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Old 2nd Jun 2018, 9:28 pm   #1
bill knox
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Default Advance J2 Audio Generator

Hi all

I need one of two thing please:

What the secondary AC voltage is for the HT

or

2 A scrap Advance J2 audio generator, my mains transformer has gone to it's happy hunting grounds, it's smoking like a trouper- big time

If anyone has or knows the whereabouts of a scrap gen or knows what the secondary voltage so that I can start looking for a replacement, I would be grateful.

Could any kind soul please PM me

Regards

Bill
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Old 3rd Jun 2018, 6:37 am   #2
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Default Re: Advance J2 Audio Generator

Schematic here - https://vintage-radio.net/forum/showthread.php?t=60414 it's hard to see the voltage figures but a lot of Advance sig gens have about 300/310v HT before the first dropper resistor ie R26. V4 is a EZ81, looking at the datasheet for a HT of 295v that would mean you need about 300v AC for the tfmr secs, so 300 0 300v,

Andy.
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Old 3rd Jun 2018, 11:04 am   #3
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Default Re: Advance J2 Audio Generator

I don't know if this is relevant but the schematic for the J1b & J2b gives the HT secondary voltages as 280-0-280.

Lawrence.
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Old 4th Jun 2018, 7:13 am   #4
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Default Re: Advance J2 Audio Generator

Hi!

Do a search for "50VA R Core Tube Transformer" - you can get one that's dual primary with a secondary of 250-0-250V and twice 6.3V, enabling you to use one isolated 6.3V for the EZ81, and allowing for the regulation percentage, I think one of these'd get your J2 up and running nicely!

They mount on a flat surface and I think there's an inter–winding screen as well!

Chris Williams
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Old 5th Jun 2018, 1:21 am   #5
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Default Re: Advance J2 Audio Generator

I think the first question I'd be asking is what has caused the transformer to fail - short on the HT rail somewhere? I don't think these are known for transformer failure. You've obviously already disconnected all the output connections from the transformer secondaries, just leaving the mains input, and it's still overheating and smoking?
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Old 5th Jun 2018, 11:17 pm   #6
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Default Re: Advance J2 Audio Generator

Hi!

Both Gordon J King in "Radio and Audio Servicing Handbook", 1970 ed., and C.A. Quarrington in CH. 6 of vol 3 of " Radio & Television", 1963 ed., emphasise that mains transformers should not run hot, drip wax or pitch, smoke, etc., if they're in good condition both on and off load, so if you've got a cooking one with no secondary leads connected you can confidently chuck it away!

However, if you don't mind an investment of about 60 send a PM to Ed Dinning – he does a first–class job of rewinds and did a super job of one from a Farnell DTS 12 scope for me!

(In fact I'll have to get him to make me another tranny as the first one he did disappeared with my last old car a year ago!)

Chris Williams
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Old 6th Jun 2018, 5:48 am   #7
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Default Re: Advance J2 Audio Generator

Bill, I will have a look around. Can you post a picture of your txfmr? Dimensions as well. That will give me some idea.
Rob
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Old 6th Jun 2018, 9:17 pm   #8
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Default Re: Advance J2 Audio Generator

see post 4. I have a transformer like that. FOC but you would have to collect from Welwyn Garden City.
PM me if you are interested.
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Old 7th Jun 2018, 6:51 am   #9
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Default Re: Advance J2 Audio Generator

No word from Bill, maybe he got sorted. For valve regulated HT Lawrence I think is nearest with 280v secs, 250v will be a tad too small Chris. If you ditched the EZ81 a sec of 0 - 220v ish will give you 300v. Something like a small isolation tfmr.

After the fault has been found of course, good point Techman.

A.
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Old 15th Jun 2018, 12:21 am   #10
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Default Re: Advance J2 Audio Generator

Hi Peter

Sorry I have not been in touch since collecting the transformer, just about the right amount of space to fir it, it works perfectly many thanks

Regards

Bill

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