Introduction and questions re TV22 - Page 3 - UK Vintage Radio Repair and Restoration Discussion Forum

Geoff 555 · 30th Jan 2008, 10:40 pm

John thank you for your reply and the invitation, if I am around West Sussex then I will take you up on your generous offer.
The matter has now been decided !!!!!! I had another lean and tap session and there was a fair old flash and after I had come down from the ceiling found that the heater was most definitely O C.
Another tube will be found.
And another question , the scan coils are very well stuck to the tube, what is the best way to remove them without damage please.

Many thanks John.

Geoff.555.

Heatercathodeshort · 31st Jan 2008, 9:53 am

Hello Geoff,
Its very rare for a Mullard tube heater to go O/C so I guess it was in a poor state by the sound of it. Tubes are around but unfortunately due to the cult status of the set tend to be a bit of a premium. The Mazda CRM93 used in the Ekco TMB272 can be used almost without modification but it seems such a pity to break one of these brilliant receivers for the CRT. In my opinion it is far more interesting than the TV22 but there you go.
I think you will find if you run the set for an hour or so before you attempt to remove the CRT the scan coils shoild be fairly easy to remove. You can S/C the tube heater pins to maintain chain continuity.
No need to fit a resisitor in its place for the limited time you are going to run the set. Regards, John.

Geoff 555 · 6th Feb 2008, 7:57 pm

Thank you again gentlemen, the scan coils came off in the end.
To cut a long story short, for the time being, picture can only be obtained with the contrast turned fully up, if the control is turned down, wiper just off the end stop then it kills the picture, raster. The cut off is very sudden and if I am very careful and slow with the control I can see that the line lock is lost. before the screen goes blank. The control is OK and has been cleaned.
Top section PZ 30 etc. Bottom section EL80.
All recapped. Any ideas what to go for?
Cheers.
Geoff.

beery · 6th Feb 2008, 8:00 pm

Hi Geoff,
disconect one end of the brightness control and measure its value end to end. It should be 50K, but they often go O/C midway causing some very odd symptoms.

Cheers
Andy

Geoff 555 · 6th Feb 2008, 10:09 pm

Hello Beery have measured and it comes out at 51.3K. Tomorrow I will see if there are any more symptoms.
Thank you.
Cheers.
Geoff.

PJL · 7th Feb 2008, 11:35 pm

Hi, I have been watching the thread to encourage me to have a go at my first 405, a Pye I have had for ages. All was doom and gloom as the heater was open-circuit - next post you have a picture. Do let us know what happened?

beery · 8th Feb 2008, 12:27 pm

Hi Geoff,
hard to say without seeing the result.
Could be...
1.A fault in the video amplifier, so check resistance values around here. Wrong bias here can cut off the tube and cause sync crushing.

2.A fault in the line oscillator circuit. If the line timebase is really out of range then the EHT may be way off as well.

Cheers
Andy

Geoff 555 · 8th Feb 2008, 9:46 pm

OK everyone, it's time for an update and explanation.
Set 1.
As in all the questions up to the last couple. The tube was completely U/S. Upon further investigation, which I didnt want to bore you with, the more I looked the more I found and came to the conclusion that in the past it had been well and truly got at. Choke linked out, capacitors connected to places that they shouldnt have been etc. The state of the LOPTx finally had me looking in a different direction. Melted pitch and exposed windings and green mould, not a pretty sight.

Set 2.
I had the chance to buy a tube that was good and upon inquiring found that I could have a chassis with it. This turned out to be in a much better condition than the original. So ------- .Questions about the brightness etc. The instability and whistling was down to a EF80 that although testing OK could be made to stop and start playing about simply by giving it a tap. Sorted.
The brightness/contrast problem is still there but is not as bad, still investigating that.
I have the chance of a tube that will fit with a change of base and be, at least, watchable, this will be fitted to the original chassis and this will be restored over a period of time. This will give me a chance to gather the various parts that will be needed.
There are two radio's and a record player waiting in the wings. ( and maybe another TV, but not That old.)
There will be more questions, of that I am sure. My sincere thanks to you all for the help and encouragement so far.
PJL. From one learner, who knows very little, the only thing I can say,( if thats OK,) is to have a go. With the help available here, it's great and very addictive.
Cheers.
Geoff.

30th Jan 2008, 10:40 pm	#41
Geoff 555 Heptode Join Date: Jan 2008 Location: Bristol, UK. Posts: 981	Re: Introduction and questions re TV22 John thank you for your reply and the invitation, if I am around West Sussex then I will take you up on your generous offer. The matter has now been decided !!!!!! I had another lean and tap session and there was a fair old flash and after I had come down from the ceiling found that the heater was most definitely O C. Another tube will be found. And another question , the scan coils are very well stuck to the tube, what is the best way to remove them without damage please. Many thanks John. Geoff.555.

31st Jan 2008, 9:53 am	#42
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Introduction and questions re TV22 Hello Geoff, Its very rare for a Mullard tube heater to go O/C so I guess it was in a poor state by the sound of it. Tubes are around but unfortunately due to the cult status of the set tend to be a bit of a premium. The Mazda CRM93 used in the Ekco TMB272 can be used almost without modification but it seems such a pity to break one of these brilliant receivers for the CRT. In my opinion it is far more interesting than the TV22 but there you go. I think you will find if you run the set for an hour or so before you attempt to remove the CRT the scan coils shoild be fairly easy to remove. You can S/C the tube heater pins to maintain chain continuity. No need to fit a resisitor in its place for the limited time you are going to run the set. Regards, John.

6th Feb 2008, 7:57 pm	#43
Geoff 555 Heptode Join Date: Jan 2008 Location: Bristol, UK. Posts: 981	Re: Introduction and questions re TV22 Thank you again gentlemen, the scan coils came off in the end. To cut a long story short, for the time being, picture can only be obtained with the contrast turned fully up, if the control is turned down, wiper just off the end stop then it kills the picture, raster. The cut off is very sudden and if I am very careful and slow with the control I can see that the line lock is lost. before the screen goes blank. The control is OK and has been cleaned. Top section PZ 30 etc. Bottom section EL80. All recapped. Any ideas what to go for? Cheers. Geoff.

6th Feb 2008, 8:00 pm	#44
beery Heptode Join Date: Jun 2006 Location: Ware, Hertfordshire, UK. Posts: 988	Re: Introduction and questions re TV22 Hi Geoff, disconect one end of the brightness control and measure its value end to end. It should be 50K, but they often go O/C midway causing some very odd symptoms. Cheers Andy

6th Feb 2008, 10:09 pm	#45
Geoff 555 Heptode Join Date: Jan 2008 Location: Bristol, UK. Posts: 981	Re: Introduction and questions re TV22 Hello Beery have measured and it comes out at 51.3K. Tomorrow I will see if there are any more symptoms. Thank you. Cheers. Geoff.

7th Feb 2008, 11:35 pm	#46
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Introduction and questions re TV22 Hi, I have been watching the thread to encourage me to have a go at my first 405, a Pye I have had for ages. All was doom and gloom as the heater was open-circuit - next post you have a picture. Do let us know what happened?

8th Feb 2008, 12:27 pm	#47
beery Heptode Join Date: Jun 2006 Location: Ware, Hertfordshire, UK. Posts: 988	Re: Introduction and questions re TV22 Hi Geoff, hard to say without seeing the result. Could be... 1.A fault in the video amplifier, so check resistance values around here. Wrong bias here can cut off the tube and cause sync crushing. 2.A fault in the line oscillator circuit. If the line timebase is really out of range then the EHT may be way off as well. Cheers Andy

8th Feb 2008, 9:46 pm	#48
Geoff 555 Heptode Join Date: Jan 2008 Location: Bristol, UK. Posts: 981	Re: Introduction and questions re TV22 OK everyone, it's time for an update and explanation. Set 1. As in all the questions up to the last couple. The tube was completely U/S. Upon further investigation, which I didnt want to bore you with, the more I looked the more I found and came to the conclusion that in the past it had been well and truly got at. Choke linked out, capacitors connected to places that they shouldnt have been etc. The state of the LOPTx finally had me looking in a different direction. Melted pitch and exposed windings and green mould, not a pretty sight. Set 2. I had the chance to buy a tube that was good and upon inquiring found that I could have a chassis with it. This turned out to be in a much better condition than the original. So ------- .Questions about the brightness etc. The instability and whistling was down to a EF80 that although testing OK could be made to stop and start playing about simply by giving it a tap. Sorted. The brightness/contrast problem is still there but is not as bad, still investigating that. I have the chance of a tube that will fit with a change of base and be, at least, watchable, this will be fitted to the original chassis and this will be restored over a period of time. This will give me a chance to gather the various parts that will be needed. There are two radio's and a record player waiting in the wings. ( and maybe another TV, but not That old.) There will be more questions, of that I am sure. My sincere thanks to you all for the help and encouragement so far. PJL. From one learner, who knows very little, the only thing I can say,( if thats OK,) is to have a go. With the help available here, it's great and very addictive. Cheers. Geoff.