Harman/Kardon HK6500 balance misalignment

[rolilohse]

Hi all,

I am quite happy with my HK6500 for almost 15 years.

Recently I noticed that the left channel has a lower output than the right one, this misalignment varies from time to time so that compensating with the balance knob is quite troublesome.

This failure is indipendent on the listening level, it stays the same for all volumes.

I performed following checks:

- Balance and volume potentiometers work well.
- Speaker switch works fine without any resistance.
- DC offset and idling current are adjusted according to the service manual.
- Applying a signal direct to the power amp lead to the same result, so the fault must lay in the power amp section.
- Surprisingly this effect only occurs when listening via speakers, when listening to headphones attached to the headphone jack both channels have the same level (the Stax headphones I use are connected to the speaker output, so here the balance is misaligned as well) - this failure seems to be dependend on the load attached to the power amp.

Any help is appreciated.

Roland

 

[Netlist]

Did you try reversing your speakers?

/Hugo

 

[rolilohse]

Did you try reversing your speakers?

/Hugo

Bingo, that was the answer! What a bummer that I did not get it:

I used my Stax headphones as a reference - and they seem to have a problem with the left channel.

As an side effect my amplifier is now cleaned inside & the DC offset is adjusted .


Cheers Roland

 

[Netlist]

Blame Murphy for the headphone problem. So, perhaps we'll meet again in the speakers forum.

/Hugo

 

[annas]

Hi everybody, I hope you can help me with some advice

I recently bought a second hand Harman Kardon hk6500, but to my big disappointment the left speaker volume is way lower than the right one. The issue is the same for both speaker A and B input channels.

I have a friend that says that the left channel is ruined and that it can't be repaired.

Would you agree with this, or is there anything that can be done?

Thanks!