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Kenwood KA-1000 vintage super-integrated- The Age Of Plastic...

That heat pipe arrangement reminds me of an amp I bought while out at school in the States - a Sony TA-F55. I'd been working on a building site for the holidays and there was stereo store on my cycle ride back home. I would sometimes drop in and dream of owning some of the kit on display. On my last day of working on the building site, with my pay in my pocket, I again dropped by the store and ended up buying a Sony TA-F55 which was being discounted to make way for something new and not quite so interesting to my eyes. The Sony was a good looker and very slim - supposedly the slender profile achieved thanks to the use of a heat pipe. It was a good little amp that lasted me a few years, although the light behind the volume indicator gave up not long after the warranty expired..
 
I had a Sanyo P55(I believe it was), that had cooling very similar to the above. Sometimes after a nice long listen at higher levels than normal, during quiet passages of music, you could hear the "bubbling" in the pipes as it did its thing. I also had the matching preamp and tuner, was a nice combo really for the day.
 
Hello

I have a problem with unstable offset in Kenwood Ka 1000 Sigma Drive, on cold start about 100 ~ 140 Mv after 10 minutes it shifts in the range of -30 ~ 30 Mv in both channels, the differential pairs were replaced with the same 2SC535 with no effect, transistors Q35, Q37, Q36 , Q38 (2sa912) changed to KSA1142Y with additional radiator cooling and Q39, Q40 (2SC1885S) changed to KSC2690A-Y, offset potentiometers were also replaced, entire bottom plate received new solders. What could be the problem with this behavior of the amplifier? Could the fact that it is 220V (currently 240V) be a problem in the power supply section? the main capacitors are 63V, does that have anything to do with it?
 
Hello VanDerGraaf! Thank you for your response. My Ka 1000 also sounds very beautiful, but I have a problem with the offset, according to the diagram it should be close to 0Mv, these values of about 30Mv are still safe for the speakers and do not cause distortions, but I would like to improve it. Your photos are missing these elements, diodes, resistors connected to each other, is this some kind of modification, what did the repair of the silencing board involve? Regards

 
I play on Usher Be 718 and it sounds great, I also use Sigma 0.5mm Jantzen Solid Core cables for Chord Clearway X speakers, it's strange that such an old amplifier can play so well, the sound is tight and detailed, better than many newer amplifiers for a lot of money ! I'm from Poland.

 


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