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Thursday, 17 January 2019

Linn Klout - one channel down.

More Linn !

This time it's a Klout (where do they think these names up?!)


As you can see from the photo, the left channel is just showing a red LED, and has no output.

First off remove the top...

We're going to need to remove the left hand amplifier board to inspect and repair...









... which takes a lot of disassembly!

Disconnect the transformer, and the remote switching board. Unscrew the single screw securing remote input socket from the baseplate (you can leave it attached to the rear panel). You can now remove the baseplate, remote switching board and transformer.

Unscrew the input socket for the board we want to remove from the rear panel, and remove the two long cap screws that secure the output sockets. The cap screws are located in between the heatsink fins. There are 6 more cap screws securing the output transistors heatsink block, and the board itself to the heatsink. Remove these. You can now wiggle the offending board from the chassis.


Cursory checks on the board show all 4 output transistors to have failed leaky. A sanity check with the good channel confirms this.

There are two pairs in parallel. Two 2SC3519's and two 2SC1386's. Thankfully these are still available at the time of writing, so are duly ordered up. Driver transistors Q20, Q21, Q22, Q30, Q31, Q27, Q26 and Q25 check OK

The ESR of the electrolytics are checked. There are six 100uF 63V caps, two 220uF 16V on each board. They read OK'ish, but not great, so are replaced. The main smoothing caps all read sub 0.01 Ohm, and are not replaced.


The small sub-board has two 68uF 16v caps on the top. They read almost open circuit! Replaced.

Once this channel is repaired, I'll re-cap the other as it won't be far behind failing!









The transistors are held to a heat spreader by these two nuts. Removal is fairly straight forward. Clean all the old, dried up heatsink compound form the spreader with some IPA.









Heatsink compound is cleaned off the heatsink, and a smear of new compound applied.











And the board squeezed back in place!












I reassemble the amp, just to test the freshly repaired channel before re-capping the good one.

It's good news.









All boxed up, tested and good for another 20 years :)












2 comments:

  1. Hi Doz, I have the exact same issue with my Linn Klout. Do you do repairs?

    ReplyDelete
  2. See "not a business" on the right hand side. Thanks.

    ReplyDelete