Harman Kardon 930: Distortion

[davstev]

Hi All,

I am presently tinkering with a H/K 930 that has been awaiting attention, and it's sounding...not great.

Deoxit has been thoroughly done, it's definitely not that.

When I run a CD player into the AUX 1 or 2, I get major distortion, equal in both channels. Same in Radio mode. This is at a low to mid- volume, not high volume.

it's still outputting sound, it just sounds really crackly with very flabby bass. Classic 'distortion' sound. Ideas as to what's causing this? How to troubleshoot?

I've switched speakers and the problem persists. Problem is much less evident with headphones.

Is it an issue with the output stage somehow?

Thanks for ideas.

David

 

[avionic]

Seperate the pre-amp from the power amp .( jumpers on rear panel) Then use and alternate pre-amp or power amp to eliminate one or the other as possible sources of the distortion..

 

[avionic]

I get major distortion, equal in both channels

Looks like power supply B3 is common with both channels in the pre-amp and phono pre-amp.

 

[ivandezande]

Maybe a really dumb question, but is the bias set to spec and staying fine?

 

[davstev]

Blown speaker protection fuses! Both blown. I didn't know that a signal could still be sent when the fuses are blown, but now I know. Signal is sent to speakers, it just sounds like garbage. $4 later, I am back in business.

Thanks for the ideas.

David

 

[avionic]

Blown speaker protection fuses! Both blown. I didn't know that a signal could still be sent when the fuses are blown, but now I know. Signal is sent to speakers, it just sounds like garbage. $4 later, I am back in business.

Thanks for the ideas.

David

I like easy fixes...