Kenwood KA-400 bias and dc-offset.

I bought this amp for cheap. It was in pretty poor condition. Faceplate was awful...paint spots all over.....and some yellow stuff that can't come off....plenty of gunk inside...2 blown caps......LEFT side tr's blown...both fuses blown.

Anyway.....as it is a decent amp, I decided to see if I could save it. I recapped the unit...big filters too.....changed all main tr's to NOS. Drivers were changed to ksc2690/ksa1220. I cleaned the unit inside. DBT'ed.....bright...dim..relay clicked.....all ok.....normal power...also fine. Connected speakers...good sound both channels.

Dc-offset was measured at the speaker terminals, no input, no vol., AUX...both channels adjusted easily to 0v. The heatsinks did get hot.

Now.......with meters hooked up across the emitter resistors(0.47 ohm)...LEFT channel measured 120mV....RIGHT channel 160mV...I then
adjusted vr5/6 to minimum.....LEFT channel 64mV....RIGHT channel 104mV.
It can't go lower than this...........as the scat' I have is really bad....can a fellow tell me what the bias should be. I am guessing 25-30mV.

The bias driver is a 2sa899(?)......should I change it?

Thanks.

Any ideas on the bias setting? Thanks.

Have you still got this amp? I am fixing one up. I have half of the service manual, going to look for more. mine had a failed repair attempt i think, it blew up when i plugged it in but it's in great shape. I'm going to fit the same as the original transistors,on mine the SEPP drivers failed or at least 2 of them, perhaps because of the replacement transistors that were some type of equivalent at 5v switching rather than 6v. The SEPP are 2SC1735 and 2SA850 I ordered 10 of each if you need any.
For the pre you have the correct number 2SA899 (B,V) as it's written. I think i checked mine and seemed ok on the tester but i might keep an eye on them as i power up. Once i removed those and the finals the protection kicked off, most of the faults are under control but there are still voltage differences on the two sides. I need to look a bit deeper.

The finals are 2SA1103 & 2SC2578 if anyone was wondering. I also ordered a load of those.
WOndering why you chose the transistors that you did and if they ended up working well for you?
I think you will be good around 30mv on the bias but i'll let you know when i find the spec.

I found this which is a slightly different version and this one uses 20mv but i would set them around 30mv after 10mins of being switched on no music playing. On the big bias resistors there are 3 test points, connect to the outside two on each resistor, they might need a bit of a clean up to get a good connection.

https://medias.audiofanzine.com/files/hfe-kenwood-ka-305-3055-service-474941.pdf