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Old 3rd Jun 2006, 10:25 am   #21
Courtney Louise
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Default Re: Can somebody please repair My TV22

Hi Jim, I think the frame collapse is one line, the tube setup is all over the place and I havent even tried to focus it yet.
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Old 3rd Jun 2006, 10:27 am   #22
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Default Re: Can somebody please repair My TV22

The frame panel on the right hand side had been completely cooked, so I took the one I had out of a scrap TV22, and metered every resistor and replaced all the caps on that.
The 2 main green resistors are spot -n and well within tolerance and not showing the slightest wear. The rest being 10% ones are all quite close although a couple are marginally high.

But with the transformer disconnected I can't get a reading from one side of it, but the correct reading from the other.

Andi
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Old 3rd Jun 2006, 10:39 am   #23
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Default Re: Can somebody please repair My TV22

That doesn't look promising

Is there a spare transformer in the scrap set? Make sure that all the other components are OK before you fit it though, we don't want a repeat performance!

Jim.
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Old 3rd Jun 2006, 11:02 am   #24
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Default Re: Can somebody please repair My TV22

Another update, sorry for this Paul...

I have now found a mustard C57 and I still only have a nice flat line, nothing like before...

Nice and sharp (focussed it a bit too)

Heres a pic of what I now have

Andi

Jim, the one in the scrap set reads the same with a good secondary but a shot primary...
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Old 3rd Jun 2006, 11:25 am   #25
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Default Re: Can somebody please repair My TV22

Hi Andi,

that's what I would expect for frame collapse

I think you need to start looking for a new transformer, or re-winding the one you have.

Don't run the set like that for long, or you will get a burnt screen - turn the brilliance right down while you're making further tests.

In the meantime, you can sort out the RF strip

Jim.
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Old 3rd Jun 2006, 11:43 am   #26
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Default Re: Can somebody please repair My TV22

Just started on the RF board, I dont have many of the low value caps, so need to get an order into Farnell soon...

MODERATORS : Please dont delete this thread as I am going to use it to write up a complete repair guide (hopefully) and if anyone else has any symptom/repair info from their sets please let me know and I will add them to the site too.

Andi
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Old 3rd Jun 2006, 11:53 am   #27
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Default Re: Can somebody please repair My TV22

Hi Andi
Quote:
Originally Posted by Jarl Ayari
I know this thread is goign to be a bit long but maybe this could turn into a restoration guide for a TV22 as I havent been able to find one and these are extremely popular sets.
Definitely one for the archives in time; I've never been inside one and this thread's not put me off getting one eventually. I look forward to further progress reports, good luck

Regards, Kat
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Old 3rd Jun 2006, 11:57 am   #28
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Default Re: Can somebody please repair My TV22

Thanks Kat Seeing these old sets in action at the NVCF kinda gave me the bug and incentive to get one and get one running. So you in part are an inspiration to this...

Andi
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Old 4th Jun 2006, 5:43 pm   #29
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Default Re: Can somebody please repair My TV22

Hi again,

A new update.

After getting My AVO 8 back I have re-metered the frame transformer and it's metering ok with the Avo. Even though it wouldnt read at all with the DMM; very odd...

So my next question as I don't quite understand voltages: where can I check for the sawtooth and what voltage is it likely to be at? I am guessing at the grid of V15b?

Andi
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Old 4th Jun 2006, 5:56 pm   #30
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Default Re: Can somebody please repair My TV22

Quote:
Originally Posted by Jarl Ayari
have re metered the frame transformer and its metering ok with the Avo. Even tho it wouldnt read at all with the DMM very odd...
For unknown reasons, my new and expensive Fluke DMM really struggles when measuring the resistance of some inductive components like transformers, with the reading hunting and even going negative

I always use my 1-at-a-boot-sale 1950s ex-GPO meter for this, spot-on measurements in seconds.

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Old 4th Jun 2006, 6:32 pm   #31
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Default Re: Can somebody please repair My TV22

Should the metal rectifier read as a normal diode? I get about 1.2Meg one way and 1.7Meg the other...

About 115v on the green side and about 160v on the red

Is there anything else that can cause frame colapse?

Andi
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Old 4th Jun 2006, 9:32 pm   #32
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Default Re: Can somebody please repair My TV22

Quote:
Originally Posted by Jarl Ayari
Should the metal rectifier read as a normal diode? I get about 1.2Meg one way and 1.7Meg the other...
In a nutshell....No! A metal rectifier is a very non-linear device and at low voltages, the forward resistance will be almost as high as reverse. As you increase the forward voltage, the resistance falls. So you can see that if you measure with an Avo ( or almost any other meter) where the terminal voltage is only 1.5 volts or so, the forward resistance will measure very high. Best thing to do would be to replace it with a silicon type and a series resistor. Start with around 200 ohms at 10 watts and then experiment with the value until you have correct HT. You can leave the original in place but disconnected so to maintain appearance.


Rich.
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Old 4th Jun 2006, 10:19 pm   #33
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Default Re: Can somebody please repair My TV22

Internal appearance is not what I am doing at the moment, I just want it to work. I doubt I could ever make it look original inside as some of the caps I have used are as big as the waxies I have taken out and a few parallel caps too, in places to get the values.

Once it is working and stable I might then tidy the tagstrips back up, but right now its bottom of my list.

I didn't know that about metal rectifiers, so that's very very interesting.

Thanks Richard

Andi
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Old 5th Jun 2006, 10:49 pm   #34
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Default Re: Can somebody please repair My TV22

Hi,

Can someone please tell me where to scope for the sawtooth. I have changed every capacitor in the whole section and nearly every resistor and also T4. Apart form changing T5 and the scan coils I am at a loss...

Thanks

Andi
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Old 6th Jun 2006, 2:14 pm   #35
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Default Re: Can somebody please repair My TV22

Quote:
Originally Posted by Jarl Ayari
Hi,

Can someone please tell me where to scope for the sawtooth. I have changed every capacitor in the whole section and nearly every resistor and also T4. Apart form changing T5 and the scan coils I am at a loss...

Thanks

Andi
Pin 1 and 2 of V2 (Triode ECL80). Disconnect Pin8 g2 of the ECL80 to make
sure that the pentode is not overloaded during your experiments.

Darius
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Old 6th Jun 2006, 2:20 pm   #36
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Default Re: Can somebody please repair My TV22

Hi Darius,

Thanks for that I want to see if the sawtooth is actually being generated and then see whats happening. I cant see anything that could be wrong...

Andi
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Old 7th Jun 2006, 3:18 pm   #37
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Default Re: Can somebody please repair My TV22

Hi Guys...

Latest update...

All component numbers I quote are from Trader sheet 1003/T15

T4 has been changed as has C51, MR1, C52, R52, C53, R53, C55, V15, C56, C57, and the scan coils on the tube itself and I am still getting no frame drive...

Any more clues?

Andi
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Old 7th Jun 2006, 8:57 pm   #38
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Default Re: Can somebody please repair My TV22

Hi Andi, any joy with the scope pictures yet?

BEWARE that you will need to run the set through an isolating transformer as it is an AC/AC type before you attach the scope (there are other tricks but if you don't know what they are it's best not to!

You can also try injecting 6.3V 50 Hz from an old heater transformer into the op valve grid to see if that stage works (the art of coarse servicing!).

HTH Ed
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Old 7th Jun 2006, 9:40 pm   #39
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Default Re: Can somebody please repair My TV22

Hi Ed, right now I will try anything as my head hurts and I am lost and in well beyond my depth.
I am no TV repair person and even though I haven't blanket changed everything, I did the waxies, then looked at the circuit at what I thought could cause it and now have everything changed, bar T5 and I have one, but its a pain with all of the short tight wires to get a new one in.

I will try the heater tranny option as I don't have an isolating one and I don't think my scope goes above 100v input anyways... :-(

Andi
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Old 8th Jun 2006, 11:24 am   #40
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Default Re: Can somebody please repair My TV22

Hi Andi. The scope input voltage range is not the problem. It is the fact that the scope is earthed and you then connect the probe common to and ac/dc chassis. The probe common is connected to earth via the scope mains lead, hence possible large current thro scope (not good) from the chassis of the TV.

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