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Pye CTL58F

 
Black & White Television plus Standards converters
Last Post by LSmith 4 months ago
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 LSmith
(@lsmith)
Posts: 64
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My Pye CTL58F is the set shown sitting on top of the very similar CTL58VS in my avatar photo. These sets were both kept in the loft by my dad and I restored the CTL58VS a couple of years ago. My 58F has lost its two main speakers, the wooden speaker mounts and grilles and its back cover. When switched on it always used to show a faint raster which would then fade away after a couple of minutes, so apart from replacing a few random capacitors around 30 years ago as a teenager I’ve never really bothered doing anything with it as I assumed the LOPT was faulty. Applying a signal during the brief period when something was visible on the CRT also showed that the vision signal wasn’t making it through.

A few weeks ago I thought I’d have a go at drying the LOPT out by passing DC through it just in case this made any difference, and have been very surprised by the results!

I passed around 90mA through the whole LOPT for 5 days which made the EHT overwind warm to the touch. I noticed that there are a few bubbles in the pitch on the overwind, so it must have got quite hot at some point in the past possibly due to the absorbed moisture boiling off.

Before powering up I replaced the boost reservoir and a nearby wax capacitor which is in the same circuit. When first switching on, I had to switch off quickly as one of the wax caps in the 3rd vision IF stage started fizzing. This is C19 which is not shown in the manufacturer’s service data, but is shown between G1 of the EF80 IF amp valve and chassis on the diagram in the R&TVS book. Once this had been replaced, we had fireworks in the EF80 during warmup so I quickly switched off again. When switching on again with a substitute EF80 in place there were no fireworks and when I tuned into a signal a very folded over test card appeared on the screen. The image did not fade out during 10 minutes or so of operation so things were looking better.

I then replaced the coupling capacitor to the grid of the line output valve and did the same for the sound output valve. In terms of my frame issue, a good candidate for replacement appeared to be C81 which feeds the primary of the frame output transformer via a pair of 18k resistors. After replacing this and adjusting the linearity controls I had a very nice well proportioned test card. I get a dim image at minimum brightness, and a very bright image with no defocusing with the brightness fully advanced. After 10 minutes or so operation the EHT overwind only feels slightly warm to the touch, so I’m hopeful that the LOPT will hold up when the set is used for longer periods. This does appear to be a low mileage set, as the area around the LOPT is remarkably clean.

Adjusting the contrast control results in a distorted image and loss of frame hold at one end of the control, so I will continue recapping the set and see what improvements result. The main electrolytic runs cool, but has a little discharge underneath, so will have to be replaced next.  I just need to keep an eye out for a scrap set now so I can obtain those missing cabinet parts!

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Posted : 23/02/2025 9:46 pm
Topic Tags
Pye CTL58F 405 line TV repair Black and white
 Petedox
(@petedox)
Posts: 20
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A nice write up, glad you saved the LOPT (so far!). 

 
Posted : 24/02/2025 10:46 am
 irob2345
(@irob2345)
Posts: 808
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Yes that was a relatively painless re-boot!

Did you mean G2 of the EF80 (aka 6BX6)?

Do consider the turps boil and poly soak trick for the LOPT.

 
Posted : 25/02/2025 8:36 am
 malcscott
(@malcscott)
Posts: 1565
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The crt looks very good.

 
Posted : 25/02/2025 3:29 pm
 LSmith
(@lsmith)
Posts: 64
Trusted Member Registered
Topic starter
 

@irob2345 it's between an 8.2k resistor which is connected to G1 and the chassis, I should have been clearer in my description. I've included a snip of the relevant part of the circuit.

V5 cct snip

@malcscott yes the LOPT enclosure and the area underneath it only has a light coating of grime and/or dust, so it looks to be a low mileage set.

 
Posted : 25/02/2025 8:31 pm
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Topic Tags:  Pye CTL58F (1) , 405 line TV repair (3) , Black and white (3) ,

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