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-   -   Bush TV12 restoration. (https://www.vintage-radio.net/forum/showthread.php?t=73273)

FERNSEH 22nd Aug 2011 12:05 pm

Bush TV12 restoration.
 
2 Attachment(s)
Let's see if I can get this set working before the weekend.
The results so far are a narrow thin horizontal line and an indicated 4KV EHT.

DFWB.

Andy Doz 22nd Aug 2011 12:08 pm

Re: Bush TV12 restoration.
 
1 Attachment(s)
I'll race you .. I've got a TV22 just arrived. Not powered it up yet , but I'm hoping the LOPTx is OK, so the line whistle will drive away the woodworm in the side panels :)

FERNSEH 22nd Aug 2011 12:52 pm

Re: Bush TV12 restoration.
 
Quote:

Originally Posted by Andy Doz (Post 459432)
I'll race you ......

OK the challenge is on.

David.

Peter.N. 22nd Aug 2011 3:49 pm

Re: Bush TV12 restoration.
 
I would turn the brightness down on that!

Peter

FERNSEH 22nd Aug 2011 3:58 pm

Re: Bush TV12 restoration.
 
Following my policy of Glasnost (openess) I can report that the line timebase has packed in.

DFWB.

Heatercathodeshort 22nd Aug 2011 4:27 pm

Re: Bush TV12 restoration.
 
No excuses allowed! As soon a a challenge rears it's head you creep back into the workshop! I'm backing you David. Don't allow the TV22 brigade to intimidate you. :D.
The EHT on a TV12 is rarely above 4.9kv unless it is fitted with the later line output transformer. It still gives a good picture even with this very low EHT potential. Boost cap and coupling caps come to mind. It was a good first light. Pity the bulb in the lighthouse popped just before you crashed into the rocks.
Even with that minimum display it shows a good CRT and LOPT, the rest is easy.:-) Regards, John.

murphyv310 22nd Aug 2011 4:44 pm

Re: Bush TV12 restoration.
 
Has war broken out in the vintage community?

FERNSEH 22nd Aug 2011 4:58 pm

Re: Bush TV12 restoration.
 
Hi Trevor,
Not exactly war, let's say a difference of opinion. Eine Meinungsverschiedenheit

TV12 versas TV22, no competition. Everyone knows which is the better set.

DFWB.

Andy Doz 23rd Aug 2011 8:04 am

Re: Bush TV12 restoration.
 
... it's just I happened to have a TV22 to do at the same time ...

I can confirm my line stage doesn't work either, the top cap's fallen off my line bottle.. :(

Andy Doz 23rd Aug 2011 8:16 pm

Re: Bush TV12 restoration.
 
1 Attachment(s)
A few caps. Repair the top cap on the line output valve ... and up with the volts!!

... there's all to play for.

audiomagpie 23rd Aug 2011 9:45 pm

Re: Bush TV12 restoration.
 
Nice to see the tube 'smiling'!

You know you're well on your way at that stage!

Greg

FERNSEH 23rd Aug 2011 10:34 pm

Re: Bush TV12 restoration.
 
I've been working on the TV12 today. The line oscillator failure turned out be be a broken tag on the EF50 valveholder. An easy fix. So it's back to the original line TB fault, lack of width. The 'scope shows that the sawtooth drive is correct: 30volts @ 100microseconds. Note the "sit up" on the flyback part of the waveform. The frame timbase needs some attention.
That's the next stage of the restoration.

DFWB

FERNSEH 23rd Aug 2011 10:37 pm

Re: Bush TV12 restoration.
 
2 Attachment(s)
Some pictures. The broken valveholder tag can been seen.

DFWB.

FERNSEH 23rd Aug 2011 10:52 pm

Re: Bush TV12 restoration.
 
1 Attachment(s)
The frame timebase turned out to be the same valveholder problem. Two broken tags. The FTB now works in a fashion but the hold control has a dead spot at one end. It's a 2.2Megohms lin pot.
The frame timebase employs a Miller Transitron circuit. The line time oscillator is a more conventional blocking transformer circuit.

Plenty height now but just look at the width.

DFWB.

Andy Doz 24th Aug 2011 8:17 am

Re: Bush TV12 restoration.
 
I think you're inchining into the lead now ....

Does someone have a TV22MKI schematic or trader sheet I can borrow?

Cobaltblue 24th Aug 2011 8:25 am

Re: Bush TV12 restoration.
 
Try Dukes page here
Enjoy :thumbsup:
Mike T

Andy Doz 24th Aug 2011 8:35 am

Re: Bush TV12 restoration.
 
Quote:

Originally Posted by Cobaltblue (Post 459835)
Try Dukes page here
Enjoy :thumbsup:
Mike T

Unfortunately that's for a TV22A ..

HamishBoxer 24th Aug 2011 10:16 am

Re: Bush TV12 restoration.
 
Think your Frame Osc Tx could be o/c Andy.

David

HamishBoxer 24th Aug 2011 10:17 am

Re: Bush TV12 restoration.
 
Think i have MK1 sheet can scan and send.

HamishBoxer 24th Aug 2011 10:24 am

Re: Bush TV12 restoration.
 
Just send me a PM with email address and its sat here on my desktop ready to go!


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