Bush TV22A increasing brightness - UK Vintage Radio Repair and Restoration Discussion Forum

chriswood1900 · 2nd Sep 2023, 12:06 pm

I need a quick bit of advice on repairing my Bush TV22A which I have recently brought out of storage and used a few times. It has recently started to increase in brightness and lose contrast after it has been on for an hour and the flyback lines appear. I’m assuming it is probably a fault around the video output valve with a component drifting but I was hoping that someone who knows these sets better could point to where to look for the fault.
Thanks

FERNSEH · 2nd Sep 2023, 12:33 pm

Anode load resistor of the video amplifier gone high value?
Check the CRT first anode voltage for variation over a given time.

DFWB.

FERNSEH · 2nd Sep 2023, 2:52 pm

CRT circuits in the Bush TV22A and TV22C.

DFWB.

chriswood1900 · 2nd Sep 2023, 5:50 pm

Thanks FERNSEH.
I will try to do it next week and report back.

chriswood1900 · 11th Sep 2023, 7:55 pm

Thanks again that was a straight forward repair the anode resistor had risen in value from 10K to 12.6K and as it warmed up went up from there so I replaced it with a modernish 1W resistor of similar size.

2 Hour soak test and a nice clear stable picture again.

2nd Sep 2023, 12:06 pm	#1
chriswood1900 Octode Join Date: Jan 2007 Location: Dorridge, West Midlands, UK. Posts: 1,575	Bush TV22A increasing brightness I need a quick bit of advice on repairing my Bush TV22A which I have recently brought out of storage and used a few times. It has recently started to increase in brightness and lose contrast after it has been on for an hour and the flyback lines appear. I’m assuming it is probably a fault around the video output valve with a component drifting but I was hoping that someone who knows these sets better could point to where to look for the fault. Thanks __________________ Chris Wood BVWS Member

2nd Sep 2023, 12:33 pm	#2
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,459	Re: Bush TV22A increasing brightness Anode load resistor of the video amplifier gone high value? Check the CRT first anode voltage for variation over a given time. DFWB.

2nd Sep 2023, 2:52 pm	#3
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,459	Re: Bush TV22A increasing brightness CRT circuits in the Bush TV22A and TV22C. DFWB. Attached Thumbnails

2nd Sep 2023, 5:50 pm	#4
chriswood1900 Octode Join Date: Jan 2007 Location: Dorridge, West Midlands, UK. Posts: 1,575	Re: Bush TV22A increasing brightness Thanks FERNSEH. I will try to do it next week and report back. __________________ Chris Wood BVWS Member

11th Sep 2023, 7:55 pm	#5
chriswood1900 Octode Join Date: Jan 2007 Location: Dorridge, West Midlands, UK. Posts: 1,575	Re: Bush TV22A increasing brightness Thanks again that was a straight forward repair the anode resistor had risen in value from 10K to 12.6K and as it warmed up went up from there so I replaced it with a modernish 1W resistor of similar size. 2 Hour soak test and a nice clear stable picture again. Attached Thumbnails __________________ Chris Wood BVWS Member