Bush Tv43 faults

[slidertogrid]

Hi
I bought this set a few years ago very cheaply from Harpenden.
I took the set to Sean's radio workshop day having had it in front of a radiator for a couple of weeks.
Some progress was made on the day and I managed to get a rather lop sided blurred raster to appear for a while.
Over the last few days I have slowly worked my way around the set changing leaky wax caps, the set now produces a picture of sorts, I have no sound from the IF deck (the amplifier is working). and a horrid frame fault, the picture is very compressed at the bottom and the height changes and folds up at the bottom on scene changes.
On a still picture the bottom of the picture can be seen steadily rising and falling as if there may be some hum present?
The picture looks a bit grey and flat in the photo it has improved since then with the renewal of some of the EF80 s .
The tube is a regun and nice and bright but most of the valves were clapped, I think maybe the valves have been over run in the past probably when the original tube was failing.
I think most of the valves have now been changed with the exception of the EY51.
The only electrolytic replaced so far is the one on the frame output cathode.
The question as to how much longer it is going to be on the dining room table was asked today, so I really should move it by the weekend....
Any suggestions on how to sort the frame fault would be greatly appreciated !

Rich

[Heatercathodeshort]

For the frame fault try replacing the electrolytic decoupling the screen grid of the frame output valve. It is mounted under a clip on the chassis. I think it is around 8uf 350v. I presume you have replaced all the waxies in the frame osc/output. John.
PS. Don't forget the ones mounted on the back of the frame output transformer tags.

[slidertogrid]

Hi John,
Thanks for the suggestion, Today I have replaced both the 8mfd caps, the one you suggested plus the one on the boost line.
I didn't have any 8mfds so I used 12.5 mfd that I had to hand.
The symtoms are a little better, the frame does not fold up so much on scene changes but the bottom is still very compressed and the frame still "sponges" up and down.
next step I suppose is to sub the main smoothing and res caps?

[Heatercathodeshort]

Hello Rich,
I have just repaired a TV43 and had similar frame faults. Double check your capacitors and connections. It is incredibly easy to make a mistake with the famed Bush tag board construction. Don't forget there are caps behind the frame output transformer tag strip. When corrected the linearity is 100% with masses of height to spare and lin pots set about mid way. Should not be critical in any way. 8-25uf caps are fine by the way. J.

[Tractorfan]

Hi,
I had a Bush43 when a teenager which I painted fluorescent orange, red & silver in those far off psychedelic 70s. It worked reasonably well in a darkened room, but had an appetite for ECL80 frame output valves as they lived in the only ceramic valveholder in the set and used to crack across the base. ECL80s weren't rare then. Just my 2cents worth.
Cheers, Pete

[DangerMan]

When you are sure that all caps have been swapped with no mistakes, I'd be inclined to measure the electrode voltages around the ECL80. This might show a problem.
Don't forget to measure G1 of the pentode too, I've had a TV32 (similar circuit) with a conductive tag board on the frame op transformer that caused DC to appear on this grid. The result was exactly as per your photograph. Any of the tag boards can become leaky if they have been damp enough for a long enough, so the fault can still be elusive.
Pete

[slidertogrid]

Thanks guys for the help and advice
Today I rechecked my work and found I had got the value of one cap wrong (I really must get some better reading glasses!) it should have been a .02 I had fitted a .001 , so quite wrong
After replacing the cap with the correct value I had much better control over the linearity, but it was still a bit folded at the bottom and the foldover slowly rose up and down.
I removed the chassis and rechecked the capacitors and soldering on the frame output transformer.
The tag board on top of the transformer was very greasy and dirty so I gave it a good clean with carb cleaner and cotton buds, then I resoldered all of the tags being very careful not to get them too hot.
Success! I now have good stable frame at last!
The picture on the test card really is not bad at all, not perfect but it will do me!
This evening I tackled the sound fault, I found that by detuning to the point that the picture broke up I could get very low sound, further de tuning resulted in a loud buzz.
I prodded around the IF transformers and every stage seemed to be working and fairly lively so I had a prod around the EB91 sound detector, the anode voltage of the EB91 was only 40 volts and slowly fell to zero.
After another cup of tea I persued the missing volts and after a while I found a wire link in a sleeve that had gone open circuit, the wire had a little pinch in it and fell in half as soon as it was touched.
One link later and sound blasted forth!
The volume control is very noisy, the focus adjustment stuck and the line lin a bit poor on the left of the picture so I think it will be "dinner on a tray" for a while yet.
Many thanks for the advice, it soon put me on the right track
This is only my second telly repair and I am already planning my next one!

Rich.

[slidertogrid]

A couple of pictures of the set thus far.... I really must clear it from the dining room table this weekend !
Rich.

[Sean Williams]

It will look even better once I get the base card for it back to you... Still, it is safe here at the moment.

Good results though, I had a feeling it would be a decent set once you had ironed out the bugs

[audion_1908]

how is the bush tv43 going?

How is the Bush TV43 going?