Bush TV12 restoration.
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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. |
Re: Bush TV12 restoration.
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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 :)
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Re: Bush TV12 restoration.
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David. |
Re: Bush TV12 restoration.
I would turn the brightness down on that!
Peter |
Re: Bush TV12 restoration.
Following my policy of Glasnost (openess) I can report that the line timebase has packed in.
DFWB. |
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. |
Re: Bush TV12 restoration.
Has war broken out in the vintage community?
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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. |
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.. :( |
Re: Bush TV12 restoration.
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A few caps. Repair the top cap on the line output valve ... and up with the volts!!
... there's all to play for. |
Re: Bush TV12 restoration.
Nice to see the tube 'smiling'!
You know you're well on your way at that stage! Greg |
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 |
Re: Bush TV12 restoration.
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Some pictures. The broken valveholder tag can been seen.
DFWB. |
Re: Bush TV12 restoration.
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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. |
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? |
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Re: Bush TV12 restoration.
Think your Frame Osc Tx could be o/c Andy.
David |
Re: Bush TV12 restoration.
Think i have MK1 sheet can scan and send.
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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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