Amstrad CPC 6128 - Not all disks are loading

[gerald]

Sorry to jump in but I'm having the same issue with a DDI-1 / FD-1:

I replaced the drive belt, cleaned capstans and head in my DDI-1. CPC464 edge connectors and DDI-1 connections cleaned with isopropanol.

However approx. 50%of my game disks including my beloved UN Squadron give 'read error'. The UN Squadron disk is part of a 3 disk US Gold collection, all of which give 'read error'. All my populated Maxell and Dixons 3" disks cat and load fine.

If all the disks your drive has written can load but not the commercial one it is likely an alignment problem. This cannot be fixed easily. You need at least an oscilloscope to do it.

Interestingly my SWIV game disk began to load, hung and now reports 169k free  . It is also strange that it is just my commercial game disks that are affected.

SWIV has not file in the directory structure, so that's expected. You start it by |CPM

Is this the same issue as Neil79? I was planning on getting a HxC and modding DDI-1 and cable as per Bryce's guide, so is the procedure with the disk tool and adjustment the same for a DDI-1 / FD-1?

The speed adjustment is valid for DDI/FDI and internal drive. A first step is to just check the speed. Now the issue will be to transfer the tool (I am personnally using RPM) to disk.

[gerald]

Do tell? Also how do you take that bloody lid off 

The one on the wiki had a soldering point that connected the lid to the PCB. You 1st need to remove that soldering point.
Next is to get the lid out of the motor shell, and since it is forced in, that's not an easy task.

[Neil79]

The one on the wiki had a soldering point that connected the lid to the PCB. You 1st need to remove that soldering point.
Next is to get the lid out of the motor shell, and since it is forced in, that's not an easy task.

Na mine's just like this http://www.cpcwiki.eu/index.php/File:EME-156_RpmAdjust.jpg


But how to get it out when there only place to get a screwdriver in, is near the electrical points 

[gerald]

Na mine's just like this http://www.cpcwiki.eu/index.php/File:EME-156_RpmAdjust.jpg


But how to get it out when there only place to get a screwdriver in, is near the electrical points 

The lid is connected at ground just where the brown wire is soldered to PCB.
Once this soldering is removed (with desoldering wick) the only access is indeed at the wire connection.
You need to protect it and make sure you do not break the PCB. Did I say it's not an easy task 

[Neil79]

Nope I can't do anything with it, so yeh I think I killed it. So much for just push the screwdriver in slightly and turn 


Oh the lids off!!    Found out why it wasn't working

[Neil79]

 

[pelrun]

Ouch. Yeah, you did just what I did. Hopefully you're lucky and the winding on the rotor is ok; if it's shorted/damaged you probably can't fix it.

To repair it you'll need to solder on a replacement pot (I *think* it was 10k linear, the original pot should have "103" on it if it is, or 104 if it's 100k) and then reassemble it.

Reassembly requires that you remove the rotor from the casing (remove the casing from the drive; it's just held on by two screws.) so you can get the brushes back onto the commutator properly. And that means getting the capstan off the shaft. If you have/can get a pinion puller tool this will be easy, otherwise it'll be hard. I filed down a nail so that it was a little narrower than the shaft, put the motor vertical on a couple of blocks such that it was only held up by the casing and the rotor could fall out, then knocked the shaft out of the capstan using the nail and a hammer. Make sure you don't lose the thin plastic washers.

Edit: at this point carefully inspect the rotor and the casing(stator), and remove any metal shavings or debris that might be present.

Reassemble the rotor and the PCB, fitting the commutating ring between the brushes carefully, and so the shaft end fits into the plastic bearing in the centre of the pcb. Put the rotor back into the casing (will be hard because the magnets will pull it sideways) and the shaft through the end bearing, then set it upright on the bench and tap the capstan back onto the shaft with the hammer. This will probably mess up the plastic bearing on the other end a bit, but it wasn't an issue for me. Then use a couple of spots of hotglue to fix the pcb into the casing since you probably won't get the lid back on (I couldn't.)

[simondo]

gerald
Thanks. Had a look a the DDI-1 service manual at the alignment procedures. Although I have access to an oscilloscope I don't have a CF2 test disk. Also the procedure is quite technical, and where I work I only use an oscilloscope to do a simple check & adjust of waveforms generated from amplifiers.
When I get a HxC I will check rpm using disk check program, but beyond that, and as Neil79 says, it's not worth it in case I damage it.

Neil79
I feel your pain, and after your experience I may not bother tinkering any further. I hope you get it sorted, you've got the best support possible here.

[gerald]

The original pot seem OK, just pushed away from it soldering point (bad reflow ?). But re-assembly seems really tricky 

It looks like a MMA-6U2LEP drive. This one has a white rubber on the adjustment hole.
The one on the wiki is a MMU-5B2LQJ ans has a black rubber on the adjustment hole.

[Bryce]

I've repaired one of these in the past and I don't remember having to remove the rotor to get the PCB back in. There is a trick to getting the brushes back onto the commutator from above while it's in the case, but it takes a lot of poking around with a needle.

Bryce.

[Neil79]

Nope it's *****, the two strips of metal which seem to attach across to the center are damaged, I seriously can't be done with this now.


If I can't do a motor fix, i might as well ditch it and look towards putting the HxC inside the system

[Bryce]

Send it over and I'll sort it out.

Bryce.

[Neil79]

Send it over and I'll sort it out.

Bryce.

I've got one more chance at this, dad's a train engineer ( good with soldering etc )


I've got to ask this though, the two tiny flap metal brushes , look like fingers going towards the center. Do they need to be close to the center hole when placing it down, or far enough away then maneuvered back?

[Bryce]

They're the brushes that supply the rotor with current. They should push relatively well against the commutator (metal ring around the shaft made of four seperate contacts) for the motor to work properly.

Bryce.

[pelrun]

And the brushes have to be the right way around. If you get it wrong (like I did) then the disc will spin backwards, and in my case it made a nasty squeaking noise while it did so. Make sure the disc spins clockwise!