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| Powerbook 140 scsi hard disk failure |
Posted by: dchang on 2017-12-01 09:20:16
Just a stab in the dark, I got a PB140 the other day (in an AS-IS basis) and surprisingly it works.
But it won't boot from the hard drive.
So I took it apart and poked around (after watching a few videos online). From what I can tell
power is reaching the actuator arm and spindle (when I use a screwdriver to move the spindle in
the centre) it seems to jump a bit (when connected with power). If I'm not mistaken, then
that means that the PCB on the disk isn't sending commands to the disk?
So the disk isn't spinning at startup. I'm trying to figure out if it's the PCB or the motor.
If power is provided by way of the scsi connector (on the PCB), and power flows to the actuator arm
(I'm assuming given my observation), can I assume that the PCB is receiving power and functioning?
Is there any other indicator that a PCB is functioning? There is no indicator light on the PCB.
By the way it's a Quantum Daytona 341s.
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Posted by: youjuoufudtgd on 2017-12-01 10:01:11
Although it would be interesting to figure this out, it might be a better use of your time to just get another hard drive.
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Posted by: dchang on 2017-12-01 10:03:32
Another thing, are there references to pinouts for these SCSI drives?
I found this: http://vintagemacmuseum.com/reading-powerbook-2-5-scsi-hard-drives/
But it's confusing about the number of pins. The PB140 has got a 40 pin cable.
4 pins on the disk are not connected. So an adapter for 54 pins to 50 pins SCSI suggests otherwise.
I've also got a PB165 but it's got a full width cable (50 pins). The cable (50 pin) fits the drive fine.
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Posted by: dchang on 2017-12-01 10:14:34
Hi Parrotgeek1,
Yeah, I think a better strategy is replacing the SCSI drives with CF or SD flash drives.
Something I'd like to do eventually.
But I watched video online about HD repair and watched a guy remove the PCB
and check continuity between PWR and GND pins (on the connectors) and then
proceed to check continuity on the diodes. If I understand it correctly, if there isn't
resistance between PWR and GND (and the multimeter beeps) then there's a short.
Diodes protects against a reverse polarity charge. So if a diode gets burnt then
a charge saturated the diode (shorting it). So by removing it, the technician was
able to get the PCB working.
That's what I think. Anyway, as mentioned, I'm not sure about the pinouts on these
drives. So I don't know what I'm checking. Only Vcc/Vcc pins and GND/GND pins
should show continuity (but I'm not sure which pin is which).
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Posted by: dchang on 2017-12-03 06:01:30
I found the Powerbook 140 and 170 Developers Note.
It's a 30 pin cable.
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