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

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Old 22nd Sep 2018, 3:20 pm   #61
high_vacuum_house
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Smile Re: Stuck on a BRC 1400!

Your set is coming along nicely. the tube is coming up well

Here is my HMV working on the 625 line system now the UHF modulator has arrived. It is very difficult to get a decent picture with the camera due to the strobing effect. The picture and sound quality is excellent. The BVWS Gerald Wells DVD is being shown here.

I decided to try out my Thorn 1590 television at the same time to compare them.

I had a close shave with this one though. I had them running side by side but the 1590's contrast was horrible and the width and height were excessive. On going over the top to tweak the height and width controls I could see the set lit up inside rather well through the ventilation holes. The CRT heater was more of a lightbulb than a heater!!

On removing the back and pulling the CRT base off the 11 volt HT1 line was more like 15-18 volts! Going round the regulator showed the set HT volts pot (220 ohms) was O/C. replacement and adjusting cured the fault and it looks like the CRT got away with it. I ran the set for an hour with a DMM across the HT1 line and it was pretty stable. I wonder how long it would have lasted if I hadn't spotted the excessive picture size?

I could not get a good picture with them side to side due to strobing. Either one or the other would have a dark band across the screen.

Christopher Capener
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Old 22nd Sep 2018, 4:25 pm   #62
Focus Diode
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Default Re: Stuck on a BRC 1400!

The HMV looks fantastic Christopher. Well done. I've ordered another modulator myself to further check 625. So far I've only tried it through a VCR playing a VHS tape.

As for the nasty 1591 fault I understand a power resistor can go o/c causing similar symptoms. The only obvious symptom to the viewer is some overscan. If lucky a major transistor might fail before the CRT is ruined.

Well done on finding the cause of your problem.

Cheers
Brian
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Old 23rd Sep 2018, 12:18 pm   #63
Welsh Anorak
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Default Re: Stuck on a BRC 1400!

Well spotted on the 1591. The PNP regulator could leak with the voltage creeping as the set warmed up. The set HT controls did do this back in the day, but often intermittently. The 14" tube wouldn't tolerate this for more than a few minutes; your 12" one won't show any ill effects.
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Old 23rd Sep 2018, 10:16 pm   #64
Focus Diode
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Default Re: Stuck on a BRC 1400!

Just a thought on the 1400 chassis. The local distance control works on 405-line VHF only.

However, if Tag 43 is moved to tag 44 allowing 625-line VHF reception, not only do the 405 and 625 contrast controls work but the Local Distance control becomes functional on 625 UHF!

Worth doing this if overloading is apparent which is a possibility with modulators.

405-line VHF works just as well. 625 VHF reception only works if the supply to the system switch solenoid is disconnected

Brian.
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Old Yesterday, 5:21 pm   #65
Focus Diode
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Default Re: Stuck on a BRC 1400!

Thank you so much for the knobs Keith.

Found one of my spare VHF tuners which thankfully came complete with microswitch.

I'll try a transplant later.

Cheers
Brian
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