1977 Aphelion TV :Telefunken 712 Chassis

[Jayceebee]

Do you have continuity between the land at both sides of the cut? It looks to me as though both sides should be connected to chassis.

[crustytv]

Yes its BS331

[PYE625]

Oh how I wish I had a stock of TFK boards

The green and blue are ok. I would try to see if the red circuitry is the same as either of those, if not, try making it so.

A sure way to prove a component is ok is to directly swap it with one from the green or blue stage, perhaps starting with the output transistor. Rather rudimentary, but it removes any shadow of doubt of the component being defective under operating conditions.

[Cathovisor]

That break would certainly leave R342, R348, C336 and C351 up in the air...

[Cathovisor]

Yes its BS331

Brilliant. Right board for the set, then.

I'm becoming more and more convinced that that break in the track needs to be bridged.

[crustytv]

Its times like this that I'm really glad I invested in a bench microscope, I spent the last half hour or so carefully removing crud and cleaning the tracks. At least under the scope you can keep any eye on things so as not to cause further damage.

Do you have continuity between the land at both sides of the cut? It looks to me as though both sides should be connected to chassis.

Looking at the picture the right side of the break has continuity to chassis, the left does not.

The last picture shows how Green (T332) tracks appear. Looking at Red T331 now, I would say this was a deliberate track cut, quite why I've no idea.

Red T331, cleaned now track breach is very evident. Was it a deliberate cut and if so why?

Green T332, same track layout but no breach

[Jayceebee]

Then the components on the left as Catho says are floating and C351 is connected to the feedback. Link those two lands and I'm sure we will see some red.

[crustytv]

This morning I decided rather than bodging with jumper wires or employing other unsightly methods of repair, I would spend some time prepping and doing the job properly.

First the tracks around T331 were taken back to copper, the area was then de-gunked with PCB cleaning fluid. Finally finishing with IPA it was ready for the next stage.

Out with the PCB track repair kit, using a sharp craft knife I formed the tracks that would repair the breach and provide the missing T331 Base track/pad. This is really tricky and finicky work, eventually I got them in place. The tracks were then tinned and tested for continuity, all was well. T331 was then re-installed and finally the resist applied.

I know its not pretty but in my opinion far better than how I found it and it looks better then jumper wires. I've left the bread board piggy backed in with the IC transposed wires, I guess we're hoping for T331-base to now have a good waveform if this was indeed the problem.

Fingers crossed, are we having bets?

Cleaned and prepped

New tracks installed

T331 now installed and resist applied

[Cathovisor]

Digital extremities crossed here...

[crustytv]

We now have Red drive

Next I'm going to remove the hardwires for the bread board piggy jobby then reinstall the IC socket chip. Hopefully Carols Red top will be present as well as bubbles green body. Still begs the question why was the track cut and it was cut the edges were perfectly straight and the board was gouged.

[Niall]

I love this stuff! We should sell it to Discovery channel as a programme idea as it has all the tension they try so hard to create.

"A fault has been identified and a repair done - join us after the break as we apply power and see if it's fixed!"

[Cathovisor]

We now have Red drive

YESSS!!!!

Still begs the question why was the track cut

<mode=pedant>
Still raises the the question
</mode=pedant>

[PYE625]

Very odd why the track had been cut.....possibly damaged by very careless persons previously, or cut due to tracking from the one above.
But in that case, you would expect the cut to be by-passed surely.

[crustytv]

Houston.....Telefunken bay here, the Red has landed.

Now needs a re-setup

[PYE625]

Lovely !!!!! Well done

[Cathovisor]

Hopefully now all the voltages will settle to where they should nominally be.

[sideband]

That looks pretty darn good! Not much needed there and what a cracking picture! You would have done very well for yourself back in the '70's fixing these things.


Well done!

[Katie Bush]

I love this stuff! We should sell it to Discovery channel as a programme idea as it has all the tension they try so hard to create.

"A fault has been identified and a repair done - join us after the break as we apply power and see if it's fixed!"

Well, it would be more realistic than 99% of the crap they currently churn out... Whereas "Greg" is a fictitious name I have inserted, Discovery Channel runs on one basic premise - "Greg and the boys are doing well, BUT, there's a problem" - without which there wouldn't be "show" to show!

[Katie Bush]

Very odd why the track had been cut.....possibly damaged by very careless persons previously, or cut due to tracking from the one above.
But in that case, you would expect the cut to be by-passed surely.

From quite a few posts back, I've had a kind of feeling that this set might well have been a work in progress that someone has abandoned - either got out of there own depth, got fed up with it, or dare I even say, passed on before completing their work.. Though I did wonder at one point if this set might have ended up as workshop donor - hence my query a long way back about the correct chroma panel for the set.

[PYE625]

Well, it shows how much notice I take......I've only just seen that the tube is not a Delta type

[Red_to_Black]

Brilliant
Cracking picture too.

[Jayceebee]

Excellent result.

[marc]

Well impressed !
Nice one Chris

Marc.

[The_Teleman]

Well done Chris !

Man made faults are always the most difficult to find
Another cracking set saved
I would like to see the picture when it's set up I'll bet it's a cracker

Chris

[crustytv]

Would someone with Radio Museum access consider asking the question what model this TV is, I would love to know. They can be pointed at the main site page if necessary http://www.radios-tv.co.uk/1977-telefunken-palcolor/ I expect there might be a fair German contingent over there that might know.

Then again maybe not, perhaps it was just a UK market set. There appears to be absolutely nothing on the web ( that I can find ) other than the pages I have posted on the main site and here. I find that incredulous even the Keracolor and the Aphelion ( which looks to have copied the Telefunken cabinet exactly. Did they purchase the rights to the cab design from TFK? ) both niche sets and both have info out there about them.