snipped-for-privacy@kpgpbhdw.com wrote: Probably nobody here can tell you "if TP3 has less than 2.0 volts on it, change R134 and the drive will then work".
The information you would need to know that is in the design documentation for that drive, which used to live at IBM and probably now lives at Hitachi, if it's even still around. It is probably not available at any price - if somebody at Hitachi spends more than a few seconds finding it and sending it to you, the value of their time has exceeded the worth of the drive.
What you *can* do is look for any obvious burnt components, open traces (use a magnifying glass if you need to), and like that. You can also look up the pinout of the 44-pin connector and find out which pins supply +5 V power to the drive. Make sure the laptop really is putting out +5 V on those pins.
Some of the ICs on the circuit board may be custom but there might be a standard one or two. Google the numbers on the chips; if you can find pinouts for a chip, make sure the power supply voltages are correct.
There may be some chips on the "underside" of the board, that you can't see unless you take the board off of the drive. There will be at least two cables leaving the board - one for the spindle motor and one for the read/write heads. Sometimes you can disconnect these before you remove the board, and sometimes you have to unscrew the board, lift up part way, disconnect cables, and then remove the board completely. (You might even find that one of these cables has popped loose on its own, and reseating it might help.)
You can probably test parts of the board when it is disconnected from the drive mechanisms, but not all the signals will be there. Part of it may shut down when it doesn't detect the spindle motor coils or the read/write heads, for instance. You can for sure look for burnt components, open traces, etc on the newly-visible side of the board.
Matt Roberds