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Old 18th Dec 2022, 12:28 am   #21
sexton_mallard
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Default Re: Pilot 23/625 TV

I got back to this interesting set armed with a new EY86 at last! Upon switch on I was rewarded with a healthy heater glow in the EY86, the rustle of static and a nice loud 625 line whistle which my middle aged ears could clearly make out. A very dim raster appeared which responded to the height and width controls but no diffrerence could be made from the contrast and brightness controls.

I let the set run for 5 minutes but then noticed the PL36 was beginning to red plate and switched off with a very bright frame collapse and bright dot. Next move is some voltages as I have a gut feeling the dull picture problem may not neccesarily be a tired CRT...
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Old 20th Dec 2022, 12:20 am   #22
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Default Re: Pilot 23/625 TV

Tonight I replaced a couple of caps in the line stage, HT was around 245v and A1 400V. scratching the end of a clip lead connected to the CRT cathode produced some promising splodges and dots. shorting the cathode to grid produced a bright picture shown below. letting the set idle for 20 minutes did not show any distressed components and the overwind bobbin was nice and cool.

This set has the best old telly smell! A luxurious bouquet of warm paxolin, wax and plywood and no zizzy smell of corona ozone either. I lost the replacement PC97 valve but for now I need to obtain a VHF PAL modulator and another PC97. The CRT at least is not totally dead and seems to be waking up. Its heater is now joined up once again in the heater chain and the CRT transformer made redundant.
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Old 8th Jan 2023, 1:10 pm   #23
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Default Re: Pilot 23/625 TV

More improvements with more frame caps replaced. The PC97 valve turned up in the end but I won't be back to this set for a few months hopefully armed with a VHF modulator.
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Old 9th Apr 2023, 7:07 pm   #24
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Default Re: Pilot 23/625 TV

I have returned to this set and armed with a VHF modulator and the PC97 installed, I made sure it was set with a 6MHz sound offset. I now have static on at least 3 of the channels on the set. Channel A and C. Some activity can be seen with a bar generator built into the HDMI adaptor.

A test on a modern small 4 inch TV proves the modulator is working to VHF Channel C with the Pilot set on the same channel. A wiggle of the valves on the top chassis deck was tried but now the line oscillator has stopped running! Doh! Watch this space...
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Old 9th Apr 2023, 9:39 pm   #25
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Default Re: Pilot 23/625 TV

Hi Dom,

Great to see this early 625 line VHF Irish TV coming to life again, a rare beast indeed.
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Old 10th Apr 2023, 10:38 pm   #26
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Default Re: Pilot 23/625 TV

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Originally Posted by linescan87 View Post
Hi Dom,

Great to see this early 625 line VHF Irish TV coming to life again, a rare beast indeed.
Thanks John Joe!

Today I concentrated from the Aerial socket backwards. I cleaned the contacts in the tuner and upon checking the tuner valves I find a PCF805 in place of a PCF86. Is this a sensible substitute?

The effect I am seeing at first appears to be the line frequency is way off but I can hear a 16khz whistle and the frame running at approx 25fps to my ears. After a few seconds there is a fade to white dots from a affect where the tone bars do appear in the distorted picture if that makes sense. This effect can be repeated by switching the channel back and forth. I will carry on checks in the meantime but this is somewhat an estimate as I don't have the correct circuit diagram.
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Old 11th Apr 2023, 6:50 am   #27
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Default Re: Pilot 23/625 TV

The set looks sensitive enough.
It looks like it it is somewhat off tune. Try the fine tuner first. You may need to tune the oscillator coil which would be towards the front of the tuner.
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Old 11th Apr 2023, 9:44 am   #28
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Default Re: Pilot 23/625 TV

I can't help you with the fault, but I can comment on the tube heaters. The tube heaters would have been run in series with the valve heaters. If the tube heaters were at the end of this train, then they would more than likely be under run, especially in the Winter where the load from the national grid would have been at it's highest on cold Winter evenings causing a lower voltage to domestic dwellings. Tubes running at lower heater voltages would show low emission. The fitting of a heater supply transformer to a TV would restore the quality of the picture. Sometimes there was no need to use the extra percentage tap.
The heater transformer on the higher voltage tapping was also used to give extra life to low emission crts that had just aged. A lot cheaper than a tube replacement.

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Old 11th Apr 2023, 12:01 pm   #29
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Default Re: Pilot 23/625 TV

These VHF turret tuners (made by Thorn/Ferguson in the UK under an American patent licence) usually have a small paper label stuck on them with the specific type, which is usually MTxx, where xx is a number (MT = Miniature Turret). I see from an earlier post in this thread, that your tuner has a label stating MT5A/4E.

From the look of the soldered joints of the individual wires to the tuner's feedthrough capacitors, I'd say it has been removed at some point in the past and perhaps a different MTxx type fitted to the original....?

These VHF turret tuners (made by Thorn/Ferguson in the UK under an American patent licence) usually have a small paper label stuck on them with the specific type, which is usually MTxx, where xx is a number (MT = Miniature Turret). The earliest MT tuners used a PCF86; later tuners used a PCF805/30C18. The base connections are very different between a PCF805 (= 30C18 in Mazda nomenclature) and a PCF86.

A way to check which type of valve the mixer/oscillator should be, would be to see which pin has the mixer pentode's g2 feed from the HT line (30C18 = pin 2 and 22k; PCF86 = pin 9 and 18k). I can see a likely looking 22kOhm 0.5W 10% carbon composition resistor connected to a pin of the mixer/oscillator valve but can’t determine which pin it is from the photo.
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Old 11th Apr 2023, 11:55 pm   #30
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Default Re: Pilot 23/625 TV

Thank you all for all the great information provided. Looking more closely it appears the 22k resistor is on pin 2 unless I am mistaken, so it appears the presence of a PCF805 is correct.
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Old 12th Apr 2023, 10:04 pm   #31
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Default Re: Pilot 23/625 TV

This evening I fed a proper video signal via a PC with sound to the set via HDMI. Sound is reproduced in good quality and this set is furnished with bass and treble controls! This tells me the tuner is basically OK and I have a problem in the video IF/detection or maybe the line timebase is way off... No change with different attenuation of the RF signal, channel or twiddling the fine tuner.
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Old 13th Apr 2023, 6:54 am   #32
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Default Re: Pilot 23/625 TV

What a nice, clean set. I’m jealous!
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Old 13th Apr 2023, 8:39 am   #33
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Default Re: Pilot 23/625 TV

If you compare the image between aerial in and out, you will see that everything is getting through.
what happens when you adjust the line (horizontal) hold?
It still looks as if the oscillator is off tune. (tune)
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Old 23rd Apr 2023, 9:36 pm   #34
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Default Re: Pilot 23/625 TV

Quote:
Originally Posted by Rich Woods View Post
What a nice, clean set. I’m jealous!
Hi Rich. Thanks! The tuner is very clean which hints to it being replaced especially as there is no red QA paint dots on the soldered connections. The rest of the set has the usual sooty dust which I will clean properly once the set is basically debugged and running OK.

Quote:
Originally Posted by williamsunique View Post
I can't help you with the fault, but I can comment on the tube heaters. The tube heaters would have been run in series with the valve heaters. If the tube heaters were at the end of this train, then they would more than likely be under run, especially in the Winter where the load from the national grid would have been at it's highest on cold Winter evenings causing a lower voltage to domestic dwellings. Tubes running at lower heater voltages would show low emission. The fitting of a heater supply transformer to a TV would restore the quality of the picture. Sometimes there was no need to use the extra percentage tap.
The heater transformer on the higher voltage tapping was also used to give extra life to low emission crts that had just aged. A lot cheaper than a tube replacement.

Paul.
Thanks Paul. Once I have the set running OK I will run the CRT heater again from the 6.3v CRT heater transformer and compare brightness. The back of the set states 220V 50c/s (normal on Irish made sets from what I've seen) but the voltage dropper setting is on 245V so I do need to check supply voltages. There are loads of duff caps to replace (one by one..) once I return to this set in a few weeks which could also affect performance. My gut feeling the CRT will be tired but will give an acceptable picture (hopefully).
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Old 15th Jul 2023, 11:37 pm   #35
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Default Re: Pilot 23/625 TV

Detail of the top chassis of this single standard set. Some sickly looking caps near the audio stage!
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Old 16th Jul 2023, 11:30 am   #36
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Default Re: Pilot 23/625 TV

Please forgive my "thickness". I was a tv engineer for many years and worked for Sony and LG. I now am retired and thick, dementia and stroke. Was this a badge name set? I recall the make but can't remember their sets. Thanks anyone. Tony Walker
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Old 16th Jul 2023, 12:33 pm   #37
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Default Re: Pilot 23/625 TV

Quote:
Originally Posted by toshiba tony View Post
Please forgive my "thickness". I was a tv engineer for many years and worked for Sony and LG. I now am retired and thick, dementia and stroke. Was this a badge name set? I recall the make but can't remember their sets. Thanks anyone. Tony Walker
Copied and pasted from an earlier post in this thread:

The chassis is clearly of Ferguson/Thorn origins, as has been said above, with a remarkable resemblance to the UK's Marconiphone VT161 and the New Zealand set. Thorn must have licensed the design to overseas manufacturers, or even sold kits for assembly overseas.

The valve position sheet has a Ferguson part number on it, as does the frame output transformer.

Thorn acquired Ultra Radio & Television Ltd from Ultra Electric Ltd, in 1962 and that included the Pilot (UK) company, which Ultra had bought a few years earlier.

In the 1950s, Pilot sets were manufactured by Brownlee Bros Ltd., Molesworth Street, Dublin - under licence from Pilot Radio Ltd, London.

Later in the 1960s, Pilot branded sets were still being made/assembled in the Republic of Ireland, by Brownlee Brothers Ltd (by then, listed as a Thorn subsidiary in at least a Thorn Electrical Industries Ltd annual report and accounts publication). I have an operating instructions booklet for a Pilot model DS-1400 set based on the Thorn 1400 chassis. I also have a Pilot branded service manual for the (Thorn) 900 chassis, issued by Brownlee Brothers.
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Old 16th Jul 2023, 1:26 pm   #38
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Default Re: Pilot 23/625 TV

I followed TCE\Thorn fairly extensively in the 60s\70s. From the 850 range to the later TX100's. This one crept through, interesting looking set, this one. Looked quite feature packed e.g. sep. bass and treble, thanks for info.
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Old 7th Aug 2023, 8:48 pm   #39
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Default Re: Pilot 23/625 TV

Slowly getting there....a few more red and black electrolytic caps and then resistor checks. The picture is shunted over to the right with the V and H hold more or less to the end of their settings.
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