the IC). I was curious about trying that board just to see if the drive would spin-up, but don't want to hurt chances of getting the data back by hurting the heads (for example).

If board from same model - you could try without worries. (I have same board for $10)