Fixing a GEC BT 302 Television

[deepspacedaz]

I sais in post 194

[deepspacedaz]

Is it too late to phone you now I missed your PM

[Heatercathodeshort]

PM sent.

[Heatercathodeshort]

Thanks for the call Daz. At least we now know that your tube has some life in it now you have turned the brightness up.

As suggested the caps in the frame oscillator and output stages will need replacement.
Take care to get them in the right order.

Once you get a decent raster, we are over the hill. Let us know how you get on. John.

[deepspacedaz]

Thanks, John mate I really appreciate the help. Ill order some caps

[deepspacedaz]

Are these the caps.

C110
C112
C113
C116
C118
C115
C117

[Cobaltblue]

Hi Darren

Whilst you wait for your parts to arrive you may wish to watch your set (or a very similar model) being built.

https://www.youtube.com/watch?v=uGzu7vpowHY

Cheers

Mike T

[deepspacedaz]

Thank you so much. nice helpful people

[deepspacedaz]

http://www.tech-retro.com/Aurora_Des...Converter.html

[deepspacedaz]

Is this what i need

[Heatercathodeshort]

Due to the outlay maybe delay the purchase of a standards converter until we get a full screen [raster] illumination. They are an incredible unit without which we could not carry out our TV restorations. There is of course the 'Hedgehog' converter that i am informed is a very good unit but I have not tested one yet.

These are the caps marked in red on the P/C board that if faulty will seriously effect the operation of the frame timebase. The data is scanned from the GEC manual.

Being a printed circuit board there is no excuse for fitting them incorrectly.

The values are: C110 0.1uf C112 0.01uf C113 0.1uf C114 0.1uf C116 0.04uf

C115 0.02uf C117 0.005uf C118 0.005uf.

As I mentioned on the phone the 0.04uf is not easily obtained and may be replaced by a 0.047uf without causing any problem.

Modern capacitors are much smaller than the originals and are usually stocked in 630V rating. These are fine but 500v types would also be fine.

What is known as the cathode bias electrolytic, C111 that I have coded yellow on my scan, may need replacement. When faulty it cramps up the bottom of the picture but you have not reached that far yet. It's value is quoted at 200uf but is not at all critical. This electrolytic is polarized so make sure when the time comes to replace it that you get it connected correctly I.E. negative to chassis. A 220uf 63v cap will be suitable.
The other capacitors I have listed can be connected either way as they are not polarized.

Good luck with it and stick to this one and only task at the moment.

Regards, John.

[deepspacedaz]

Thanks again John

[deepspacedaz]

Morning all. on close inspection, I noticed this wire this morning it was black so I touched it and it just broke in half.

[deepspacedaz]

Looks like the output transformer Wires

[dazzlevision]

John (Heatercathodeshort),

Is the green coloured component in the attached image, the line drive coupling capacitor to the line output valve?

If it is, and it’s a Hunts (or similar), maybe it should also be changed?

Deepspacedaz: are you aware of the need to make sure the dc voltage rating of the replacement capacitors you’ll be ordering is the same or greater than the rating marked on the originals? Best to make a note of these before trying to remove them, as the black outer coating tends to crumble away!

[deepspacedaz]

Did you see the picture i sent

[Heatercathodeshort]

Yes DV You are correct.
As Daz has little experience of working with TV circuits and he now has a bright frame collapse I decided to limit the progress to avoid complications.
I have marked that for future reference once we get a raster. I have spoken to Daz on the phone and he appears to be keen but just lacks the knowledge. It's become a challenge really and hopefully a learning curve [for both of us] Regards, John.

[Heatercathodeshort]

That wire leads to the FOPTX and yes it will give you a complete frame collapse but it must have been intact when you measured the voltage earlier. just clean it up and solder it back together. J.

[deepspacedaz]

Wonder how it burnt out.

[deepspacedaz]

This comp is out of the record player but one of the side pins is missing. can I fix it by soldering another pin one side ? or is the new black comp ok to use instead? Thought I d look at record player while waiting on tv parts.