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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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15th Jan 2017, 3:00 pm | #1 |
Octode
Join Date: May 2003
Location: Belper Derbyshire
Posts: 1,909
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Bush TV62 progress
I bought this set recently and decided to have a go at it as I was pulling my hair out over the VT4.
On checking it over and winding it up on the variac there was lots of smoke from the droppers at only a relatively low mains voltage. I found that someone in the distant past had been playing with the power supply and HT was being fed to the heater chain and AC direct to the smoothing cap!! There was a 2.2K wirewound resistor and a huge wax capacitor in series between the HT and chassis and this had gone O/C in the past and both were removed for replacement. It looks as the set has had a hard life as most of the valves were replacement types and even these were quite blackened. The base glass of the CRT had a few patches of staining on it and I was wandering if this CRT had any emission left!! The tuner was very stiff changing from band I to band III so the operating plungers and slide switch were carefully cleaned up and lubricated and now operates smoothly. Once this was all sorted out and the crumbly insulation to the scanning coils was replaced whilst I was there I tried again and got the valves to light and a little HT but nothing else. The cables on the multi-plug to the RF chassis was replaced as this was crumbling as well and I replaced the PY82's and the line output and efficiency diode. This time there was plenty of HT but no line whistle. I then saw a reflection of light from the front of the set and noticed a horizontal line that was slowly shrinking in width proving that the line output stage was working but I could not hear it. On replacing many wax capacitors around the line and frame stages a full raster was produced and I could just hear the line output stage. It was running at a much higher frequency than it should. This turned out to be the line hold control pot which should be 1 Meg but someone had replaced it with a 220K ohm one. I found a similar looking 1 Meg pot in the loft and when fitted the line frequency could be adjusted so it locked. The picture suddenly went dim followed soon after by a spluttering noise underneath the chassis. This turned out to be another wax cap between the HT and the heaters giving up. This was soon removed and a new one installed and service resumed More wax capacitors changed and on connecting the aurora test card C was visible and once the linearity, height, contrast picture shift ECT. had been twiddled the image is very clear. I watched a BVWS DVD for some time and it gave a good account though the frame hold is still a little critical and the picture rolls occasionally. There is still plenty to do as all of the wiring between the mains switch and droppers needs replacing. There are still a few wax capacitors that need changing which should improve the sets stability. The Bakelite case is in good condition and only needed a polish to get it to look good. Christopher Capener
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Interests in the collection and restoration of Tefifon players and 405 line television |
16th Jan 2017, 7:55 pm | #2 |
Dekatron
Join Date: Jun 2009
Location: Staffordshire Moorlands, UK.
Posts: 5,263
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Re: Bush TV62 progress
that was quick! Sometimes these interim successes help restore the enthusiasm for the more difficult repairs that get cast aside for a while.
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Kevin |