Bush T57 wobblies - UK Vintage Radio Repair and Restoration Discussion Forum

Colourstar · 25th Feb 2008, 9:03 pm

Finally- after 2 years(!)- got around to looking at the Bush T57 I acquired from a house clearance in Leicester. It's not often you are lucky enough to get a set from the original owner. I believe it had been unused in a back bedroom for years. It's one of my favourite 50s sets- I like the cute console-without-doors look.

Anyway, replacing most of the caps on the tmebase chassis has resulted in image you can see below. I've not even had to touch the height or picture linearity.

Although I've not changed a single component on the receiver deck, it's still managing to produce vision and sound very well. As to the pulling visible in the picture, would I be right in suspecting components around V9 (ECC82), the grandly titled line timebase multivibrator oscillator, or would the sync separator V8 (ECC83) be more likely? I imagine all the caps will want eventually need changing on this chassis, but as I'm running a bit low on spares, I'd like to make the best use of what I have left and attempt a more educated approach!

Thanks
Steve

Steve_P · 25th Feb 2008, 9:12 pm

Go for the parts around V9. How critical is the line hold?

Oh - try an Aerial Connection rather than a lead on the converter. And try switching the Aurora to 'original signal' spec, so it no longer provides equalising pulses.

Cheers,

Steve P.

Heatercathodeshort · 25th Feb 2008, 10:04 pm

If you have not replaced this capacitor, before you get too deep into the circuit,try replacing C39 .1uf. Its the sync coupling capacitor and will cause 'cogging' if at all leaky.
Regards, John.

murphyv310 · 26th Feb 2008, 3:22 pm

Quote:

Originally Posted by Heatercathodeshort

If you have not replaced this capacitor, before you get too deep into the circuit,try replacing C39 .1uf. Its the sync coupling capacitor and will cause 'cogging' if at all leaky.
Regards, John.

Yes the fault is a classic sync problem.
I would agree with John as DC will be on the grid of the sync separator; even a very slight leak will cause the fault.
Trevor

Colourstar · 26th Feb 2008, 10:48 pm

The guilty cap turned out to be C43 which is a 0.1uf. The circuit notes state 'negative going output from V7a is also passed via R44, C43 to sync separator valve' which I'm sure confirms what you were telling me earlier!

I had only one 0.1 cap left in my spares box too. Lucky! Anyway the set is now producing a lovely picture and I'm over the moon with it.

Thanks very much to everyone for their help.

Tazman1966 · 26th Feb 2008, 10:57 pm

Hello Steve.

That's a lovely result. I bet you're pleased as punch as logic has prevailed too

. I hope it has pride of place somewhere.

All the very best,

Heatercathodeshort · 27th Feb 2008, 2:17 pm

Just as a general note on the TV53/63 series and in fact anything you are working on. Trevor did exactly the correct thing here, replacing the very minimum of components so as to get 'something' on the screen.' If you do this the receiver itself will act as its own diagnostic equipment and will spew up its faults for all to see.
I know I go on about this often but I repeat again, replace only one, component at a time powering the set after each replacement. In this way you can see the effect of each renewal and observe the symptoms. There is nothing worse than blanket replacing everything in sight, then ending up with more faults than you started with, often with a puff of smoke! It can take hours of sorting out with much frustration and loss of enthusiasm. All the best detailed notes often fail believe me!
Trevor's Bush is so typical exposing its problems as the work progressed to a satisfactory conclusion. All the best and if nothing else its a good lesson in patience...John.

25th Feb 2008, 9:03 pm	#1
Colourstar Octode Join Date: Feb 2006 Location: Ilkeston, Derbyshire, UK. Posts: 1,398	Bush T57 wobblies Finally- after 2 years(!)- got around to looking at the Bush T57 I acquired from a house clearance in Leicester. It's not often you are lucky enough to get a set from the original owner. I believe it had been unused in a back bedroom for years. It's one of my favourite 50s sets- I like the cute console-without-doors look. Anyway, replacing most of the caps on the tmebase chassis has resulted in image you can see below. I've not even had to touch the height or picture linearity. Although I've not changed a single component on the receiver deck, it's still managing to produce vision and sound very well. As to the pulling visible in the picture, would I be right in suspecting components around V9 (ECC82), the grandly titled line timebase multivibrator oscillator, or would the sync separator V8 (ECC83) be more likely? I imagine all the caps will want eventually need changing on this chassis, but as I'm running a bit low on spares, I'd like to make the best use of what I have left and attempt a more educated approach! Thanks Steve Attached Thumbnails

25th Feb 2008, 9:12 pm	#2
Steve_P Dekatron Join Date: Sep 2003 Location: Bolton, Greater Manchester, UK. Posts: 6,644	Re: Bush T57 wobblies Go for the parts around V9. How critical is the line hold? Oh - try an Aerial Connection rather than a lead on the converter. And try switching the Aurora to 'original signal' spec, so it no longer provides equalising pulses. 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...?

25th Feb 2008, 10:04 pm	#3
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Bush T57 wobblies If you have not replaced this capacitor, before you get too deep into the circuit,try replacing C39 .1uf. Its the sync coupling capacitor and will cause 'cogging' if at all leaky. Regards, John.

26th Feb 2008, 10:48 pm	#5
Colourstar Octode Join Date: Feb 2006 Location: Ilkeston, Derbyshire, UK. Posts: 1,398	Re: Bush T57 wobblies The guilty cap turned out to be C43 which is a 0.1uf. The circuit notes state 'negative going output from V7a is also passed via R44, C43 to sync separator valve' which I'm sure confirms what you were telling me earlier! I had only one 0.1 cap left in my spares box too. Lucky! Anyway the set is now producing a lovely picture and I'm over the moon with it. Thanks very much to everyone for their help. Attached Thumbnails Last edited by Mike Phelan; 4th Mar 2009 at 12:02 pm. Reason: Removed reference to deleted post.

26th Feb 2008, 10:57 pm	#6
Tazman1966 Nonode Join Date: May 2006 Location: St Albans, Herts, UK. Posts: 2,193	Re: Bush T57 wobblies Hello Steve. That's a lovely result. I bet you're pleased as punch as logic has prevailed too. I hope it has pride of place somewhere. All the very best, __________________ All the very best, Tas

27th Feb 2008, 2:17 pm	#7
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Bush T57 wobblies Just as a general note on the TV53/63 series and in fact anything you are working on. Trevor did exactly the correct thing here, replacing the very minimum of components so as to get 'something' on the screen.' If you do this the receiver itself will act as its own diagnostic equipment and will spew up its faults for all to see. I know I go on about this often but I repeat again, replace only one, component at a time powering the set after each replacement. In this way you can see the effect of each renewal and observe the symptoms. There is nothing worse than blanket replacing everything in sight, then ending up with more faults than you started with, often with a puff of smoke! It can take hours of sorting out with much frustration and loss of enthusiasm. All the best detailed notes often fail believe me! Trevor's Bush is so typical exposing its problems as the work progressed to a satisfactory conclusion. All the best and if nothing else its a good lesson in patience...John.