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

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.

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.

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

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?

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

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

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.

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.

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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