Bush TV24 - SOV and dim picture - UK Vintage Radio Repair and Restoration Discussion Forum

Hunts smoothing bomb · 30th Apr 2007, 9:52 am

Hi all,

I managed to pick up a restored TV24 at the NVCF yesterday and I am pleased with it. It works quite well but needs to be viewed in a darkened room. Are these tubes normally this dim or is it likely that the tubes fitted to these sets are so old now that they are starting to get a bit tired?

I have noticed that someone has made a LOPT for it by winding coils round an outer plastic former which sits around more coils wound on what looks to be a piece of 40mm waste pipe! It is then cured in clear resin.
It works though. The problems I have are, No service data or schematic which I would very much like to have. Also I have a bad case of sound on vision. How can I cure this? On sound passages that are not much louder than a whisper the picture gets modulated with the sound, similar to line tearing?

Also I wouldn't mind checking out this home made LOPT against the service sheet voltages, boost, EHT etc.

Any help will be greatly appreciated.

Many thanks.

Steve_P · 30th Apr 2007, 11:53 am

For Sound on Vision, make sure the set is tuned in! Also, try attenuating the input.

Cheers,

Steve P

Hunts smoothing bomb · 30th Apr 2007, 11:55 am

OK,
Does anyone know where I can get the TV24 schematic? The Valve Page doesn't have it.
Also I am now attempting to slide the chassis out to check everything to make sure it all looks sound, only prob is, is that like Jon Evans, I have a phobia with largish round CRTs

As long as I am careful (which I will be extremely) then there shouldn't be a problem should there? After all, this thing is 57 years old!!

Thanks Lee

Duke_Nukem · 30th Apr 2007, 1:24 pm

Service manual is on the TV22 page :-

http://www.thevalvepage.com/tv/bush/tv22/tv22.htm

The 24 is basically a 22 bit with a bigger bomb fitted in it.

Before even thinking about tilting the chassis, ensure that the CRT is properly secured. I think there should be a clamp, though mine didn't have it, so the CRT literally tried to fall out as I removed the chassis (though fortunately the previous owner had warned me about this).

TTFN,
Jon

PS : Thanks to SWB_18 I have the manual for the early version of the 22/24, PM me if you need that one as it is still sat on my computer awaiting the next site update.

Hunts smoothing bomb · 30th Apr 2007, 3:09 pm

Hi John,

I don't know if it's me but I can only see details for the TV22a and TV24a here. They use a PL81 for line output and something else for sound.

Mine is the TV24 with PL38 and PZ30 in the line output stage and PL33 frame output.

Regards
Lee

Heatercathodeshort · 30th Apr 2007, 9:21 pm

The service data you require is for the TV22, TV24 and TUG24. If you are viewing it in a darkened room I think the CRT MW31-16 is low emission. They are available from various sources.

As for the transformer it is probably OK, and if the EY51 is lighting normally, [I presume it still uses one and has not been converted to a solid state affair] is probably providing enough eht.
If you can get your hands on an EHT meter this would confirm this. Don't worry about the transformer windings' resistances. They will probably differ from the manual but this does not point to a fault. The Mullard tubes are quite robust so no need to worry too much here but wear some eye protection if you intend to handle the naked tube.

Just in case.........The pictures on the TV24 should be bright and high contrast; viewable in a daylight lit room. As Steve suggests, the tuning is probably slightly out. Try some minor adjustment to the tuning knob on the back. Set for best sound and picture. Regards John.

Hunts smoothing bomb · 1st May 2007, 7:18 am

Hello all,

I now have a watchable picture in a brightly lit room!
Looking at the diagram for the TV24a a wire comes from the centre of the brightness control and goes to the CRT grid, there is also a .01uf cap connected effectively from the grid to chassis. I think a mistake took place in the restoration,
In my TV24 I found that the wire went from the centre of the brightness control to the CRT grid, a wire from the grid was then connected to a 5.6k resistor, this resistor then was connected to the .01uf cap and the other side of the cap then went to a terminal on a small transformer on the left side of the chassis on a paxolin panel (frame oscillator transformer?)
This clearly seemed incorrect to me so the wiring is now per the TV24a for the brightness control and I have a good clear defined picture which is viewable in a brightly lit room.

This is my first round tube telly and I gotta say I've been bitten!

Thanks all

Lee

Duke_Nukem · 9th May 2007, 8:17 am

The Mk1 TV24 (TV22,TUG24) service data is temporarily here if still required :-

http://www.thevalvepage.com/tv22temp/tv22temp.htm

Thanks to Phil (SWB_18) for supplying the circuit diagram wot some muppet forgot to scan originally

TTFN,
Jon

Hunts smoothing bomb · 9th May 2007, 1:18 pm

Hi Duke,

Thanks for the sevice info

I may have a problem though, The top chassis containing the timebases and sound output is as I have already said, the mk1 with PZ30, PL38 etc
but the bottom IF chassis has EF80's! not an EF91 in sight!
Does this sound like somebody has cobbled together a TV24a lower deck and TV24 upper deck

? or did the later production runs update the IF chassis before the Timbase chassis

Thanks all
Lee

Neil Breward · 9th May 2007, 1:27 pm

Lee - the Series 2 TV22 and TV24 did use an updated IF unit with EF80s replacing the earlier EF91s, so it most likely IS genuine, not a hybrid!

Cheers,
Neil

beery · 9th May 2007, 1:41 pm

Hi Lee,
yeah that's quite normal.
Bush tended to phase in their changes by changing one deck and later the other.
The TV12AM is a case in point. This has a TV22 top deck and a TV12 RF unit!

Anyway the TV22 top deck with the EF80 lower deck is a very common combination.
What you will find is that compared to the orignal TV22 top deck circuit is that some of the components in the video coupling stage (at least one 0.1uF cap + some other bits) have been omitted from the top deck and will be found on a tag board which sticks up vertically from the back of the RF unit.

So far on the TV22/24 I know of three versions.

Version one is from 1950, uses EF91 valves, a knurled tuning knob and a series one lopty (this is the reliable one with the 'T' shaped laminations).

Version two is from about 1951, uses EF91 valves, a slotted tuning knob and a series two lopty (using 'I' shaped laminations).

Version three is a bit later again, uses EF80 valves, a slotted tuning knob and a series two lopty or three lopty (series three lopty definitely used on the TV24, it has a ceramic former for the EHT heater winding).

Are you asleep yet...

Cheers
Andy

30th Apr 2007, 9:52 am	#1
Hunts smoothing bomb Octode Join Date: Oct 2005 Location: Wimborne, Dorset, UK. Posts: 1,407	Bush TV24 - SOV and dim picture Hi all, I managed to pick up a restored TV24 at the NVCF yesterday and I am pleased with it. It works quite well but needs to be viewed in a darkened room. Are these tubes normally this dim or is it likely that the tubes fitted to these sets are so old now that they are starting to get a bit tired? I have noticed that someone has made a LOPT for it by winding coils round an outer plastic former which sits around more coils wound on what looks to be a piece of 40mm waste pipe! It is then cured in clear resin. It works though. The problems I have are, No service data or schematic which I would very much like to have. Also I have a bad case of sound on vision. How can I cure this? On sound passages that are not much louder than a whisper the picture gets modulated with the sound, similar to line tearing? Also I wouldn't mind checking out this home made LOPT against the service sheet voltages, boost, EHT etc. Any help will be greatly appreciated. Many thanks. __________________ Lee Last edited by Mike Phelan; 25th Mar 2008 at 10:35 am. Reason: Typos

30th Apr 2007, 11:53 am	#2
Steve_P Dekatron Join Date: Sep 2003 Location: Bolton, Greater Manchester, UK. Posts: 6,644	Re: Bush TV24 For Sound on Vision, make sure the set is tuned in! Also, try attenuating the input. Cheers, Steve P __________________ If we've always had it, why is the Car Boot open? You're not sneaking another Old TV in are you...?

30th Apr 2007, 11:55 am	#3
Hunts smoothing bomb Octode Join Date: Oct 2005 Location: Wimborne, Dorset, UK. Posts: 1,407	Re: Bush TV24 OK, Does anyone know where I can get the TV24 schematic? The Valve Page doesn't have it. Also I am now attempting to slide the chassis out to check everything to make sure it all looks sound, only prob is, is that like Jon Evans, I have a phobia with largish round CRTs As long as I am careful (which I will be extremely) then there shouldn't be a problem should there? After all, this thing is 57 years old!! Thanks Lee __________________ Lee Last edited by Mike Phelan; 25th Mar 2008 at 10:37 am. Reason: S&P

30th Apr 2007, 1:24 pm	#4
Duke_Nukem Octode Join Date: Jan 2003 Location: Birmingham, West Midlands, UK. Posts: 1,268	Re: Bush TV24 Service manual is on the TV22 page :- http://www.thevalvepage.com/tv/bush/tv22/tv22.htm The 24 is basically a 22 bit with a bigger bomb fitted in it. Before even thinking about tilting the chassis, ensure that the CRT is properly secured. I think there should be a clamp, though mine didn't have it, so the CRT literally tried to fall out as I removed the chassis (though fortunately the previous owner had warned me about this). TTFN, Jon PS : Thanks to SWB_18 I have the manual for the early version of the 22/24, PM me if you need that one as it is still sat on my computer awaiting the next site update.

30th Apr 2007, 3:09 pm	#5
Hunts smoothing bomb Octode Join Date: Oct 2005 Location: Wimborne, Dorset, UK. Posts: 1,407	Re: Bush TV24 Hi John, I don't know if it's me but I can only see details for the TV22a and TV24a here. They use a PL81 for line output and something else for sound. Mine is the TV24 with PL38 and PZ30 in the line output stage and PL33 frame output. Regards Lee __________________ Lee

30th Apr 2007, 9:21 pm	#6
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Bush TV24 The service data you require is for the TV22, TV24 and TUG24. If you are viewing it in a darkened room I think the CRT MW31-16 is low emission. They are available from various sources. As for the transformer it is probably OK, and if the EY51 is lighting normally, [I presume it still uses one and has not been converted to a solid state affair] is probably providing enough eht. If you can get your hands on an EHT meter this would confirm this. Don't worry about the transformer windings' resistances. They will probably differ from the manual but this does not point to a fault. The Mullard tubes are quite robust so no need to worry too much here but wear some eye protection if you intend to handle the naked tube. Just in case.........The pictures on the TV24 should be bright and high contrast; viewable in a daylight lit room. As Steve suggests, the tuning is probably slightly out. Try some minor adjustment to the tuning knob on the back. Set for best sound and picture. Regards John.

1st May 2007, 7:18 am	#7
Hunts smoothing bomb Octode Join Date: Oct 2005 Location: Wimborne, Dorset, UK. Posts: 1,407	Re: Bush TV24 Hello all, I now have a watchable picture in a brightly lit room! Looking at the diagram for the TV24a a wire comes from the centre of the brightness control and goes to the CRT grid, there is also a .01uf cap connected effectively from the grid to chassis. I think a mistake took place in the restoration, In my TV24 I found that the wire went from the centre of the brightness control to the CRT grid, a wire from the grid was then connected to a 5.6k resistor, this resistor then was connected to the .01uf cap and the other side of the cap then went to a terminal on a small transformer on the left side of the chassis on a paxolin panel (frame oscillator transformer?) This clearly seemed incorrect to me so the wiring is now per the TV24a for the brightness control and I have a good clear defined picture which is viewable in a brightly lit room. This is my first round tube telly and I gotta say I've been bitten! Thanks all Lee __________________ Lee

9th May 2007, 8:17 am	#8
Duke_Nukem Octode Join Date: Jan 2003 Location: Birmingham, West Midlands, UK. Posts: 1,268	Re: Bush TV24 The Mk1 TV24 (TV22,TUG24) service data is temporarily here if still required :- http://www.thevalvepage.com/tv22temp/tv22temp.htm Thanks to Phil (SWB_18) for supplying the circuit diagram wot some muppet forgot to scan originally TTFN, Jon

9th May 2007, 1:18 pm	#9
Hunts smoothing bomb Octode Join Date: Oct 2005 Location: Wimborne, Dorset, UK. Posts: 1,407	Re: Bush TV24 Hi Duke, Thanks for the sevice info I may have a problem though, The top chassis containing the timebases and sound output is as I have already said, the mk1 with PZ30, PL38 etc but the bottom IF chassis has EF80's! not an EF91 in sight! Does this sound like somebody has cobbled together a TV24a lower deck and TV24 upper deck? or did the later production runs update the IF chassis before the Timbase chassis Thanks all Lee __________________ Lee

9th May 2007, 1:27 pm	#10
Neil Breward Retired Dormant Member Join Date: Aug 2005 Location: Keyworth nr. Nottingham, UK Posts: 140	Re: Bush TV24 Lee - the Series 2 TV22 and TV24 did use an updated IF unit with EF80s replacing the earlier EF91s, so it most likely IS genuine, not a hybrid! Cheers, Neil

9th May 2007, 1:41 pm	#11
beery Heptode Join Date: Jun 2006 Location: Ware, Hertfordshire, UK. Posts: 988	Re: Bush TV24 Hi Lee, yeah that's quite normal. Bush tended to phase in their changes by changing one deck and later the other. The TV12AM is a case in point. This has a TV22 top deck and a TV12 RF unit! Anyway the TV22 top deck with the EF80 lower deck is a very common combination. What you will find is that compared to the orignal TV22 top deck circuit is that some of the components in the video coupling stage (at least one 0.1uF cap + some other bits) have been omitted from the top deck and will be found on a tag board which sticks up vertically from the back of the RF unit. So far on the TV22/24 I know of three versions. Version one is from 1950, uses EF91 valves, a knurled tuning knob and a series one lopty (this is the reliable one with the 'T' shaped laminations). Version two is from about 1951, uses EF91 valves, a slotted tuning knob and a series two lopty (using 'I' shaped laminations). Version three is a bit later again, uses EF80 valves, a slotted tuning knob and a series two lopty or three lopty (series three lopty definitely used on the TV24, it has a ceramic former for the EHT heater winding). Are you asleep yet... Cheers Andy