Need help for bias adjusting for hybrid amplifier KORA ARIES

[Lynyrd]

Hello.
Need help for bias adjusting for hybrid amplifier KORA ARIES.
It's 2 resistors RV1 & RV2,but any ideas for value and test points.

Thank you.

Service manual

https://acrobat.adobe.com/id/urn:aa...mment_id=d334b95b-cf62-4fc5-8eb8-6fada25d6ce8

 

[petertub]

Something wrong with this manual. How about posting a proper pdf ?

 

[Lynyrd]

https://www.cjoint.com/doc/24_09/NIAibKRsj6y_kora-aries-sch.pdf

 

[euro21]

The value is in the schematic: both of them 10k trimmer.
See blue helitrims near the heatsink.
RV1 sets the symmetry of output stage: OV on output.


http://depanne-audio.blogspot.com/2015/12/ampli-kora-aries.html

 

[Lynyrd]

Хорошо для RV1.
And RV2?

 

[Lynyrd]

Ok for RV1.
But RV2........

 

[U102324]

RV1 sets bias current, RV2 is used for off-set adjustment. A little bit of a weird arrangement.

 

[euro21]

RV2 only for the regulated current source of virtual (depends of raw DC +50V) common point R25-R26.

 

[Lynyrd]

Ok and what is normal value on r25...r26

 

[Lynyrd]

Ok it's solved 9.5mV on resistor

 

[Lynyrd]

But I have two kora with similar problem.
The sound is low and distorted.
I think the tube alimentation is bad.
Can you help me for verification of voltage on lamp socket.
Across pin 4 & 5 15v AC it's ok.
The 2 tubes are new.

Service manual on first post

 

[Lynyrd]

 

[Lynyrd]

the lamps are very dim

 

[Lynyrd]

On pin 1 230v DC
On pin 6 230v DC.......

 

[Lynyrd]

Pin 3.....-5v
Pin 8.......-5v
Pin 2.......-3.12v
Pin 7.......0v

Tested without tube

 

[Lynyrd]

It's is normal -3.12v on pin 2?