Kenwood KA 7100 Offset and bias adj

[miklemke]

Does anyone have the procedure for adjusting the bias and offset on a Kenwood KA 7100??

Thanks

 

[Blue Shadow]

I have the KA-7300 and it is not adjustable based on my reading here at AK. A search may turn up the same for the 7100, but I'm not sure.


edit:
Corrected by Echowars.

 

[EchoWars]

The KA-7100 has adjustments for both, the KA-7300 has neither.

 

[ecluser]

Here is a link to a free schematic for the KA-7100

http://www.free-service-manuals.com/Audio___Hi_Fi/Kenwood/Kenwood_KA-7100_Schematic_Diagram_L36136/

Bias: Adjust VRe3 and VRe4 for 19mV between the two check point (C.P.) near the 0.47 Ohm resistors. (19 mV / 0.47 Ohm = 40 mA)

Offset: Adjust VRe1 and VRe2 for 0 V at the output

 

[miklemke]

Thanks for the info.

I see the two "CP" points for both channels for checking the bias.

Where do I check the Offset? I see VR1 and VR2. I would check between ground and what?

Thanks,

 

[BalancedXLR]

You measure the DC offset at the speaker terminals. Measure with no source connected, speakers disconnected, volume set to min, and the tone controls centred. DMM set to DC mV and probes attached to speaker terminals (make sure you have the appropriate speakers selected). Give the amp a good warm up period. After adjustments let it idle again and recheck both offset and bias.

 

[miklemke]

Thanks for the help.

Everything's dialed in and working well.