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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

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Old 30th Nov 2020, 9:42 pm   #41
1955APREN
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Default Re: Faulty CRT Computer Monitor

Sorry for the delay I have in my shed a A34JXV70x53 with scan coils you are welcome to have FOC it but it will be collect only from north Shropshire . I don't think the Greek god
will look after it on a 200 mile + run
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Derrick
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Old 15th Dec 2020, 12:01 am   #42
tjohnson
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Default Re: Faulty CRT Computer Monitor

Quote:
Originally Posted by 1955APREN View Post
Sorry for the delay I have in my shed a A34JXV70x53 with scan coils you are welcome to have FOC it but it will be collect only from north Shropshire . I don't think the Greek god
will look after it on a 200 mile + run
Regards
Derrick
Thanks thats very generous I might take you up on this if my current plan doesn't work and once all this covid stuff lifts.

I have taken the tube and yoke out the philips however the connector isn't a straight swap. The original yoke follows what appears to be a fairly standard configuration and colour combination

red & blue horizontal winding - green & yellow vertical winding

while the philips follows

red & black horizontal winding - green & grey vertical winding

I'm now concerned about getting them the wrong way round and impact this may have.

I believe on the original tube the blue and green are negative but on the philips it seems like the grey and black are negative.

They sure did make this ackward!
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Old 15th Dec 2020, 7:27 pm   #43
tjohnson
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Default Re: Faulty CRT Computer Monitor

I went ahead and tried it today, some success but the picture is mirrored, it is showing backwards!!!

It's also quite a bit darker than the old picture even with the brightness turned all the way up.
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Old 15th Dec 2020, 7:31 pm   #44
Red to black
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Default Re: Faulty CRT Computer Monitor

Swap the Horizontal scan coil connections over (with each other, ie. just that pair) and this will correct the image.
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Old 16th Dec 2020, 12:28 am   #45
tjohnson
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Default Re: Faulty CRT Computer Monitor

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Originally Posted by Red to black View Post
Swap the Horizontal scan coil connections over (with each other, ie. just that pair) and this will correct the image.
Cheers that did the trick. I also adjusted the sub-bright inside the monitor and got an acceptable brightness, the service manual refers to putting the monitor into "free-run condition" and then connecting a scope of the collector of Q802 and then obtaining 123-124v but I had no idea on what it meant by free-run condition, I thought it perhaps means connecting nothing , but using my scope I wasn't getting what the manual showed so I did it by eye. ICP-N20 was blown but the HOT wasn't, I didn't notice that there is an internal diode that made me think they were shorted together.

I need to tweak the horizontal and vertical positions slightly but it looks good, the picture is probably crisper than the old tube, unfortunately there are some surface scratches on the tube but since it was free I can't complain too much and I have a working monitor again!
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Old 20th Dec 2020, 12:54 am   #46
Kyle__B
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Default Re: Faulty CRT Computer Monitor

Good work. I'm not surprised that the replacement tube is sharper, knowing amstrad the original was probably factory seconds.
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