UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Television and Video

Notices

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

Reply
 
Thread Tools
Old 4th Jan 2021, 6:22 pm   #1
Travellingwave
Pentode
 
Join Date: Jan 2021
Location: York, North Yorkshire, UK
Posts: 155
Default My first telly TV22

Hi
Just got myself a lockdown project in the form of a Bush TV22 Mk2. It will be my first attempt to revive a tv , have restored a couple of radios ( both Phillips), and deconsructed quite a few TVs in my youth.

Got the Bush via EBay

Appears to be in quite good nick to look at , no woodworm in the wooden bits and rubber insulation seems in pretty good condition

CRT heater has continuity and no shorts to other pins.

I notice the width control is fully to the right so maybe something had gone a bit adrift when last used

Just going through all the resistors at the moment , most seem ok , a bit high as expected, one or two quite a way off.

Will update as I go.
Travellingwave is offline   Reply With Quote
Old 4th Jan 2021, 6:59 pm   #2
mark pirate
Dekatron
 
mark pirate's Avatar
 
Join Date: Mar 2008
Location: Worthing, West Sussex, UK
Posts: 5,011
Default Re: My first telly TV22

Welcome to the forum, there is a wealth of information on here about the TV22.
I have restored quite a few of these iconic set's.

Before thinking of powering it up, it is well worthwhile to pass a current through the overwind of the line output transformer to drive out any moisture, as these are a common failure point on these sets.

Also check the resistance of the blocking transformer for open windings, these are also known to fail.

Good luck with the set, they are a good performer once overhauled.


Mark
mark pirate is offline   Reply With Quote
Old 4th Jan 2021, 8:58 pm   #3
Travellingwave
Pentode
 
Join Date: Jan 2021
Location: York, North Yorkshire, UK
Posts: 155
Default Re: My first telly TV22

Hi Mark.

I checked the blocking TX and it seems OK. I think this set has had dry storage judging by lack of worm in the wood. I am planning to dissolve the pitch on the LOPTX as suggested elsewhere.

Cheers.
Travellingwave is offline   Reply With Quote
Old 5th Jan 2021, 12:41 am   #4
Helder Crespo
Pentode
 
Helder Crespo's Avatar
 
Join Date: Sep 2019
Location: Crystal Palace, London, UK
Posts: 211
Default Re: My first telly TV22

Quote:
Originally Posted by Travellingwave View Post
Hi Mark.

I am planning to dissolve the pitch on the LOPTX as suggested elsewhere.

Cheers.
Hi
Yes, I totally recommend this method. As detailed by Argus25 and used by several forum members, this should be followed by varnishing (e.g., by dipping in marine spar or transformer varnish) or by spraying/coating with an anti-corona lacquer. I recently got a scrap chassis for parts where the LOPT was is a poor condition (paxolin former broken at the base, teared EHT contact, broken EY51 heater winding contact and clear signs of damp storage) but with all major windings surprisingly fine. By dissolving the pitch in white spirits - just be *very* careful with the ultra-thin (110 micron) wire connections in the overwind! - I was able to go from the condition shown in the first image to the clean and repaired state shown in the second image and the final varnished result. Judging by your description, your LOPT could be in a much better initial condition and the process should be straightforward, even though it can take up to two weeks in total.
In my first and only TV restoration so far (also a TV22 Mk2), the only element that failed after a few hours of operation was the LOPT, which had been left untreated and quickly developed a shorted primary (later rewound). I have a second set in even better original and untouched condition (it's an original "hybrid", with a Mk1 RF deck populated with EF91s and a Mk2 main chassis) and will give its LOPT the same treatment prior to using it on the set.
Good luck with your new project!
Helder
Attached Thumbnails
Click image for larger version

Name:	s-l1600.jpg
Views:	240
Size:	73.8 KB
ID:	223877   Click image for larger version

Name:	IMG_1972.jpg
Views:	238
Size:	65.0 KB
ID:	223878   Click image for larger version

Name:	IMG_2007.jpg
Views:	232
Size:	26.9 KB
ID:	223879  
Helder Crespo is offline   Reply With Quote
Old 5th Jan 2021, 7:21 am   #5
stevehertz
Dekatron
 
stevehertz's Avatar
 
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 5,204
Default Re: My first telly TV22

Watching with interest, my MK3 TV22 (EF80's) waits patiently (as it has for over 30 years in my possession) for restoration.
__________________
A digital radio is the latest thing, but a vintage wireless is forever..
stevehertz is offline   Reply With Quote
Old 5th Jan 2021, 8:55 am   #6
Travellingwave
Pentode
 
Join Date: Jan 2021
Location: York, North Yorkshire, UK
Posts: 155
Default Re: My first telly TV22

Thanks Guys
Yes my LOPT looks a bit more healthy than yours did!
What voltage/current have people used to dry the windings - I guess I can measure the resistance and apply ohms law.
Ordered a Hedgehog from Freya so have to get it working now.
Travellingwave is offline   Reply With Quote
Old 5th Jan 2021, 7:26 pm   #7
Travellingwave
Pentode
 
Join Date: Jan 2021
Location: York, North Yorkshire, UK
Posts: 155
Default Re: My first telly TV22

Some pics
Attached Thumbnails
Click image for larger version

Name:	F2519E90-7CB6-4C93-B498-26C65151F656.jpg
Views:	210
Size:	51.9 KB
ID:	223930   Click image for larger version

Name:	0CDBE77F-A37D-471C-BCE2-2BC93BC4EEE0.jpg
Views:	226
Size:	97.7 KB
ID:	223931   Click image for larger version

Name:	97255EF1-6B7A-4536-925A-420EB558BF13.jpg
Views:	222
Size:	102.5 KB
ID:	223932  
Travellingwave is offline   Reply With Quote
Old 5th Jan 2021, 8:13 pm   #8
Niechcial,Steve
Pentode
 
Join Date: Jan 2007
Location: Beckenham, London, UK.
Posts: 214
Default Re: My first telly TV22

Whilst it is not a bad idea to replace en masse all the wax paper caps in the timebases and power stages I would thoroughly recommend you don't change anything in the HF stages until you have run it up and seen the performance. I saw one of these recently where someone had changed all the RF caps together when most of them would probably have been OK, and the thing was so far off tune it picked up nothing and now needs complete realignment.
Niechcial,Steve is offline   Reply With Quote
Old 6th Jan 2021, 9:29 am   #9
Helder Crespo
Pentode
 
Helder Crespo's Avatar
 
Join Date: Sep 2019
Location: Crystal Palace, London, UK
Posts: 211
Default Re: My first telly TV22

Quote:
Originally Posted by Niechcial,Steve View Post
I saw one of these recently where someone had changed all the RF caps together when most of them would probably have been OK, and the thing was so far off tune it picked up nothing and now needs complete realignment.
Hi
I believe this can be a problem if you replace all the capacitors in the RF deck, including the moulded mica and the precision silvered mica ones (usually in good condition) in the tuned circuits, but all waxies (mostly used for decoupling) can in principle be replaced without affecting the alignment.
Helder

Last edited by Helder Crespo; 6th Jan 2021 at 9:30 am. Reason: typo
Helder Crespo is offline   Reply With Quote
Old 6th Jan 2021, 10:28 am   #10
mark pirate
Dekatron
 
mark pirate's Avatar
 
Join Date: Mar 2008
Location: Worthing, West Sussex, UK
Posts: 5,011
Default Re: My first telly TV22

I always leave the RF deck until the power supply & timebases have been recapped, when recapping the RF deck, the first caps to change are the heater decoupler caps.
These tend to short out and can burn out the valve heaters.

I have never had to change the mica caps in these, just the wax caps & electrolyticS.

See this thread on my set: https://www.vintage-radio.net/forum/...d.php?t=122108

As you can see, this set was giving excellent results until the LOPT died.
The set has since had a good replacement LOPT fitted & has been run for many hours without any issues.


Mark
mark pirate is offline   Reply With Quote
Old 6th Jan 2021, 10:31 am   #11
stevehertz
Dekatron
 
stevehertz's Avatar
 
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 5,204
Default Re: My first telly TV22

The golden rule with any vintage wireless or TV or even vintage hifi is don't change or even move ceramic disc and mica caps in tuner sections. They're highly unlikely to be problematic and more damage, extra work and heartache will ensue if they're messed with. Blow the area out or use a light brush to remove dust build up.
__________________
A digital radio is the latest thing, but a vintage wireless is forever..
stevehertz is offline   Reply With Quote
Old 6th Jan 2021, 12:30 pm   #12
Helder Crespo
Pentode
 
Helder Crespo's Avatar
 
Join Date: Sep 2019
Location: Crystal Palace, London, UK
Posts: 211
Default Re: My first telly TV22

I totally agree with Mark and Steve. In my TV22 Mk2, the only mica caps I had to change were the line synch and line feedback caps (100pf and 300pf respectively on the Mk2 - one of them is "hidden" under the small tagboard in the main chassis). This was done to solve some remaining line trigger jitter, which was tracked down to low-ESR in those caps (the HT smoothing electrolytics having been replaced already). I replaced them with 1000V-rated dipped silver mica caps. Below are two screen images, before and after the replacement. Neverhtless, I believe that tackling these kind of issues is something you can do once you have your set running reasonably well, i.e., at a later stage of the restoration.
Helder
PS - this thread pointed me in the right direction: https://www.vintage-radio.net/forum/...sformer&page=2
Attached Thumbnails
Click image for larger version

Name:	IMG_0068 (1).jpg
Views:	152
Size:	87.8 KB
ID:	223966   Click image for larger version

Name:	IMG_1253 (1).jpg
Views:	157
Size:	55.4 KB
ID:	223967  

Last edited by Helder Crespo; 6th Jan 2021 at 12:41 pm. Reason: added link
Helder Crespo is offline   Reply With Quote
Old 6th Jan 2021, 1:12 pm   #13
beery
Heptode
 
beery's Avatar
 
Join Date: Jun 2006
Location: Ware, Hertfordshire, UK.
Posts: 855
Default Re: My first telly TV22

Hi Travelling wave.
Welcome to the world of vintage TV collecting.
The TV22 isn't the easiest set to start on, but it is easy to get to most of the components and many people on this forum have had experience with them.

On most sets I would advocate the idea of replacing one waxie at a time and powering up between each change to learn the symptoms that each fault gives.
However, due to the fragile nature of the frame blocking oscillator transformer in this set, I would recommend replacing all the waxies in the frame timbase before you power up. Also do test or replace the ECL80s in this set. If the line oscillator triode fails it will be game over for the PL38 and could kill the LOPT.

Some pointers from me,
The main smoothing capacitor can usually be reformed, but the 16uF axial underneath the deck will probably need replacement.
The A1 supply smoother, which I think is 0.1uF 500v is hiding underneath the tag board on the underside of the chassis. Replace this with a 630V cap, and replacing this before you test can prevent the metrosil (a vdr, a red oxide coloured 10p sized disc).

Dry out the LOPT overwind by passing a small DC current through it. There are several threads that mention how to do this.

Also before you do initial tests, cut connection to the Xcap which lives near the dropper resistor, also cut the huge waxie at the front of the chassis. These should be replaced later, but are not required for basic tests.
Also, you may find that the heater decouplers start to fail. Temporarily cut each one out of circuit as they fail, to enable you to get the time bases working properly first and then replace them later.
I've got loads of other advice, but I will stop there for now.
Good luck with it.

Cheers
Andy
beery is offline   Reply With Quote
Old 6th Jan 2021, 3:28 pm   #14
Travellingwave
Pentode
 
Join Date: Jan 2021
Location: York, North Yorkshire, UK
Posts: 155
Default Re: My first telly TV22

Hi
Thanks for all the advice - will have to read it all more carefully tonight.

Just got the LOPTX out , all windings have approx the correct resistance so fingers crossed. Does look to have been quite hot in its life

It’s gone into a tub of white spirit to get rid of the old pitch
Attached Thumbnails
Click image for larger version

Name:	26EA991C-BE90-407E-A799-5FBC7EC60F12.jpg
Views:	117
Size:	73.9 KB
ID:	223982  
Travellingwave is offline   Reply With Quote
Old 7th Jan 2021, 10:50 am   #15
Travellingwave
Pentode
 
Join Date: Jan 2021
Location: York, North Yorkshire, UK
Posts: 155
Default Re: My first telly TV22

Got me a hedgehog
Thanks Freya great service

I was contemplating building one but decided having an untested tv and untested hedgehog was asking for trouble

I followed the thread on its creation with awe- fantastic piece of work. Have 30 years experience with industrial programmable logic controllers but never done anything with FPGA - think I will have to have a play sometime
Attached Thumbnails
Click image for larger version

Name:	441EA0A5-FFF0-44C4-A8B6-CE439A5A8C2D.jpg
Views:	104
Size:	84.6 KB
ID:	224035  
Travellingwave is offline   Reply With Quote
Old 7th Jan 2021, 10:54 am   #16
Travellingwave
Pentode
 
Join Date: Jan 2021
Location: York, North Yorkshire, UK
Posts: 155
Default Re: My first telly TV22

After just a night in white spirit the pitch on the LOPT is mostly gone. Will give it a bit longer then start drying it out

What’s the chance the EHT lead is still fit for purpose? The rubber seems fine
Attached Thumbnails
Click image for larger version

Name:	96275DE2-1D7E-4F5C-B21F-93751540D213.jpg
Views:	125
Size:	96.8 KB
ID:	224036   Click image for larger version

Name:	F31CA64E-8041-4AAB-B5C1-6C30B9BB0E72.jpg
Views:	113
Size:	70.1 KB
ID:	224037  
Travellingwave is offline   Reply With Quote
Old 7th Jan 2021, 11:08 am   #17
stevehertz
Dekatron
 
stevehertz's Avatar
 
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 5,204
Default Re: My first telly TV22

Re the LOPT, some say pass a small DC current through it, others say remove the pitch etc. Which is best? pros and cons?
__________________
A digital radio is the latest thing, but a vintage wireless is forever..
stevehertz is offline   Reply With Quote
Old 7th Jan 2021, 12:08 pm   #18
Helder Crespo
Pentode
 
Helder Crespo's Avatar
 
Join Date: Sep 2019
Location: Crystal Palace, London, UK
Posts: 211
Default Re: My first telly TV22

Quote:
Originally Posted by stevehertz View Post
Re the LOPT, some say pass a small DC current through it, others say remove the pitch etc. Which is best? pros and cons?
From my experience, removing the pitch with white spirit and dipping in varnish (while still wet from the white spirit) will result in deep impregnation of the varnish in all windings, and not just the overwind. And TV22/TV24 LOPTs are known to fail due to o/c in the primary section. I believe that Ed Dining (who rewinds LOPTs) has posted here that the thin and aged paper insulation can become carbonised, hence causing the problem. Also, if you remove the pitch and recoat, this should prevent water from getting into the windings. I guess that if a set is used regularly it should be fine to just pass a current prior to first use, but a stored "cold" set will eventually gather moisture unless its original and usually cracked (hence non-effective) pitch coating is replaced by either another pitch coating or varnish.

As for the EHT cable, the one in my first set has been replaced for safety during the rewinding of the LOPT, which had developed the dreaded o/c primary after a few hours of steady operation. Prior to that, the original cable and insulation seemed to work fine.
Helder Crespo is offline   Reply With Quote
Old 7th Jan 2021, 12:16 pm   #19
Helder Crespo
Pentode
 
Helder Crespo's Avatar
 
Join Date: Sep 2019
Location: Crystal Palace, London, UK
Posts: 211
Default Re: My first telly TV22

Quote:
Originally Posted by Travellingwave View Post
After just a night in white spirit the pitch on the LOPT is mostly gone. Will give it a bit longer then start drying it out

What’s the chance the EHT lead is still fit for purpose? The rubber seems fine
Your LOPT is looking great. I see no signs of previous overheating or rust from damp storage. Just be *very* careful with the thin overwind connections (arrowed). If you let the white spirit work its way for some more time you will end up with a nice and clean LOPT with intact connections.
Attached Thumbnails
Click image for larger version

Name:	Untitled.jpg
Views:	128
Size:	94.7 KB
ID:	224046  

Last edited by Helder Crespo; 7th Jan 2021 at 12:20 pm. Reason: corrected arrows in the image
Helder Crespo is offline   Reply With Quote
Old 7th Jan 2021, 3:09 pm   #20
Travellingwave
Pentode
 
Join Date: Jan 2021
Location: York, North Yorkshire, UK
Posts: 155
Default Re: My first telly TV22

Thanks Helder
So is it best not to heat the lopt after treating with white spirit but rather leave it to help with varnish impregnation?
Travellingwave is offline   Reply With Quote
Reply

Thread Tools



All times are GMT. The time now is 2:21 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


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