3

I have an Amstrad CPC6128. I replaced and serviced the drive belt a few years ago, but now I am getting some disc errors. The drive is making noise but a few discs are reporting 'disc missing'. However, other discs continue to work as expected for read and write.

Sometimes I can 'cat' the files, but then the disc fails on subsequent access. I will take the drive apart if I need to, but I'd like some guidance as to probable cause.

4
  • 2
    _"I replaced and serviced the drive belt a few years ago" - how often have you used the computer since then? Feb 3 '20 at 20:28
  • Very little. It mostly lives in the attic. Feb 4 '20 at 6:46
  • 3
    There might be several reasons. The discs themselves may lose their magnetization. The head(s) of the drive may be dirty. The drive's electronic circuitry may fail because of age. ... Feb 4 '20 at 7:06
  • These would all cause read and write errors, but would they cause the drive to think the disc is missing? Feb 4 '20 at 21:18
6

'Disc missing' may indicate that the disk is not spinning fast enough, or the index hole sensor is not working properly.

The most likely cause is a bad belt. If the computer is left idle for long periods the belt tends to deform where it goes around the motor pulley. So even though you replaced the belt only 'a few years ago' it is the first thing you should look at.

Another possibility is that the motor is failing to maintain speed. This could be caused by worn brushes or calibration drift in the speed regulator, but if the drive has had little use this is unlikely.

The index hole sensor might have some foreign material (dust, cobwebs etc.) over the lens which is reducing the light level, or the LED might be getting tired. Check that the LED is glowing reasonably brightly and the sensor lens is clean.

2
  • All good ideas. Will disassemble and check. Feb 4 '20 at 18:30
  • I'm accepting the answer. Disc speed checks out at reliable 304 to 307 Rpm, within tolerances. Opened and cleaned drive, but didn't change belt or lubricate. 'Disc Missing' messages now replaced by read fails on some discs which are consistent, so probably bad or cheap media. Drive reliably reading known working discs. Apr 7 '20 at 10:02

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.