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CVC5 first light

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Mikey66
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Here's a couple of pictures of the ITT KB CVC5 I bought.

And here's the focus modification

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Topic starter Posted : 23/10/2013 7:43 pm
neil1974
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Hi Mike, That doesn't look too bad for first switch on :aad . and if it's any consolation my CVC8 came on after I replaced the mains switch and worked ok ish first time until I tried the set a few days later when I had a dead short across the mains input (switch is fine). and my CVC5 is pretty much dead too :bbd .

Cheers,Neil.

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Posted : 23/10/2013 8:18 pm
Mikey66
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I would try the mains filter cap on the CVC8 Neil. It's situated on the control panel near the manins switch.
My CVC7 had a faulty switch too.

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Topic starter Posted : 23/10/2013 8:38 pm
Anonymous
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See what you mean about the focus lead is the resistor connected straight to the tube pin?
rob t

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Posted : 24/10/2013 12:02 am
Mikey66
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Yes Rob

The pin has been bent outwards and the resistor soldered onto it. I reckon I can bend the pin back OK but I need to source another CRT base socket

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Topic starter Posted : 24/10/2013 12:10 am
sideband
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I reckon I can bend the pin back OK

:ccf ! As long as it doesn't snap off flush with the glass....I had that happen to me once but it was in the days when CRT's were easily available!

Rich

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Posted : 24/10/2013 12:23 am
neil1974
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Would warming the pin with a soldering iron first help :aab .

Cheers,Neil.

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Posted : 24/10/2013 3:28 pm
Refugee
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I would have a look at the socket crimps used in hard drive plugs. These can be bought in bags of 100 and the next size down from the actual hard drive one could be used with the pin as it is on a fly lead.
They are always worth a punt when you are making adapters of any kind.

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Posted : 24/10/2013 4:16 pm
Mikey66
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Getting the focus wire off was no problem for my metcal iron, I even used braid to get the excess solder off the pin. Then I very, very carefully bent the pin straight.

I wore protective eyewear and the set had been on for 15 minutes to warm the glass up and minimise any thermal shock from my iron.

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Topic starter Posted : 25/10/2013 12:48 am
neil1974
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Must be a relief that it didn't snap Mike :bba .

Cheers,Neil.

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Posted : 25/10/2013 1:42 am
Refugee
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I would have put my money on the tube going to air for that one.
You are very lucky taking a risk like that.

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Posted : 25/10/2013 4:14 am
Mikey66
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That's exactly what I did Trevor. I also used two pairs of pliers when bending the pin straight. A pair to support the base of the pin and a pair to do the bending.

I had CRT base PCB from a scrapper This has been pressed into service

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Topic starter Posted : 25/10/2013 3:17 pm
Refugee
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What was actually wrong with the old CRT base to make the previous engineer carry out that modification?

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Posted : 25/10/2013 3:29 pm
Mikey66
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Here's a picture of the old crt base panel and the cannibalised socket

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Topic starter Posted : 25/10/2013 6:53 pm
Refugee
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It looks more like a socket problem.
Having a spare PCB is certainly a quick solution to the problem.

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Posted : 25/10/2013 7:01 pm
Mikey66
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The pcb and track from pin 9 are all missing as is the focus spark gap. I think there must have been some liquid damage and the engineer just cut away the damaged parts of pcb and crt socket.

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Topic starter Posted : 25/10/2013 7:08 pm
Refugee
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If there is no corrosion else ware it may have been caused by conductive dust of some kind.

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Posted : 25/10/2013 8:05 pm
Mikey66
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There was corrosion on 3 of the pins in the tube base connector. I didn't have a new tube base connector, only the old one from my CVC7 which had several badly corroded sockets - so bad that it was loose.
I have a scrap CVC5 chassis I used as a parts doner its crt base connector was used to repair my CVC7. Fortunatly I retained the old base connector.
This was pressed into service using the good sockets from my CVC5 and a couple of marginal ones from the CVC7. Idealy I would have fitted a new B12-244 connector but these seem to be as rare as hens teeth.
Anyway the set now prodoces a nice bright picture which rolls like buggery for the first minute or so :bba
A new PCL805 will sort that I hope :thumb

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Topic starter Posted : 25/10/2013 8:24 pm
Anonymous
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Great job, but glad you and the CRT survived this reapir :aad

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Posted : 31/10/2013 2:18 pm
Mikey66
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It's getting there now

A new PCL805 cured the rolling picture at switch on, I also replaced the high value resistors in the focus circuit and the large 0.47uF cap.
The only issues I have now are caption buzz and there is also a hum coming from the speaker.
I'm using it as my main set and so far no other faults have shown themselves.

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Topic starter Posted : 31/10/2013 5:29 pm
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