Author Topic: Kenwood KA70 left channel playing extremely soft  (Read 760 times)

Offline THE_STIG

Kenwood KA70 left channel playing extremely soft
« on: November 13, 2017, 07:40:23 AM »
Hi all, so over the weekend my trusty ka-70 started acting up. When playing, the left channel is very soft, you have to have the balance dial sitting at 9 o'clock for it to sound more or less balanced. It sound pretty much normal like this, there is no distortion i can hear but obviously something must have died.

Switching to mono brings both channels to the same level again, switching on loudness also helps matters a bit but the right channel is still a bit louder.

Doesn't seem to be an issue with the source, tape, aux, phono, tuner etc... all produce the same result.

Anyone had something similar happen, what should i check first?

Offline Family_Dog

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Re: Kenwood KA70 left channel playing extremely soft
« Reply #1 on: November 13, 2017, 03:09:06 PM »
Sounds like caps drying out. If the Kenwood uses those grey Suzuki caps, chsange them.


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Offline KOD

Re: Kenwood KA70 left channel playing extremely soft
« Reply #2 on: November 16, 2017, 10:36:26 AM »
Apart from the phono pre-amp, all other inputs on the KA-70 are passive prior to the stereo/mono switch.

As a start I would liberally clean all the selector switches with Kontakt 60 or similar and if the imbalance persists would then look for old caps.

kod
 
Grundig/Eddystone/B&O/Montgomery Ward/NAD

Offline THE_STIG

Re: Kenwood KA70 left channel playing extremely soft
« Reply #3 on: November 26, 2017, 11:32:55 AM »
Thanks all. Got it sorted

Went ahead and replaced all the caps(Japanese made of course), besides the two main filter caps. The problem remained though. After looking closely at the circuit diagram i took the volume control pot out and tested this, sure enough the center tapped pin which should read a constant 50k was reading infinity on the pot used for the left channel. Since i didn't have any luck finding a dual 100k pot with a 4th pin for the center tap, i cut that pin off and hacked in a a 50k resistor.

working 100s now ;D

Offline itscraig

Re: Kenwood KA70 left channel playing extremely soft
« Reply #4 on: November 26, 2017, 11:36:48 AM »
nicely done, where are the pictures?
love to see these things

Offline Raj Nair

Re: Kenwood KA70 left channel playing extremely soft
« Reply #5 on: December 11, 2017, 06:58:42 AM »
common fault age caps transistors

Offline HBAutomation

Re: Kenwood KA70 left channel playing extremely soft
« Reply #6 on: December 11, 2017, 09:53:04 AM »
^^  :flyswat:
When You Come to a Fork in the Road, Take It!            [Yogi Berra]