CPC 6128 Floppy drive (EME-156) problem

[timovo]

Hi,


I've got one drive that doesn't seem to be reading disks. These disks work fine in another CPC's drive.
I wonder if anybody would have some ideas what to try next.
So, I'm simply trying cat -command which results disk spinning and head moving a few times
(same behaviour as I've had with another drive when it had a head alignment problem) but in the end
it gives the "Drive A: read fail, Retry, ignore or  Cancel".


Done so far:
- Changed the belt (it was broken) and cleaned the residue with IPA & cotton swaps
- Cleaned the drive head with IPA & cotton swap
- Checked the RPM -> it was ~306 so, I adjusted it to ~299.8rpm
- lubricated the rails
- Tried to change the head motor alignment (small change, cat, small change, cat ...) with no success
- Resoldered / flowed the solder joints in the drive PCB that seemed suspicious ... and even most of the one that seemed ok
- soldered wires on TP1 (and TP2) on the PCB and monitored with an old 10MHz scope while issuing cat command,
  repeated this several times and after each time slightly rotated the head stepper motor to change the alignment.
   --> no activity on the lines - lines stay at 2.6V... well, I can see the interference on the lines when the head motor is moving but that is all.
- removed the head assembly to verify that the wires from PCB to head seemed still to be attached to the head ok
- Tried another floppy drive in this CPC  6128 to be 100% sure that the problem is in the drive
  --> that another drive worked just fine
- Erased one floppy with a quite thorough magnet treatment (magnet from an old hard disk) and formatted it with MultiMark on this drive.
  Note: I loaded the multimark from drive B (Gotek) in case someone is wondering.
  --> Verification failed on in Multimark after it had formatted the floppy
  --> reading disk directory with cat also gave the same results as before

[Bryce]

You've pretty much covered everything there. The drive head may be broken.

Bryce.

[timovo]

Yes, I suppose you may be right...
Perhaps this would be a perfect opportunity to put an internal Gotek in this CPC.
-Timo

[Bryce]

You can send it to me for confirmation (or repair) if you like.

Bryce.

[timovo]

Thanks very much for your kind offer Bryce!
I'll probably keep the drive for spares for now since it is not my only one.
-Timo

[gerald]

Comming late to the party 

I'll second Bryce and adding that it can also be a head preamp failure.
On this version of the drive a swap of the main PCB is relatively easy with exception of the track0 sensor which is better de-soldered rather than unmounted (it's a pain to re-align properly).
That would tell you if the head are OK or not.

[Audronic]

@timovo


Just a thought, with a blank (magnetically erased disk "using a magnet") just try to format the disk and see what happens ?
and if that passes try a "CAT"


Good luck


Keep Safe


Ray

[Bryce]

@timovo


Just a thought, with a blank (magnetically erased disk "using a magnet") just try to format the disk and see what happens ?
and if that passes try a "CAT"


Good luck


Keep Safe


Ray

Using a magnet isn't necessary. Just standard reformatting and testing will tell you whether it's just a calibration issue.

Bryce.

[Audronic]

@Bryce


The reason for the Use of the magnet is assure that you are not being fooled by existing format information on the disk.
and what you are reading back is your New format info and not Old info.
This is the method That have used for some decades.


Thanks for the thought


Keep Safe


Happy new Year


Ray

[timovo]

Thanks for suggestions!
I tried the magnet & formatting -method. Updated the original message with the result.
-Timo