2 Mar
2011
2 Mar
'11
11:05 p.m.
Some more progress but not good news...
Unfortunately replacing those caps and the TA7259 IC hasn't made any
difference to the 400k drives. The symptom (motor refuses to start when the
It is, unfortunately, very hard to diagnose faults remotely, particularly
on a device that I have never seen...
spindle is in a certain position) is still the same in
both. I don't have a
circuit diagram and it may be that there are some other bits and pieces
there, compared to later Sony drives.
I suppoe you could always reverse-engineer the drive. It can't be _that_
complicated.
In one of the drives, if the spindle is in a position where the motor
starts, it will read disks...but not well. It's very slow to load things.
I imagine there are lots of retries, maybe because the spindle isn't
spinning at the speed it should. In the second drive, even when the motor
does rotate, it does not load programs. It could be that this second
(rather more tattered) drive has more than one issue.
Oh well... it was worth a shot. Much obliged for the help, Tony and others.
I'm not sure how further I can go with it.
Anyone have any other ideas as to what might cause this problem? Maybe the
motor windings themselves are just shot.
I think it's very unlikely to be the windings. Didn;t we check that there
was roughtly teh same resistance between each piar of potor output pins
onthe vtornller IC anyeay?
My guess (and it's only a guess) is that it's one of the hall-effect
drvicces./ These are the little things with 4 connections at the edge of
the motor can its;elf. The body of the drvice is inside the motor. They
are labelled H1, H2 and H3 on the PCB I susepct
I think you will ahve to dismantle the motor can next. There are 2
flexible PCB tails ('flexiprints') coming out of thit. The top one -- the
one futhest from the PCB -- thet comes out of the can almost straingth
towards the left side of the drive is the FG (speed sensing) coil. It's
soldered to a pin header with is soldered to the PCB. Desoler this header
from the PCB (no not work on the flexiprint, it is too
fragile). With
that free, bend up the tabs o nthe bottom and lift the housign off
complete with the FG coil. Lift out the rotor.
You cna now see the hall effect devices. I have no idea where you'll get
replacemetns,m but those are what I would change next.
-tony