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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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8th Feb 2020, 10:35 am | #1 |
Diode
Join Date: Feb 2020
Location: Oakham, Rutland, UK.
Posts: 2
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Faulty Microvitec Monitor help please!
I am trying to repair a 1431MS4C "BBC" monitor with an E-W fault (see picture).
The HT voltage is correct and the EHT is OK at 24kV. I would be grateful for some ideas as to the cause of the fault. |
8th Feb 2020, 10:52 am | #2 |
Nonode
Join Date: Jun 2007
Location: Coulsdon, London, UK.
Posts: 2,163
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Re: Faulty Microvitec Monitor help please!
I would start by looking at the soldering with a magnifying eyepiece to see if there were any 'dry joints'.
Start with the large resistors and transformer connections. |
8th Feb 2020, 11:50 am | #3 |
Nonode
Join Date: Aug 2007
Location: South Bradford, West Yorkshire, UK.
Posts: 2,573
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Re: Faulty Microvitec Monitor help please!
Could be corrosion on the scan coil windings causing shorted turns.
Keith |
8th Feb 2020, 12:11 pm | #4 |
Dekatron
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,431
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Re: Faulty Microvitec Monitor help please!
It does look like faulty scan coils, but yes check for dry joints first.
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Frank |
8th Feb 2020, 2:13 pm | #5 |
Nonode
Join Date: Mar 2010
Location: Sunderland, Tyne and Wear, UK.
Posts: 2,474
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Re: Faulty Microvitec Monitor help please!
Almost certainly faulty scan coils unfortunately, seen it many times before.
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I don't suffer from Insanity. I enjoy every minute of it. |
8th Feb 2020, 4:09 pm | #6 |
Diode
Join Date: Feb 2020
Location: Oakham, Rutland, UK.
Posts: 2
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Re: Faulty Microvitec Monitor help please!
I was wondering about the scan coils.I've been through the joints and tested/replaced components.
Thanks for the replies! |
10th Feb 2020, 4:40 pm | #7 |
Dekatron
Join Date: Apr 2005
Location: North Wales, UK.
Posts: 6,916
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Re: Faulty Microvitec Monitor help please!
What make of CRT is it? I imagine it'll be one of the red label type fitted to Orions with the corroding scan coils. Unfortunately, as it's a monitor, scan coil repair will be unlikely to give a good enough display. I'm sure all my CRT coils are long since gone, but I will have a look just in case.
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12th Feb 2020, 2:54 pm | #8 |
Dekatron
Join Date: Dec 2007
Location: Haarlem, Netherlands
Posts: 4,199
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Re: Faulty Microvitec Monitor help please!
A replacement scan coil should work, though only after careful adjustment.
Repairing the scan coil should be attempted first anyway. There's a chance of geometric distortion due to the winding position being different after repair but you may be able to keep it to a minimum. |
12th Feb 2020, 3:27 pm | #9 |
Dekatron
Join Date: Aug 2006
Location: Madrid, Spain / Wirral, UK
Posts: 7,498
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Re: Faulty Microvitec Monitor help please!
Measure the resistance of the coils and check/replace any capacitors at the deflection outputs. I once got lucky with a PC monitor with similar symptoms to yours.
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Regards, Ben. |