Kenwood L-07M Restoration (1)

[rickl]

https://www.hifiengine.com/manual_library/kenwood/l-07m.shtml

 

[Broesel02]

Very fine Work. Gratulation!

I use other Caps for the rectifier Board - and other Diodes



for the trimmers for offset and bias i use spindetrimmer, it is easier to adjust them



I wish great sound for you with your new Amps!

Richard

 

[bimotarich]

Great work! You are making me want to dig mine out of the closet and put them back into service! I am sure they at least need their bias and offset adjusted…

 

[Martin 530]

Hey all,

I figured I would post some updates on the restoration of my L-07M monoblocks.

When I first got the L-07M's, I used them on and off for a few months before getting them serviced by my tech in MA. Apparently, he only replaced the capacitors that measured out of spec.

They have been working phenomenally for the past ~3 years, but since then, one channel has developed a slight indeterminacy when the input wire is jiggled.

I opened the amplifier up and re-soldered the wire leading to the input jack. Problem solved.

While in there, I noticed that a majority of the caps hadn't been changed, and that many of the larger caps are glued to the board with the notoriously bad brown corrosive glue. I also saw some of the PCB jumpers, as well as a couple resistors,
which were located near the glue, were starting to corrode slightly. I removed the resistors and measured them. They all measured fine, so I cleaned the leads and re-installed. I'm thinking about changing all of the suspect resistors in both amplifiers.

I currently have a large order coming from Mouser, including basically every cap in the amplifiers, excluding the large Elna filter caps, and the large 470uf 100v axial caps on the power boards. I also have both relays for each amplifier coming as well.

I recently was able to find the original service manual for the L-07M's on eBay, so I have been referencing it quite a bit. It goes into detail on how to separate the power supply section from the rest of the amplifier, and how to disassemble the whole thing
down to the frame. It's really quite handy. Kenwood/Trio seemed to have been very dedicated to making the disassembly of these amplifiers a walk in the park. Every part of these amplifiers is modular, except where some of the power supply board's wires are soldered to the main board.

I'm still waiting on the Mouser order, which should be here this Tuesday.

I'll include some pictures of the preliminary tear down that I took while gathering a parts list / inspecting the amps.

I'll also update this thread as I go along. I'm also open to suggestions on modifications and recommendations for these amplifiers as well. Thanks for reading along.

Connor
View attachment 1793357 View attachment 1793358 View attachment 1793359 View attachment 1793360 View attachment 1793361 View attachment 1793362 View attachment 1793363 View attachment 1793365 View attachment 1793366

I realize this post is older.
I have these also and need one repaired
Can u help me ?

 

[rickl]

I have these also and need one repaired
Can u help me ?

Martin, I'd use the search button above and read up on the many resto threads. The resto sticky may even have links to some.

This should help you get familiar with known issues and fixes.

When I did mine, I had some assembly glue problems.

Also, any help would require knowing if you have the model II (2?) or original ones. I think they have there own problems.

They are nice and worth getting fixed.