CPC6128 Disk drive stepper

freenutella · 21:11, 16 July 20

Hi

I just bougth a CPC6128 with disk drive problem (a ME57PBIO model). I would like to play to my favorite kid game: gryzor!!
the first problem was simple (after reading this wiki) -> the 12v was cut. A small repair and now the motor spin.

But (there is always a but) the steeper motor does not seems to work.

I can manipulate the axis freely.
Could you advice me how to test wether it come from an electric problem or a motor problem?

I tested on the board the CN3 connection and I can find a 1,5V on PIN3 but I cannot say if its normal or not (the schematic is hard to read for me).

A last question, if I don't succeed to repair it; should I replace it with a Sinclair ZX Spectrum +3 Disk Drive? The amstrad 6128 seems difficult to find.

Thanks for your help;

Bryce · 08:11, 17 July 20

The most likely cause for this is dry joints on the connector header.

Bryce.

freenutella · 09:04, 18 July 20

Thanks Bryce!

When you say dry joints -> it means that I should resolder the wire on this side

Or on this side?

Best regards

tjohnson · 11:02, 18 July 20

On the bottom picture on the green pcb some of the jobs on the headers might be dry and cracked if you look closely, little circular cracks around the pin. If you can solder do them all, I had the same problem on one of my drives and reflowing those joints solved the issue.

Bryce · 14:05, 18 July 20

Quote from: tjohnson on 11:02, 18 July 20
On the bottom picture on the green pcb some of the jobs on the headers might be dry and cracked if you look closely, little circular cracks around the pin. If you can solder do them all, I had the same problem on one of my drives and reflowing those joints solved the issue.

What he says.

Bryce.

freenutella · 10:16, 19 July 20

Hi

Thanks for your advice.
I re solder the CN3 4 joints. I have now a 0,2v connection on PIN 3 and 4 and 0V for 1 and 2.
I tried to test the voltage which directly arrive to the motor -> there are 2 copper wire which enter directly in the motor (just after the little pcb board atteched to the motor).

I cannot find voltage on this place

On more info, the message on the screen is that the disc is missing (the disk is in the floppy)
May be the stepper isn't activated because the flopppy doesn't detect the disK?

Best regards

tjohnson · 10:53, 19 July 20

Have you reflowed all solder joints on all the connector points not just the stepper motor , do the ones that connect the 21 pin cable to the cpc.

freenutella · 20:20, 19 July 20

hello

I reflow all the joints that are connected to the 21 pin and .. nothing more

The stepper doesn't work.
Do you know which voltage I should find on the pin connected to the stepper?

For the moment I find around 0,2V on the 2 first pin.

And do you have some additional test I sould do to determine if it's motor or an electric problem?

Best regards,

Bryce · 08:38, 20 July 20

The motor should be getting 12V, so something is wrong on the PCB. You'll need to trace the 12V from the source to see where it stops. The motor is most likely fine.

Bryce.

freenutella · 12:54, 25 July 20

Thanks Bryce.
I will take my voltmeter to see where the trace is broken.

Bets regards,

Bryce · 13:25, 25 July 20

I may not be a broken trace, there are several components between the 12V source and the motor.

Bryce.

freenutella · 20:59, 25 July 20

Hi

Maybe I"am wrong but with a floppy disk where the stepper works the voltage on the CN2 pin is not 12v

There are 4 pins and 2 are 0v and 2 with 0,9V.

On the shematic (I am a newbie in schematic reading) the voltage doesn't seems to be 12v

Best regards

GeoffB17 · 21:45, 25 July 20

Hello,

The bits of the circuit you're looking at it not the right place. A bit to the left you'll see an IC2, a HA13421, this is the Stepper Motor controller, and next to this on the circuit is CN3, I'm sure THIS is the stepper motor. Yes, the voltages shown are 5V, not 12V.

CN2 is a photo-sensor. CN3 was mentioned at the top of this thread!

Geoff

freenutella · 21:05, 26 July 20

Hello

Thanks. Its clearer for me

I just found it and the schematic.
I will check voltage because I don't have 5v. I will trace where the 5V comes from.

I just suspect that the 5V is 'on' only when the motor should be on. Do you know if it's the case? or if the 5V should be always on?

Best regards

Bryce · 22:00, 26 July 20

Define "on". Voltage is never "on", it's just present at an established point. Where do you think 5V should be on (or not on)?
Bryce.

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CPC6128 Disk drive stepper