Hi Fred and Ian
Ok, have done an ohms reading on the vertical output transformer:
Primary side has 2 tags and a centre black
Reading green and blue wire to red wire = 0.400Kohm
Secondary side has 3 tags yellow and grey with orange centre tap
Reading: yellow to grey = 350.3ohm.
Yellow to orange = 151.6 ohm
Grey to orange = 0,509Kohm
Reading taken with the vertical yoke plug disconnected.
I took a picture of the transformer that I can email to you.
Hopefully this gives some useful information.
Cheers
Scott

Hi Scott.
That is confusing.
The cct original tranny had:
A plate driven primary 2 ends red, blue.
The secondary drives the yoke, 2 ends black, green.
The feedback winding has 3 ends, brown,yellow(tap),orange.

Also:
When you write 0.4Kohm do you mean 400 ohm?
Then we have 350.3 ohm and 0.509Kohm, do you mean 509 ohm?
Stick to the same mulitplyers on a readings so as not to confuse me.

Ok, readings in the hundreds of ohms sound in the ball park , at least there is no open circuit or short circuit.

"Primary has two tags and a centre black."
Do you mean it has 3 ends coming out of it?
"Secondary side has 3 tags"
But the secondary should only have 2 ends to drive the yoke.
Then what of the feedback winding?
(yellow, grey, orange) (And no its not a CENTRE tap, its offset)

Oh the "secondary" you mention sounds like the feedback winding, I hope that is not trying to drive the yoke!

OK, I think you are getting closer here.
If the feedback winding brown,yellow,orange, has been connected colour by colour (by the tech) the actual windings for the critical feedback signal may not be correct!
Old tranny was brown,yellow(tap),orange.
You have orange,yellow(tap),grey.
If the winding is swapped end for end the phasing and the amplitude of the feedback signal would be incorrect and muck the linearity up no end.
If it was easy to do I would swap your orange and grey and see what happens!

I think we are getting near to the cause.

Yes would like to see pix of tranny, I love a mystery.
My email should be open.

Fred.

Hi Scott, outlooked had junked your email on me!
Your send was ok.
Swap the orange and grey.
Fred.

Fred is on the right track as usual. Agree.

Thanks gents.
I’ll swap the wires and report back
Cheers
Scott

Update gents,
Swapped the orange and grey wires, it didn’t like that.
Made it worse and a lot of odd sounds from the audio so have put it back.
Could it be yellow and orange should be swapped l?
Cheers
Scott

Hi Scott, damm!
Worse is not good and odd sounds from the audio sound like cross coupling on the HT rails between the Vertical stage and the auido stage possibly due to bad filters!

BUT,
Lets try and verify where the ends go.

By your measurements on the feedback winding the orange is one end, the grey is the other and the yellow is the tapping.
The yellow tapping is closer by ohms to the orange end.

So, your orange should connect to the plate circuit of the triode, the tapping yellow should hook to the junction of cap 217 and cap 219 and the grey goes to the top of the 50k lin pot.
This needs to be verified.

The colours on my circuit for model T236 (730 SU11) were orange yellow and brown. Your tranny has the colours the same except you have a grey wire instead of brown.
That needs to be verified.

I would expect your green,blue wire to go to the 6BM8 plate and the other end red to go to the HT rail.
That needs to be verified.

That should make the stage work and then the low ohm winding drives the yoke coils thats the winding that was black, green on the original. That needs to be verified.

This is a real grind, four items to verify, but before we condemn the transformer type we have to ensure it is connected as per the circuit.

Fred.

Thanks Fred.
If the yellow is the tap, shouldn’t it be on the centre tag? Currently it’s on one end as per the pic.
I will verify where the other end of each wire goes and let you know.
I really appreciate your assistance.
We will get it working
Cheers
Scott

Scott , thats the hard thing to tell cos we dont know how the tranny was wound.
A tapping SHOULD be between the ends by the HEIGHT of the winding BUT the winder could have put the tap at one side of the bobbin or at the center to follow some custom.
Your ohms check suggests yellow is a tap, I'll go with that.
Fred.

Hi Ian and Fred
I have traced the connections from the transformer and they are connected as per the schematic. (Grey was originally brown)
I just took a close look at the installed vertical output transformer,
it’s a “Radar TV Replacements Cat no. 14”
This may provide some identification for it.
Cheers
Scott

Found in a 1966 Radio Parts Catalogue:

Radar part No. 14 replaces STC part No. C54349

C54349 was used in STC T214, T215, T217 & T237 series TV's.

That’s very helpful thanks
Well according to the schematic the part number for the T236 is SP54349E.
In theory it should work fine???
The plot thickens…
Cheers
Scott

Hi Scott, there is something wrong in there!
A short run with the wires in the wrong order should not have hurt anything.
(just a thought about "new " valves. I have used a lot of "new" old stock valves and have had a definite failure rate. Nothing works better than an old but good "miniwatt or philips" original valve as made back then for TV use. Aussie 6BM8's are as common as mouse droppings and always in the junk box. I would swap to a good oldy 6BM8 just to be sure and avoid like poison any new "Chinese" valves. I struck a bag full of Chinese 12AU7's that looked right, had the right pin connections, but were hopeless as twin triodes when actually pushed hard. They simply could not pass current when used in the original purpose TV use!)

This is all sounding like the tranny has a fault and its getting worse.
The most likely thing wrong would be a shorted turn fault which can come and go and certainly give you all the faults you see, loss of linear sweep and disturbance of the waveshape.
I have a horrible feeling your original diagnosis was correct, the transformer is at fault.
At least you have gone through all the external components.

The stage needs to be scoped to check the actual waveshapes to see if they are correct and if not why not.
Time for the CRO and the extender leads to work on a hot chassis.
Its getting not so easy now!

The key to a tranny being suitable will be if it has the three windings.
My field service manual shows only the model 730 SU 8 , 9 and 10 used the the three winding tranny .
The others have different circuits with auto and two winding trannys.
Fred.

I don't think it is the right vertical output transformer. The correct one for your TV is E54349 (you'll see it clearly on page 2 of the service manual).

There are only two STC replacement vertical output transformers in the Radar list: 14 for C54349 & 15 for D54349 (used in the later STC T500 Series)

Thanks monochrome
That creates a dilemma
Cheers