UK Vintage Radio Repair and Restoration Discussion Forum

UK Vintage Radio Repair and Restoration Discussion Forum (https://www.vintage-radio.net/forum/index.php)
-   Vintage Television and Video (https://www.vintage-radio.net/forum/forumdisplay.php?f=37)
-   -   Pye CTM4. (https://www.vintage-radio.net/forum/showthread.php?t=146572)

FERNSEH 15th May 2018 10:02 pm

Pye CTM4.
 
2 Attachment(s)
Bought this Pye Continental CTM4 at the NVCF.
The cabinet is a bit rough and examination this evening reveals that the loudspeaker is missing. Also missing are the tuner valves, PCC84 and PCF80. The two PY82 HT rectifiers are missing. Way back in 1966 I replaced the PY82s with a pair of PY81s, a quick fix solution at the time because I didn't have any PY82s in stock.
The electrolytics are dated Feb/Mar 1956. Curiously, the AW36-21 CRT is date stamped R7J, late 1957 or is it 1967?
The chassis is a slightly modified version of the late production VT4. The IFs will be the BREMA values, 34.65Mhz vision and 38.15Mhz sound.
Like the VT4 the tuner is attached to the left side of the cabinet.

DFWB.

Lloyd 1985 15th May 2018 10:14 pm

Re: Pye CTM4.
 
I recognise this set! I think I was stood next to you when you bought it, I bought the PYE sunrise radio off the same stall, if I’d realised it was you I’d have said hi!

Regards
Lloyd

linescan87 15th May 2018 10:24 pm

Re: Pye CTM4.
 
Glad to see you and the set got home safe, time to get cracking!

Cheers, John Joe.

MonochromeMarc 15th May 2018 10:26 pm

Re: Pye CTM4.
 
Hi David,

I looked at that set too but resisted the temptation, pleased it's ended up in capable hands though. ;)

By the way, how did I fail to spot you at the NVCF ? Now there's a real mystery. ;D

Marc.

FERNSEH 15th May 2018 10:37 pm

Re: Pye CTM4.
 
Quote:

By the way, how did I fail to spot you at the NVCF ? Now there's a real mystery.
Hi Marc,
Remember the Monty Python sketch of "not being seen"?

DFWB.

mark pirate 16th May 2018 6:31 am

Re: Pye CTM4.
 
Quote:

Originally Posted by FERNSEH (Post 1043843)
The cabinet is a bit rough and examination this evening reveals that the loudspeaker is missing.

I bought two Pye sets from different sellers, both had their speakers missing, I wonder if there was something special about the original R&A speakers?

I look forward to seeing the CTM4 being bought back to life, lets hope the CRT & LOPT are OK.
:beer:
Mark

Jac 16th May 2018 8:36 am

Re: Pye CTM4.
 
David,

I have two PY82s for you.

Jac

ukcol 16th May 2018 8:47 am

Re: Pye CTM4.
 
Quote:

Originally Posted by FERNSEH (Post 1043843)
The chassis is a slightly modified version of the late production VT4.DFWB.

I remember when I was an apprentice being impressed with the picture quality of the VT4. No doubt your set will give a very good picture when you have finished it.

FERNSEH 16th May 2018 9:01 am

Re: Pye CTM4.
 
Jac wrote: "I have two PY82s for you."

Good morning Jac, many thanks for your kind offer, these valves are always welcome. PM sent.

Before any servicing work is done to this set the line output transformer must be warmed up by passing a current of about 20mA through the EHT overwind and primary. This procedure has been proven to be effective for driving out any moisture in the windings.
It's fifty-two years since I serviced one of these sets.

DFWB.

beery 16th May 2018 10:23 am

Re: Pye CTM4.
 
Quote:

Originally Posted by FERNSEH (Post 1043853)
Remember the Monty Python sketch of "not being seen"?

What actually happened is that after purchasing the telly, the men in white coats came and took David away.
Sorry David, we saw you hanging around the PYE and felt duty bound to call the clinic. It's for your own good, you will thank us in the end :-D

Unfortunately we were too late to prevent the purchase of the PYE though :(

Cheers
Andy

FERNSEH 16th May 2018 11:10 am

Re: Pye CTM4.
 
Hi Andy,
Don't worry, I managed to escape and the set is safe in my workshop in Geordieland.

DFWB.

MonochromeMarc 16th May 2018 2:48 pm

Re: Pye CTM4.
 
So, how long before we get "Begin The Beguine" singing from the Pye then David ? ;)

If it's the same loudspeaker as the VT4 I think I may have one going spare, I'll try and have a look for it later.

Marc.

Heatercathodeshort 16th May 2018 5:14 pm

Re: Pye CTM4.
 
I desperately tried to keep David away from this backless wreck. I even covered it over with an old raincoat but it just attracted more attention due to the curiosity factor.

It's only a common as muck VT4 wearing a posh frock David. It will probably need a set of scan coils, a LOPT and that's after you have changed 231 leaking waxies and 27 diodes.

The loudspeaker has gone to a better home such as a lovely Ekco T231 and the pair of PY82s to a deserving Philips.

I have no doubt it will end up in the retirement home for television receivers with 'trench feet'. Anyhow I wish you good luck with it and if you are stuck for the valves, I have some good spares. My head shakes..John.

Tractionist 16th May 2018 6:53 pm

Re: Pye CTM4.
 
We must all try to be 'understanding' ...... this is his idea of 'down-sizing' !!

FERNSEH 16th May 2018 7:07 pm

Re: Pye CTM4.
 
HKS wrote: It's only a common as muck VT4 wearing a posh frock David. It will probably need a set of scan coils, a LOPT and that's after you have changed 231 leaking waxies and 27 diodes.
Hi John,
it's such an attractive looking set that I reckon it has be restored. Good looking sets like this don't appear very often. I've always liked the Pye Continental series including the CTM17 and the 21" version, the CTM21.

Testing the CTM4. Found two PY82 HT rectifiers diodes and fitted the correct valves in the tuner. Quite a few problems with the heater chain not helped much because some wires in the chain had been snipped off.
Been using a RS components RS14 digital multi-meter for fault finding, its a rather disappointing instrument but for 24 what can you expect?
Also there is evidence of some creative '50s and 60s servicing solutions to sort out.
A suitable elliptical loudspeaker has been found.

DFWB.

FERNSEH 16th May 2018 9:04 pm

Re: Pye CTM4.
 
1 Attachment(s)
No full service manual issued for the CTM4. Use the service manual for the late production VT4 with this modification sheet.

DFWB.

FERNSEH 19th May 2018 10:37 am

Re: Pye CTM4.
 
The Pye CTM4 is connected to the main via the variac. Supply set to 200 volts because the mains dropper resistor is open circuit and is at present shorted is out.
The 250mA line output stage fuse removed for the preliminary tests.
Oscilloscope analysis reveals the line and frame oscillators are working delivering sawtooth drives at the correct frequencies to the grids of the output valves.
Sound output stage working but no activity from the tuner. The HT supply to signal stages was found to be missing, the 200ohm decoupling resistor R45 was found to be disconnected from it's anchor tag.
Now signals can be heard and after turning down the sensitivity control a video waveform is present at the video detector load resistor.
The video amplifier stage is not working so that stage will be next for testing.

Will report back my findings later today.

DFWB.

FERNSEH 19th May 2018 2:42 pm

Re: Pye CTM4.
 
In fact the fault in the video amplifier was a simple one. The 15Kohm anode load resistor was short circuited to the centre spigot of the valveholder. Repositioning the component effected a cure.
40 volts of active video + syncs is present across the load resistor of the video cathode follower.

Assuming the CRT is OK this set will display a well contested picture.

The sync separator is functioning correctly. High amplitude negative going sync pulses are present at the anode of the sync separator valve.
The interlace filter diodes will need replacing.

DFWB.

Heatercathodeshort 19th May 2018 8:21 pm

Re: Pye CTM4.
 
Nice procedures David but does it produce any EHT! I am gagging for an answer. John.

FERNSEH 19th May 2018 10:09 pm

Re: Pye CTM4.
 
"Nice procedures David but does it produce any EHT! I am gagging for an answer." John.
Hi John,
'fraid not. It's most likely the line output transformer is faulty. No trace of a spark at the anode of the EY51 EHT rectifier valve.
The PL81 is passing excess current and that's likely the reason why the 250mA timebase fuse was found to be blown.
The scan coils have been disconnected because back in the old days along with the line output transformer the coils were another source of trouble in the V4, VT4 and CTM4.

DFWB.


All times are GMT. The time now is 6:33 pm.

Powered by vBulletin®
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Copyright ©2002 - 2021, Paul Stenning.