Powerbook 140 scsi hard disk failure

[dchang]

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.

 

[youjuoufudtgd]

Although it would be interesting to figure this out, it might be a better use of your time to just get another hard drive. 

 

[dchang]

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.

 

[dchang]

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).

 

[dchang]

I found the Powerbook 140 and 170 Developers Note.

It's a 30 pin cable.