UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Television and Video

Notices

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

Reply
 
Thread Tools
Old 8th Feb 2020, 10:35 am   #1
meter pan
Diode
 
Join Date: Feb 2020
Location: Oakham, Rutland, UK.
Posts: 2
Default 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.
Attached Thumbnails
Click image for larger version

Name:	DSCN5035.jpg
Views:	210
Size:	122.3 KB
ID:	198597   Click image for larger version

Name:	DSCN5043.jpg
Views:	229
Size:	74.0 KB
ID:	198598  
meter pan is offline   Reply With Quote
Old 8th Feb 2020, 10:52 am   #2
Silicon
Octode
 
Join Date: Jun 2007
Location: Coulsdon, London, UK.
Posts: 1,099
Default 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.
Silicon is offline   Reply With Quote
Old 8th Feb 2020, 11:50 am   #3
KeithsTV
Nonode
 
KeithsTV's Avatar
 
Join Date: Aug 2007
Location: South Bradford, West Yorkshire, UK.
Posts: 2,267
Default Re: Faulty Microvitec Monitor help please!

Could be corrosion on the scan coil windings causing shorted turns.

Keith
KeithsTV is offline   Reply With Quote
Old 8th Feb 2020, 12:11 pm   #4
Nuvistor
Dekatron
 
Nuvistor's Avatar
 
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 7,489
Default Re: Faulty Microvitec Monitor help please!

It does look like faulty scan coils, but yes check for dry joints first.
__________________
Frank
Nuvistor is offline   Reply With Quote
Old 8th Feb 2020, 2:13 pm   #5
Red to black
Octode
 
Red to black's Avatar
 
Join Date: Mar 2010
Location: Sunderland, Tyne and Wear, UK.
Posts: 1,886
Default Re: Faulty Microvitec Monitor help please!

Almost certainly faulty scan coils unfortunately, seen it many times before.
__________________
I don't suffer from Insanity. I enjoy every minute of it.
Red to black is offline   Reply With Quote
Old 8th Feb 2020, 4:09 pm   #6
meter pan
Diode
 
Join Date: Feb 2020
Location: Oakham, Rutland, UK.
Posts: 2
Default 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!
meter pan is offline   Reply With Quote
Old 10th Feb 2020, 4:40 pm   #7
Welsh Anorak
Dekatron
 
Welsh Anorak's Avatar
 
Join Date: Apr 2005
Location: North Wales, UK.
Posts: 4,471
Default 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.
__________________
Glyn
www.gdelectronics.wales
Welsh Anorak is offline   Reply With Quote
Old 12th Feb 2020, 2:54 pm   #8
Maarten
Nonode
 
Join Date: Dec 2007
Location: Haarlem, Netherlands
Posts: 2,744
Default 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.
Maarten is offline   Reply With Quote
Old 12th Feb 2020, 3:27 pm   #9
ben
Dekatron
 
ben's Avatar
 
Join Date: Aug 2006
Location: Madrid, Spain / Wirral, UK
Posts: 5,651
Default 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.
__________________
Regards,
Ben.
ben is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 7:04 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Copyright ©2002 - 2020, Paul Stenning.