Atari 1040 STE disk drive problem

[naujoks]

I have a problem with the disk drive in my 1040 STE.

On startup, it spins up alright, but the head just jerks back and forth 1mm.

When I move the head towards the inside by hand, on startup the drive moves it to the outside but it doesn't move from there. I cleaned and relubricated the spiral thingy.

There are two caps on the PCB which looked dodgy and I replaced those.

While playing around with it, the drive suddenly was working and I thought all's well, only for it to stop working again next time I started the computer.

The drive is a Sony MFD110-003.

I put in a known working drive from a different STE, and that's working just fine.

Any ideas what I could try?

[Zogging Hell]

Have you cleaned the drive head? Sounds like it is searching for the initial tracks and not finding them. It could be the heads got temporarily cleared by something when it worked and then picked up some more crud from one of your disks. Other than that there are quite a number of potential problems, the motor could be on its last legs or the track the head moves along could also need greasing/ lubricating. The other thing to check would be your ST PSU as this could be not giving out the right voltages, which seem to impact the disk drive quite early on, the other drive you tried might use slightly less power and therefore not be as impacted.

[naujoks]

I tried the other STE's drive in the one I'm having difficulties with, but I also tried the faulty disk drive in the working STE, where the drive also didn't work.

It's strange though: when the computer has been on for 15 minutes or so, the disk drive is working without any problems.

Which part needs time to "warm up" and why?

[Zogging Hell]

Perhaps caps or a faulty chip perhaps or it could be something as simple as some grease or dirt, which becomes more fluid at a higher temperature. Do you have any 'freeze' spray? As a second thought it could be a simple cold solder joint. Might be worth reflowing any that look suspicious.

[naujoks]

I put the drive on top of my PC, where it's being warmed up to about 40 degrees.

I put the drive in the STE and it starts right away. It's all SMD parts on the board, apart from the connectors. I'll see if I can see anything suspicious.