AKG solid tube PSU failure !

Help Support GroupDIY:

MartyMart

Well-known member
Joined
Feb 28, 2006
Messages
2,340
Location
Berlin for a while
Anyone have any experience with this PSU ?
It belongs to a friend and is blowing the fuse constantly, the PAIN is that to get
to the bottom of the board you almost have to destroy the case as all the
sockets are mounted and protrude over the board and are riveted onto the
case from the outside !!
Not a screw in sight !

ANy known issues / tips are very welcome.
It's very hard to test out and even look at the traces until it's all out of this
stupid case.

MM.
 

mrclunk

Well-known member
Joined
Nov 29, 2006
Messages
1,095
Location
London
i repaired one for a mate a while ago, i think there's a know problem with the power transformer, i had to buy a new one.
i should still have the details at the studio somewhere, i'll have a look tomorrow.
 

MartyMart

Well-known member
Joined
Feb 28, 2006
Messages
2,340
Location
Berlin for a while
Thanks that would be great, I wondered if it was the traffo as there's no
obvious signs of any other component damage, it's a quite cheap looking
grey lump and PCB mount too, which seems odd !!

Cheers,
Marty.
 

rodabod

Well-known member
Joined
May 12, 2005
Messages
2,896
Location
London
Check the obvious things frist; shorts from HT and heater to ground.

If you suspect the power trafo, lift the secondary and see if it still blows fuses.

Roddy
 

mrclunk

Well-known member
Joined
Nov 29, 2006
Messages
1,095
Location
London
found some old emails with stuff about the fix.

It had blown the protection VDR's, the inductor and the transformer was cooked.
The dodgy transformer was grey, the new improved is brown.

i ordered the bits from Cimple spares

2 x 0012 E 0038 ( 130V version) RV1 /RV2
1 x 0022 E 0036 Transformer ( brown housing ) TR1
1 x 0023 E 0089 533mH coil, L1.

also in an email from an AKG repair guy:
'Please note, the fuse rating on the power supply was later revised to
T200mA.'

think the schematics on the akg site.
 

mrclunk

Well-known member
Joined
Nov 29, 2006
Messages
1,095
Location
London
heres the service doc

http://www.akg.com/mediendatenbank2/psfile/datei/37/solidtube4055d251a2cd0.pdf
 

MartyMart

Well-known member
Joined
Feb 28, 2006
Messages
2,340
Location
Berlin for a while
Thanks, I did find it on the AKG site, do you have any idea of the cost of those
replacement parts ?
I need to give my mate an idea before I go ahead and repair it.

Many thanks for your assistance,

Marty.
 

mikeyB

Well-known member
Joined
Apr 12, 2005
Messages
505
Location
Manchester UK
[quote author="mrclunk"]cost me £48.56[/quote] :shock:

Whoa there :!:

Get in touch with www.saturn-sound.com. I've fixed 3 solidtubes - all psu faliure (transformer). It's a while since - but each tx cost £25 shipped to Manchester.
He's called Ashley Styles - a very nice man - very helpful - and some nice bits to sell also!
Hope this helps.
 

MartyMart

Well-known member
Joined
Feb 28, 2006
Messages
2,340
Location
Berlin for a while
Mikey, that's a price for the Traffo, coil and RV1&2 so the traffo alone is
probably around the £25 area.
I get a dead link from the saturn site BTW

Marty.
 

Sorr

Well-known member
Joined
Sep 16, 2005
Messages
250
Location
Australia
In the end I rebuilt it in a new case with a new (non AKG) transformer.
This is after I rebuilt the microphone and repaired the PSU twice!
Isnt there some comment about Harmon around this forum?
 

mikeyB

Well-known member
Joined
Apr 12, 2005
Messages
505
Location
Manchester UK
[quote author="MartyMart"]Mikey, that's a price for the Traffo, coil and RV1&2 so the traffo alone is
probably around the £25 area.
I get a dead link from the saturn site BTW

Marty.[/quote]

Sorry Marty - put . after com - try
www.saturn-sound.com

Should work

Only the traffo was fooked in the 3 I fixed. Just had one I fixed back on the bench - the mic cable had been broken! - fixed it and still going strong.

Mike
 

barney

Well-known member
Joined
Sep 22, 2005
Messages
102
Location
Melbourne Australia
+1 for replacing the psu transformer. AKG distributor had them in stock which made me think this was more than a one off. Hope I don't see it back on the bench too soon.
 

MartyMart

Well-known member
Joined
Feb 28, 2006
Messages
2,340
Location
Berlin for a while
OK, well he's decided to have AKG fix it for £90 including VAT and the
postage in/out so that's not a bad deal and saves me "futzing" with that
stupid case for an hour or two !!
There would have only been £20 in it for me anyway.
Thanks for all the helpful links etc guys.

MM.
 

Rob Flinn

Well-known member
Joined
Jun 3, 2004
Messages
4,557
Location
Sussex, UK
I have one of these on the bench at the moment, doing what you describe.  Initially it was obvious that the varistors had gone, which I replaced, gave it back to it's owner, it was fine for 8 hours, but then started blowing the fuses again.  I replaced the varistors again & same thing happened, all fine for several hours then pop !

The PSU has the grey mains transformer.

Does this sound like what the problem was for you guys ?    Time to replace the mains transformer ???
 
Top