A tale of two Bush TV22 LOPT - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

1100 man · 27th Apr 2020, 10:50 pm

Hi Dave,
I think that deserves top marks as a work around! I also would not have thought of doing that!!

I'm surprised that the frame linearity is so good.

All the best
Nick

Davewantsone · 28th Apr 2020, 9:38 am

Well it will do as a work around. I have made the connections tidy and fastened the two transformers to the main frame.
I had a bad case of mains hum from the loudspeaker in this set. I would like to thank L.Lawry-Johns (RIP) for solving the problem. In his Practical Tv article "Servicing TV Receivers" number 3 (1950s), he told me what the problem was. A earthing nut and bolt just below the fuse holders comes loose. This was in my case tightening up result no more hum!

Davewantsone · 28th Apr 2020, 4:09 pm

Well the set is now like Jack "back in the box". The fold over on the LHS with a white line if I tried to increase the width was caused by the 1k ohm resistor going to the grid of the line output valve. I had checked it earlier and it read 1.1 k ohm. This was a 10% tolerance resistor so I did not change it . I tacked a 13k ohm across it and it took the resistance down to 1.04 k ohms. On switch on no foldover and plenty of width from the control that actually worked correctly and no white line! I measured the EHT and it had gone up to 7.25kV!
Thanks again for the help.

Lloyd 1985 · 28th Apr 2020, 4:20 pm

Might have to check that resistor on mine, it’s got similar ringing/ fold over problems, and generally looks a bit naff... has been a good few years since restoration now though!

Regards
Lloyd

27th Apr 2020, 10:50 pm	#21
1100 man Octode Join Date: Apr 2016 Location: Ventnor, Isle of Wight, & Great Dunmow, Essex, UK. Posts: 1,377	Re: A tale of two Bush TV22 LOPT Hi Dave, I think that deserves top marks as a work around! I also would not have thought of doing that!! I'm surprised that the frame linearity is so good. All the best Nick

28th Apr 2020, 9:38 am	#22
Davewantsone Hexode Join Date: Dec 2011 Location: Wigan, Greater Manchester, UK. Posts: 291	Re: A tale of two Bush TV22 LOPT Well it will do as a work around. I have made the connections tidy and fastened the two transformers to the main frame. I had a bad case of mains hum from the loudspeaker in this set. I would like to thank L.Lawry-Johns (RIP) for solving the problem. In his Practical Tv article "Servicing TV Receivers" number 3 (1950s), he told me what the problem was. A earthing nut and bolt just below the fuse holders comes loose. This was in my case tightening up result no more hum!

28th Apr 2020, 4:09 pm	#23
Davewantsone Hexode Join Date: Dec 2011 Location: Wigan, Greater Manchester, UK. Posts: 291	Re: A tale of two Bush TV22 LOPT Well the set is now like Jack "back in the box". The fold over on the LHS with a white line if I tried to increase the width was caused by the 1k ohm resistor going to the grid of the line output valve. I had checked it earlier and it read 1.1 k ohm. This was a 10% tolerance resistor so I did not change it . I tacked a 13k ohm across it and it took the resistance down to 1.04 k ohms. On switch on no foldover and plenty of width from the control that actually worked correctly and no white line! I measured the EHT and it had gone up to 7.25kV! Thanks again for the help. Attached Thumbnails

28th Apr 2020, 4:20 pm	#24
Lloyd 1985 Nonode Join Date: Jun 2008 Location: Coningsby, Lincolnshire, UK. Posts: 2,820	Re: A tale of two Bush TV22 LOPT Might have to check that resistor on mine, it’s got similar ringing/ fold over problems, and generally looks a bit naff... has been a good few years since restoration now though! Regards Lloyd