EME-155 stepper motor only moving the reader head outwards.

Started by oli71fr, 11:15, 20 July 22

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oli71fr

Hello everybody, 

I have been lugging my CPC6128 around Europe and we are now in Estonia, where it was stored for a while.

All works except the drive, and it is the stepper motor that is troublesome. 
The belt was replaced in 2012 and it is still OK.

I have taken it apart, having previously marked its position but it stubbornly wants to turn only one way bringing the head outwards from the disc centre.

I am wondering what can cause this.

I am thinking that it is possible all the connections on the motherboard where the FDD cable attaches are not all continuous, or 

the other possibility is if the wires are not connected correctly or disconnected on the edge of the motor itself. 

Maybe I should post a video. It will speak a 1000 * 1000 words.

None of the wires are sticking out and all the solder points look clean with no cracks, I have "wetted" all connections and checked them with the multimeter for continuity. 

The drive detects files on the discs with CAT, but this can only be done once by sliding the head down manually and letting the step motor bring it up to the top, and it does not necessarily repeat because as the head goes up it puts itself out of sync.

It is as if the information for the head to go down towards the centre of the disc is inverted and pushes the head outwards.

I am dismissing belt or RPM issues because the drive still reads using CAT, maybe I am wrong in that assumption.

The Drive is an EME-155.

Thanks in advance for any comments. It is fantastic to have such a community.

Bryce

Check for dry solder joints on the connector sockets to the motor.

Bryce.

oli71fr

Hello Bryce, and thank you very much for the super quick response.

I got hold of a soldering iron and I wetted the solder of these 4 connections and they are continuous.
I will go through this checking again to make 100% sure and verify continuity to the motor if I can reach it.

Do you mean the connections on the motor itself (all 4 are in a square attached coming out the stator with transparent ends)? - I am a bit loathed to pulling these out as I have no way of seeing how the wires are attached to the motor.

Best regards

Olivier

Bryce

No, I meant the connectors on the drives PCB. They are small white headers and are known to fail. Also check the solder joints on the power and flat cable connections on the drives PCB.

Bryce.

oli71fr

Hello Bryce

I checked for continuity at all the locations shown in the Flickr links below :

Stepper Motor cable socket on the drive board
https://www.flickr.com/photos/monsieurbond/52275896427/in/album-72157638710759703/

Main cable and Power cable attachment pins
https://www.flickr.com/photos/monsieurbond/52276869911/in/album-72157638710759703/

Stepper Motor Cable ends
https://www.flickr.com/photos/monsieurbond/52276869981/in/album-72157638710759703/

I also took the soldering iron to wet the locations.  The other side of the board looks like this
https://www.flickr.com/photos/monsieurbond/52276039772/in/album-72157638710759703/

The continuity is there. I also took the mainboard out to check for any issues, but I could not see any with the magnifying glass

As soon as the videos have uploaded, I will add the links to this post.
Video1
https://www.flickr.com/photos/monsieurbond/52276081467/in/album-72157638710759703/

Sadly I still have the erratic movement of the Head issue.

Thanks for the help so far.

Best regards

Olivier


Bryce

Did you re-solder the connections on CN3/4/5/6 on the bottom of the board? It doesn't look like you did in the picture.

Bryce.

oli71fr

Hello Bryce, thank you.

I am quite certain I did, but I will re-do those as soon as I can, just to eliminate them. 

I definitely did CN6.
Should I add more solder? At the moment I just touched the solder to liquefy it and leave as soon as it emits a puff of smoke.

Best regards

Olivier

Bryce

You have to add more solder, not just melt them. New solder contains flux, the old stuff doesn't.

Bryce.

oli71fr


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