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.

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.

Re: Faulty Microvitec Monitor help please!
 

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

Keith

Re: Faulty Microvitec Monitor help please!
 

It does look like faulty scan coils, but yes check for dry joints first.

Re: Faulty Microvitec Monitor help please!
 

Almost certainly faulty scan coils unfortunately, seen it many times before.

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!

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.

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.

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.