Filled Repair of Amstrad CTM-644 (CPC colour monitor)

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Jonathan

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I originally asked this on the CPCWiki forum and it was suggested that I ask here. I live in Yorkshire and apparently there are people on this forum near me who may be able to repair the monitor.

The three colours are misaligned. Bryce (who also posts here) said that the solution was to adjust the colour gun levers, but I am reluctant to do this myself...

I don't know whether it's a separate problem, but the screen display isn't rectangular - it's wide at the top and narrows symmetrically as it goes to the bottom of the monitor.

Thank you in anticipation!
 

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I second the Roy recommendation, when my monitors die it's Roy time :)
 
ill give it a go,but baer in mind the monitor has a pretty bad problem id guess a short in the deflection yolk
give me a sec ill respond to the pm you sent :)


please dont adjust anything in the monitor,itll have zero effect on this problem,thanks
 
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monitor is here,i havnt opened the package yet

ill update the thread,probably later
first ill let the op know its here via pm,this reply is to let the mods know its in progress,thanks :)
 
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this is now repaired,pictures incoming
ill look at the reciecer you sent later on
im a bit tired,ill let also let you know via pm

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Top job Roy! It was me who originally sent Jonathan over here. Now he knows why :)

Bryce.
 
I thought so too, but it wouldn't have been worth sending it over to Germany and back, which is why I pointed him in your direction.

Bryce.
 
yep,it would of been a nightmare
its already bad enough shipping it around the same country
shame really as its fairly common for these to die this way
 
great work - as expected - Roy!

I wonder, is there anything to do to preserve these? some new coating on yoke? some bag of silica gel inside the monitor?
I also have one packed and I would hate to see it go bad ...
 
The problem with the deflection coil is that the copper has a very thin coat of lacquer insulation. Over time it gets brittle and cracks due to age and heat. The copper is permanently expanding/contracting and cracks the lacquer coating when it has got too dry/hard. There's nothing you can do to stop this as it happens inside the coil, not just on the surface.

Bryce.
 
yep,true,i have also found its also due to storage,like damp and humid places with large fluctuations in temps
they corrode and go brittle as bryce has said,which can mke them short to near by coils or back of tube which is grounded
obvuosly ive had to repair this,which means removing the corrosion and cleaning the area and applying a layer of lacour then tape ,repair any broken wires then more laqour and tape for insulation
as you can imagine its not the faint of heart,so chances of an actual repair without replacing the yolk is slim,i got lucky with this one,and yes its very time consuming
and yes it also involves removing the entire tube assembly which is a task on its own,and requires a setup after
definently not for amatuer repair enthuiasts,so i cant really suggest anyone attempt it and have a reseasonable succes rate,as its far from easy
 
definently not for amatuer repair enthuiasts,so i cant really suggest anyone attempt it and have a reseasonable succes rate,as its far from easy

That’s pretty much what my wife and daughter said too :)

I really appreciate the hard work you have put into this to keep the monitor going for another generation!
 
i was happy to do the work and still am :)

i hope it carrys on working for some time to come,ill give you some tips in pm while in use,when this is over
 
small update

im waiting on parts to repair the mp3 tuner that was sent with this,ill update the thread when i get somewhere
 
the tuner is now repaired,i think
it would turn on had power etc ,but wouldnt tune into anything
basically,i worked backwards through the rf,untill i got to the AGC which seemed to have runaway regulation
isolated it from the rf,nothing,no change
tried to adjust it out,no change
i replaced the LA7520N and did a setup,that seems to have fixed it(abridged,so there isnt a wall of text)
pictures below
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The monitor and MP-3 tuner arrived back here safely a few days ago, and are working well!

Thank you very much again.

So far we have mostly been using the tuner with an old Atari 2600, to play Pacman, Outlaw, Moon Patrol and other old favourites :)
 
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