This seems to be a common design issue with many HK units, including this one.
There are a few switches that tick or pop when used. Sometimes more than other times.
I get a big pop when using the tone defeat switch, but only if I just turned the unit on.
There is usually a tick when switching to AM.
There is a tick when using the treble cut switch.
Are there any tweaks I can do to prevent this? I've tried reducing some of the signal path capacitor values, HK seems to like making their cutoff frequencies crazy low.
Power amp input capacitor was changed to 4.7uF.
And in the preamp, I tried changing C6/C33 to 4.7uf (from 47). And then C13/C40 to 4.7 from 100uF. Both are highpass filters with a 100k resistor. This should give a cutoff frequency of 0.34Hz, right?
Service manual is attached, preamp is on page 17. Does anyone see any glaring issues?
There are a few switches that tick or pop when used. Sometimes more than other times.
I get a big pop when using the tone defeat switch, but only if I just turned the unit on.
There is usually a tick when switching to AM.
There is a tick when using the treble cut switch.
Are there any tweaks I can do to prevent this? I've tried reducing some of the signal path capacitor values, HK seems to like making their cutoff frequencies crazy low.
Power amp input capacitor was changed to 4.7uF.
And in the preamp, I tried changing C6/C33 to 4.7uf (from 47). And then C13/C40 to 4.7 from 100uF. Both are highpass filters with a 100k resistor. This should give a cutoff frequency of 0.34Hz, right?
Service manual is attached, preamp is on page 17. Does anyone see any glaring issues?
If the noises do not happen a short time after turning on, it's due to the circuit DC voltages settling down.
If they always happen, maybe some coupling capacitors are starting to leak. Also dirty contacts can cause some noise.
If they always happen, maybe some coupling capacitors are starting to leak. Also dirty contacts can cause some noise.
I'd replaced all the electrolytics. And it isn't the normal dirty switch pop. And the inputs are switch by IC chips.
The tone bypass control only does it badly when the unit has just been turned on, but the other switches that do it will do it at any point.
The tone bypass control only does it badly when the unit has just been turned on, but the other switches that do it will do it at any point.