soldeerbout
New Member
Another Kenwood KA-3500 with some issues
Hi All!
First post here at AK.
I’m doing a restoration on a Kenwood KA-3500 (European model) and could use some technical advice.
The problems:
1. There was a lot of distortion at both channels when volume is turned up. (solved)
2. When you turn on the amp you hear a loud scratchy sound, volume knob does not effect the amplitude, its only on the right channel, and lasts about 4/5 seconds
What i’ve done so far:
- Cleaned the knobs and switches
- Replaced the powercaps (problem 1. solved) and a few small capacitors around the rectifier. C27 t/m C31
Now I’m trying to locate problem 2. It must be in the poweramp section (or powersupply??) because I disconnected the right channel signal wire between preamp and poweramp (blue one), problem was still there. Further more, there are no sources connected. When you switch the power on and off fast, the problem does not occur. Also when you switch-off the amp and then turn up de volume, the sound is there for a few seconds.
This amplifier does not have a delay relais for the speakers to get signal. Somebody told me that there is circuit on the poweramp board that has to have this function, anybody know more about this on the KA-3500?
Really like to get this puppy going again, first try and solve the problems and then do a total recap.
Hope you Guys have some helpful thoughts on this one.
Thank you in advance.
Hi All!
First post here at AK.
I’m doing a restoration on a Kenwood KA-3500 (European model) and could use some technical advice.
The problems:
1. There was a lot of distortion at both channels when volume is turned up. (solved)
2. When you turn on the amp you hear a loud scratchy sound, volume knob does not effect the amplitude, its only on the right channel, and lasts about 4/5 seconds
What i’ve done so far:
- Cleaned the knobs and switches
- Replaced the powercaps (problem 1. solved) and a few small capacitors around the rectifier. C27 t/m C31
Now I’m trying to locate problem 2. It must be in the poweramp section (or powersupply??) because I disconnected the right channel signal wire between preamp and poweramp (blue one), problem was still there. Further more, there are no sources connected. When you switch the power on and off fast, the problem does not occur. Also when you switch-off the amp and then turn up de volume, the sound is there for a few seconds.
This amplifier does not have a delay relais for the speakers to get signal. Somebody told me that there is circuit on the poweramp board that has to have this function, anybody know more about this on the KA-3500?
Really like to get this puppy going again, first try and solve the problems and then do a total recap.
Hope you Guys have some helpful thoughts on this one.
Thank you in advance.
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