Strange EME-232 Floppy Drive Problem

[Crashedfiesta]

Hope this is OK as it's not CPC specifically.

I've got a PCW9512 which uses an EME-232V drive. I bought a CP/M disk but it didn't work so, on the assumption the disk was OK (it proved to be OK - see below) I assumed that the drive was out of kilter and needed calibrating.

I also changed all the caps because that's the camp I sit in.  

At some point during the calibration the drive died. It was properly dead with no signs of life. I tracked it down to one of the current protection devices (Q4) and after installing a - ahem - temporary fix, the disk would spin but there was no head movement.

After a lot of faffing I traced that fault to the transistor that sits between the legs of the stepper drive chip, located at Q6. I replaced it and, wonder of wonders, the head began to move again.

So I continued trying to calibrate the drive but with no luck. Either the drive would seek slowly and then I'd get three beeps and a white screen or, if I was lucky, I could get it seek repeatedly as if it was close and I'd get four beeps and a white screen. And then, while I was holding the drive and trying to twist the stepper motor by the tiniest of amounts, I got a couple of lines appearing on screen. Then a re-seek and a few more appeared. Long story short the disk booted to CP/M and I thought I'd cracked it.

But I hadn't. To cut this three week story down a bit more, I've reached the point where the thing will boot every time but ONLY if the drive is on its side. Doesn't matter which one, but if it's on its side then it will boot. It's not 100% and there is plenty of seeking that goes on but it does eventually boot every time.. The question is, why? Anyone got any ideas?

[Bryce]

Yes, it most likely has dry joints. Reflow the solder on the pins of every connector on the PCB and I'll bet the problem goes away.

Bryce.