AKG N12 PSU

[dukasound]

Hi
I got one N12 from 1963. New!!!!! Serial No. 2070. Never touch and switch ON.
I measured voltage without mike (I havent C12) and I saw about 158V HT and about 32V on heating. What is excatly voltage off-load?.
Must I replace caps and any adjustment is necesary. Also I didnt anything touch. This is circuit with transistor for stabilize heater voltage. Where to find conectors?
Thanks in advance
Duka

Soon pics inside :grin:

 

[Jazzy_Pidjay]

:shock:

 

[gyraf]

There is no such thing as a voltage off-load on old mic psu's.

You need to power it up with a microphone to find out.

 

[Buttercup]

Wow what a find!
Used connectors are difficult to find but you might
get something cheaper from :

http://www.microphoneclones.com/indexUS.htm

HT should be 120v and heater 6.3 ( or 4v for AC701 ) - but you
probably know this - with the mic connected.

Be nice with a DIY mic.

Giles

 

[dukasound]

[quote author="gyraf"]There is no such thing as a voltage off-load on old mic psu's.

You need to power it up with a microphone to find out.[/quote]
Thanks
I find slightly higher voltage on heatings. I connect pin 4 and 9 of tube. There is a resistor for adjusting voltage with red-sealed screw connection and I will try it. I was thinking to not touch psu and check with another psu off load voltage. Maybe factory was adjust it. Is necessary recaping?
Duka

 

[gyraf]

..heater often needs to be adjusted with microphone AND cable in place to compensate for loss in cable..

 

[dukasound]

[quote author="Buttercup"]Wow what a find!
Used connectors are difficult to find but you might
get something cheaper from :

http://www.microphoneclones.com/indexUS.htm

HT should be 120v and heater 6.3 ( or 4v for AC701 ) - but you
probably know this - with the mic connected.

Be nice with a DIY mic.

Giles[/quote]
Giles, Clones are expensive :?
I know voltages but I have no C12 to check
Duka

 

[dukasound]

[quote author="gyraf"]..heater often needs to be adjusted with microphone AND cable in place to compensate for loss in cable..[/quote]
Yes, I used C28 cable friend of mine.
RECAPING????

 

[Buttercup]

Caps are probably fine.
Have you opened it up to have a look?
Post some pics if you do and measure them to
see.
Shoud be 4x 50uf 350v or 2x dual 50uf.
If the thing has never been used I'm sure they
will be fine but someone will chime in if I'm
talking rubbish.

 

[Gus]

I would sell it for as much money as I could get from a Collector I would not touch it or adjust a part in it.

With modern parts you can build a better supply IMO.

 

[soundguy]

Im with gus, that supply is worth a bunch of money if you advertise it properly. Take the money and put it towards a modern supply that will make your mic sound better.

dave

 

[dukasound]

[quote author="Buttercup"]Caps are probably fine.
Have you opened it up to have a look?
Post some pics if you do and measure them to
see.
Shoud be 4x 50uf 350v or 2x dual 50uf.
If the thing has never been used I'm sure they
will be fine but someone will chime in if I'm
talking rubbish.[/quote]
Everything is OK. Not touching. All parts original.
Very strange rectifier, original transformer, big variable resistor and
very shiney inside.
I havent camera now but I will post inside pics.
Duka

 

[dukasound]

[quote author="Gus"]I would sell it for as much money as I could get from a Collector I would not touch it or adjust a part in it.

With modern parts you can build a better supply IMO.[/quote]
I agree (also all time I havent mush money for project what I like to do).
What can be price for this?
Duka