Author Topic: Disc drive EME 156 stepper motor screws  (Read 397 times)

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Offline JupiterJones

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Disc drive EME 156 stepper motor screws
« on: 12:05, 20 August 21 »
Hello all,


Hope everyone is well! I need a bit of your help with my CPC 6128 EME 156 disc drive.


I've managed to fix the whole system and now it works reliably. However some discs can be read reliably while some others can't. If I also format a disc, it has no issues using it whatsoever, so I guess now it must be time to adjust stepper motor as explained in Noel's Retro Lab fantastic video :

https://youtu.be/WK0QoVNVO2w


But my problem is removing the screws. I have some good quality screwdrivers but still not able to remove them safely. The most accessible one I eventually removed it usign miniature pliers but second one is not enough accessible to use them. It seems it has been fixed with some kind of screw/bolt fixer, which makes them to be tightly attached. Applying force to it seems to ruin screw's slot for screwdriver.


I've read somewhere that using some heat on screws and screw-fixer might eventually loosen it... So here my two questions:


1) Has anyone tried to apply heat over screw / screw-fixer to loosen it? Some advice, like use the soldering iron or hot air blower?
2) Does anyone know which screws can be used to replace the old ones? I think they must be something like M2 or so, but I don't even know if these screws are metric or imperial...


Any help will be greatly appreciated!
« Last Edit: 12:42, 20 August 21 by JupiterJones »
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Offline Bryce

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Re: Disc drive EME 156 stepper motor screws
« Reply #1 on: 12:55, 20 August 21 »
Hi,
      the screws are usually fixed with locktite (red glue). You can usually "crack" them ie: loosen them with a sudden sharp turn. If not you can try scratching the red glue off or tapping the head of the screw. If that doesn't work you can heat the head of the screw with your soldering iron, but don't try to remove the screw until it has cooled down again.

Bryce.
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Offline Gryzor

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Re: Disc drive EME 156 stepper motor screws
« Reply #2 on: 13:10, 20 August 21 »
Was looking at an impact screwdriver set with some nice small bits just yesterday... :D
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Offline JupiterJones

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Re: Disc drive EME 156 stepper motor screws
« Reply #3 on: 13:23, 20 August 21 »
Hi,
      the screws are usually fixed with locktite (red glue). You can usually "crack" them ie: loosen them with a sudden sharp turn. If not you can try scratching the red glue off or tapping the head of the screw. If that doesn't work you can heat the head of the screw with your soldering iron, but don't try to remove the screw until it has cooled down again.

Bryce.


Hello Bryce! Thanks for the advice. I tried the sudden sharp turn trick but maybe I'm not strong enough, so the screwdriver slipped off screw's head... I'll give a try your next two advices!


On the other hand, wouldn't you know which kind of screws are? Regrettably I don't have a caliper at hand so I'm unsure wether these are M2, M2.5... Or maybe even imperial. I damaged one of the screws when removing it using pliers...  :picard:
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Offline Bryce

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Re: Disc drive EME 156 stepper motor screws
« Reply #4 on: 14:09, 20 August 21 »
I don't have a drive here at the moment, but they definitely aren't imperial. Probably M2.5

Bryce.

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Offline JupiterJones

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Re: Disc drive EME 156 stepper motor screws
« Reply #5 on: 18:03, 20 August 21 »
Hi Bryce,


I've managed to remove that last rogue screw, just by using my old multiuse swiss knife. For some reason, knife's philips screwdriver bit grips far better than other tools I have. After tapping screw's head a couple of times and applying some firm pressure against the head, it eventually moved.


Regarding replacement, I initially thought it ust be metric, but as Amstrad was a British company it could be possible they decided to use imperial instead of metric. I'll take some M2.x screws and give them a try.


Thank you very much!
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Offline Bryce

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Re: Disc drive EME 156 stepper motor screws
« Reply #6 on: 21:48, 20 August 21 »
The only computer company I know of that used imperial screws was BBC, all the others, including Spectrum, Oric and even Jupiter used metric screws.

As for the driver fitting properly. Most people think that "Philips screws" (cruciform) are all the same. When in fact there are so many different versions with different profiles, depths and angles. Take a look here: https://en.wikipedia.org/wiki/List_of_screw_drives

I tend to use JIS or Pozidriv screwdrivers because they seem to work best on most screws. And never buy cheap screwdrivers! The metal is usually too soft, they will give way and sheer the profile off the head, making the screw almost impossible to remove.

Bryce.
« Last Edit: 21:49, 20 August 21 by Bryce »
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Offline Audronic

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Re: Disc drive EME 156 stepper motor screws
« Reply #7 on: 01:25, 21 August 21 »
I have used this method :-


Using a hacksaw blade (Fine teeth) cut a line across the head and away you go.
I have had to use this method on about 4 drives, Don't cut to deep as the head will fall off.


Good Luck


Keep Safe


Ray
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Offline JupiterJones

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Re: Disc drive EME 156 stepper motor screws
« Reply #8 on: 12:26, 23 August 21 »
The only computer company I know of that used imperial screws was BBC, all the others, including Spectrum, Oric and even Jupiter used metric screws.

As for the driver fitting properly. Most people think that "Philips screws" (cruciform) are all the same. When in fact there are so many different versions with different profiles, depths and angles. Take a look here: https://en.wikipedia.org/wiki/List_of_screw_drives

I tend to use JIS or Pozidriv screwdrivers because they seem to work best on most screws. And never buy cheap screwdrivers! The metal is usually too soft, they will give way and sheer the profile off the head, making the screw almost impossible to remove.

Bryce.


Again, thank you very much! I'll read that wiki page... And thanks for the advice on screwdrivers. Mine were supposed to be good enough, not very cheap but for sure not industrial grade. Metal says it is chome-vanadium alloy, and it seemed to me these must do the job... I'll replace them for sure.
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Offline Bryce

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Re: Disc drive EME 156 stepper motor screws
« Reply #9 on: 14:40, 23 August 21 »
If they are made of Chrome-vanadium they are probably pretty decent screwdrivers, but the material isn't the main factor here, rather the shape of the cross.

Bryce.
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Offline JupiterJones

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Re: Disc drive EME 156 stepper motor screws
« Reply #10 on: 11:52, 24 August 21 »
Finally I managed to get me a caliper and did some measurement on these screws. Bryce, you were right, screws are M2.5x5


Thanks!
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