Kenwood KA-4040R stereo amp. L Channel week

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Almantas
Neuling

#1 erstellt: 25. Jun 2024, 10:00

Hallo, thank you for this post. I'm new here, so let me introduce myself briefly - I live in Vilnius, Litauen.

Recently my friend gave me this Kenwood KA-4040R which was in his garage for a couple of years ..

I found that the two capacitors were leaking and had damaged 4 inputs.

After the change of 16 diods and two capacitors 3300uFx10V it also appeared that one channel Left is twice weaker than Right.

Any ideas about what can be wrong and where to start?
Maybe someone has schematics of this amplifier?

Sorry, the post is not in German, I know only a few words though I was in Manroland printing machinery training in Plauen several years ago ...

Best regards Almantas

Valenzband
Inventar

#2 erstellt: 25. Jun 2024, 10:20

Welcome to the nerds ;-) There are numerous free service manuals on the Internet, for example

https://manualmachine.com/kenwood/ka4040r/3245989-service-manual/. Simply enter the device name and the term "service manual" in a Google search if you need such information further on.
You should start by checking all DC voltages indicated therein and possibly more (AC levels...) with the appropriate equipment.
Based on your description I would search for bad contacts or broken connections (corrosion, solder joints).

An appliance that has been sitting in the garage for years is something of a recipe for corrosion problems on contacts, solder joints and so on.
Up in Lithuania winters may be cold enough to freeze water-based electrolytics (caps). These also die often from years of neglectance (no voltage applied, de- formation), however

[Beitrag von Valenzband am 25. Jun 2024, 10:21 bearbeitet]

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