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tester272001 · Deadharddrive regular +1 Joined: 08 Jan 2008 Posts: 37

BTW - I scraped the top of that FW503 and it had burned carbon! I check the one on the new board and it was fine. You may have nailed that DC to DC converter! According to the datasheet it has an internal diode.
That measures ok from pin1 to 8 but the resistance from pins 3 to 4 and 4 to 5 are way low. like 16ohms and the good board is over 1k. It looks like a good choice to swap out. Hopefully nothing else got fried. I am going to go rooting thru some old HDD and see if I have another FW503 on one of them. Just in case it burns again. Wink

tester272001 · Deadharddrive regular +1 Joined: 08 Jan 2008 Posts: 37

fzabkar, hopefully sunndreamspace was just joking with you and not being nasty. I will say that its great to have someone try to help. I have helped many people ove the net with lots of problems and its very satisfying to be able to open someones eyes and show them the way. Like the old saying, if you give a man a fish he will eat today, teach a man to fish he will eat all his life. Very Happy

tester272001 · Deadharddrive regular +1 Joined: 08 Jan 2008 Posts: 37

Well I checked some voltages on the known good board and the IC that is fried normally carries 5V+/- and the TVR diode on the other side is measuring +12V. So the 5volt line shorted in the FW503 chip. I am planning an attempt to desolder that chip and swap the one from the good PCB. The leads on that chip are large enough I can prob. use a normal iron that is nice and clean and some copper braid. Wish me luck. Exclamation

tester272001 · Deadharddrive regular +1 Joined: 08 Jan 2008 Posts: 37

The saga continues. I transferred the 503 chip from the doner board to the old PCB and the voltages look good. The HDD does not spin up. I measured zero volts on all of the four pins that feed the drive motor. Do you think swapping the SMOOTH chip will do the trick? Am I wasting my time or you think it could work ??? Sad

fzabkar · Deadharddrive regular +3 Joined: 02 Apr 2010 Posts: 210

Sorry, I've been AWOL. Maybe my reaction was a bit excessive, but if you watch the HDD Guru forums, you'll understand why. That said, kudos to anyone who genuinely wishes to help you.

Anyway, before going any further, I would first determine whether the FW503 chip is supplying the preamp inside the HDA with a negative rail. You should be able to trace the anode of the flywheel diode to the preamp connector. If the preamp is damaged, then you will just be wasting money on a board swap. In any case, I would not troubleshoot the PCB while it is connected to the HDA.

AIUI, the SMOOTH chip controls the various switchmode regulators. These provide power to the MCU core, MCU I/O, and the preamp. If the SMOOTH chip is dead, or not receiving its own supply rail(s), then I suspect that the DC-DC converters will be inoperative.

The outputs for the positive converters would be at one end of the coil, or the cathode of the flywheel diode.

fzabkar · Deadharddrive regular +3 Joined: 02 Apr 2010 Posts: 210

Sorry, I missed your latest posts, so some of my suggestions may not apply.

If you are at the point where you are considering swapping the SMOOTH chip, then perhaps you have reached the limits of DIY repair ???

Anyway, it appears that the preamp is not shorted, which is something the DR guys will often caution you about.

Good luck.

tester272001 · Deadharddrive regular +1 Joined: 08 Jan 2008 Posts: 37

Thanks once again for a lead. In my original post I said, the original pcb was a K4FYA. I replaced with PCB L6FYA. Would the two digit number in the front portion of that make a significant difference ? As I said the drive spins and tries to initialize, clicks like 10-15 times and then stops. How do I identify the flyback diode that leads to the preamp ? From the photo I uploaded where about on the board would that be ? I spent a good bit scanning the board with high magnification lense but I see very few diodes and mostly caps and resistors Sad

I located the VCM+ and - point if that gets me anywhere. My old eyes are not getting any better LOL.

tester272001 · Deadharddrive regular +1 Joined: 08 Jan 2008 Posts: 37

OK so the drive spinds and clicks. The preamp is presumably GOOD? Is my problem then perhaps the firmware is just not exactly for the drive I have vs. the PCB I bought ?

fzabkar · Deadharddrive regular +3 Joined: 02 Apr 2010 Posts: 210

The FW503 part is a FETKY, ie a MOSFET chopper and flywheel diode in the one package. You can see the layout of the discrete components in the application circuit in the datasheet for the L7250 SMOOTH chip. In that case there is a -4V DC-DC converter. In fact your board has a -5V test point below the FW503 chip, so there is no need to go looking for the flywheel diode.

I don't know whether your preamp is good, but at least it doesn't appear to be shorted, otherwise it would possibly have damaged your replacement board. In fact, I've lost track of this thread. You did in fact mention in your opening post that your drive clicked, so that should have settled this question.

As for the other supplies, I would use the L7250 datasheet to locate those. You could also test for the presence of a Vdd supply at the SDRAM chip:

HY57V641620HGT-6, Hynix, 64Mb SDRAM, 1M x 4Bank x16:
http://www.datasheetarchive.com/pdf-datasheets/Datasheets-13/DSA-254659.pdf

There is a +3.3V test point below the RAM.

There is also an active low POR (power on reset) pin near Q400 (5139 marking).

As for your question re ROM data, I have no idea. That's something that the supplier of your replacement board should be able to help you with.

Maybe this thread will help:
http://forum.hddguru.com/howto-how-replace-maxtor-calypso-iii-board-t5977.html

I'd also check Q501 near the power connector. This transistor is often bypassed by the DR guys. I suspect that it switches the +5V supply.

BTW, I have tired old eyes, too. :-)