Faulty Apple Lisa 2/10 Drive - Problem persists

No worries, it was worth a shot and I appreciate your help. I've actually learnt quite a bit so that is no bad thing. I think I'll consign this to the "might look at again some time in the future" pile. I'm sure everybody has such piles in their workshop. Mine seems to keeps growing (-: Terry ----- Original Message ----- From: "Tony Duell" <ard at p850ug1.demon.co.uk> To: <cctalk at classiccmp.org> Sent: Thursday, March 03, 2011 8:05 PM Subject: Re: Faulty Apple Lisa 2/10 Drive - Problem persists >> >> 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 > > >> 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 >