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Old 17th Dec 2018, 1:16 pm   #1
Jaguar1964
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Default Crypton Tuning Machine

Hi All

Let me start by apologising for this not being a radio topic and for it being written by an electronics novice

I recently bought an old Crypton Tuning machine from the 1960`s (I think) it's model No. BD120/FA6423 (this is a unit containing valves and a cathode ray tube)

Within this unit are two transformers and one of them is burnt out. The unit lights up and I would love to get it working to use on my old car

So here are my questions

1. Does anyone have a wiring diagram for this unit, or similar model/
2. Given it's burnt out could I tell the the transformer output voltages in any other way & seek a replacement? (input windings are 240V)
3. is it possible to get the transformer re-wound and if so what is the likely cost?
4. Do I have any other options?

All help will be gratefully received !!

Many thanks, Bijen
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Old 17th Dec 2018, 2:06 pm   #2
Radio Wrangler
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Default Re: Crypton Tuning Machine

Hello and welcome!

I used to use the model before that (round CRT)

1) I don't have a diagram
2) Tracing out the circuitry (it won't be terribly complex) will allow a reasonable guess at voltages.
3) yes, there are two people on here who regularly re-wind transformers and wind new ones.
4) It might be possible to count the turns while dismantling the old transformer and wind the new one from that.

Transformers are normally reliable beasts and just sit there inoffensively working. A burnt one may have a cause.

I think the EHT voltage for the CRT may be generated in a mains transformer. THese sorts of supplies can be quite dangerous if you are not very careful, and the high voltage winding might just be the site of insulation breakdown which starts the ball rolling. It may well have been killed by someone leaving it switched on overnight.

Discussion of electronic test gear seems admissible hereabouts, but you're best to steer clear of the things it got used on.

There should be an exhaust gas mixture meter under the roller door and a xenon strobe light.

David
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Old 17th Dec 2018, 3:15 pm   #3
Jaguar1964
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Thumbs up Re: Crypton Tuning Machine

Hi Radio Wrangler

Thanks for your reply

Mine also has a round CRT although it looks square on the front of the unit

I didn't realise it but I must be missing the exhaust gas mixture meter also I did think that the transformer failure may have an underlying cause but at least it's a start

Thanks again for the great advice, much appreciated !!!

Best regards, Bijen
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Old 17th Dec 2018, 8:34 pm   #4
Ed_Dinning
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Default Re: Crypton Tuning Machine

Hi Bijen, I scrapped one of those many years ago, but I think I recently sold the tube and screen assembly. Can you give me the approx. size of the transformer as I may still have that. Failing that I can rewind it.

You could also rewind it by carefully dismantling it and counting the turns/measuring the wire.

Ed
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Old 17th Dec 2018, 9:23 pm   #5
Radio1950
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Default Re: Crypton Tuning Machine

Hi Bijen,

How did you determine that the transformer is unserviceable please?
As Wrangler says, they are durable.
Maybe get it checked further?
Could save time and money.
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Old 17th Dec 2018, 11:33 pm   #6
Jaguar1964
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Default Re: Crypton Tuning Machine

Hi Ed & Radio 1950

The size od the transformer is aprox: 85mm x 65mm around the iron core & 85mm width ways across the winding`s

There are two transformers in the unit & Its the transformer that feeds the CRT that I need

Just to reply to Radio 1950 comments the unit did initially power up but but after a short while smoke appeared which seemed to come from the transformer and it quickly blew its fuses

with the transformer out of circuit the unit lights up but as soon as the transformer is connected the fuses blow

I guess there may also another underlining fault but in any event I think I will need a transformer swap / repair

Thanks again guys for your input

Regards

Bijen
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Old 18th Dec 2018, 9:29 pm   #7
Ed_Dinning
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Default Re: Crypton Tuning Machine

Hi Bijen, you could try running the CRT transformer with no connections to its output (secondary) side. If it then does not blow fuses, it could be an external fault.

Ed
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Old 18th Dec 2018, 10:29 pm   #8
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Default Re: Crypton Tuning Machine

These are very interesting old machines. However, just like radios of the period, if they haven't been in regular usage, or have been stored in damp conditions, some care needs to be taken when trying to bring them back to use.

You describe yourself as a novice Bijen, I wonder whether you may have just plugged this into the mains when you first tried it, or did you have a Variac unit so that you could slowly raise the voltage from 0 to 240V? The latter is much the best way to do it, if you plugged it straight in to the mains, that in itself may have caused damage. Hopefully, you now have it stored somewhere where it is as dry as possible. Any residual damp will risk problems with the EHT.

I know someone who worked for Crypton; I'll try find his contact details and see if he kept any manuals.

B
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Old 19th Dec 2018, 12:19 am   #9
Jaguar1964
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Thumbs up Re: Crypton Tuning Machine

Hi Baz.

You're right I'm afraid I plugged it straight in (I shall know better next time) and I do believe before I bought it that it was stored in a dampish garage, although it's in a warm, dry, conservatory now.

If your contact can advise on the Transformer voltages that would be great help and I can try to source another one or get this one re-wound

It's just such a lovely and quite rare thing it deserves to be saved and restored, also it's a bit of English technological history.

Thanks for the help.

Best regards, Bijen
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Old 19th Dec 2018, 10:25 am   #10
Dave Moll
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Default Re: Crypton Tuning Machine

Before rushing to replace the transformer, it may be well to follow Ed's advice above of disconnecting the outputs from the transformer to ensure that the problem isn't further "downstream". If you overload the output of a transformer, then the transformer will overload its power source.
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Old 19th Dec 2018, 5:57 pm   #11
Andrew B
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Default Re: Crypton Tuning Machine

Quote:
If your contact can advise on the Transformer voltages that would be great help and I can try to source another one or get this one re-wound
I would contact Ed Dinning on here, his guidance is very helpful and he may be able to rewind yours.
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