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Technics SE-C01 power amp
Technics SE-C01 power amp
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Old 17th July 2015, 12:13 PM   #1
Carlosraj is offline Carlosraj  United Kingdom
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Join Date: Jan 2010
Default Technics SE-C01 power amp

Dear Friends,

I am working on this amp that belongs to a friend. It comes in 3 units which are compact, very much smaller than normal units. It consists of (1) SU-C01 the preamp (2) SE-C01 the DC power amp and SH-C01 the power supply unit. The preamp has its own power supply but the power supply for the power amp comes from the SH-C01. The amp works OK, the problem is, as I increase the volume some where about half volume onwards the power amp cuts. I can heard the click and the sound goes off. This is the first time that I came across this sort of problem. I checked for DC in the outputs but none.
I would be very thankful if someone could advice me on what could be the problem. Could it be the power supply. Please assist.

Thanks

Carlos
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Old 18th July 2015, 06:12 PM   #2
sgrossklass is offline sgrossklass  Germany
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Join Date: Nov 2004
Location: Germany
*downloads docs* That's a bit of an odd amp. Input Gnd connects to chassis via a polar electrolytic (!). You can probably guess what that means after 3.5 decades. A new low-leakage part would seem in order there (does anyone still make quality bipolars? otherwise use two low-leakage ones back-to-back if need be).

Anyway, the input seems to be DC-coupled. It would thus seem likely that the preamp SU-C01 produces a variable DC offset. Smells like leaky coupling caps. Both C307 and C317 or right-channel equivalents must be leaky for this to happen. It's probably about time for a complete recapping job, at least around the EQ amp, where there are just a few to begin with. Note C317/318 are given as bipolar, probably because they are barely ever seeing any DC and should keep off any kind of DC voltages in case of a fault.

There's a remote possibility of oscillation being involved, too. Funny things can happen if the power amp gets into preamp supplies, though I don't see how that should be happening here.

Like I said, consider a complete recapping job. Section by section, not all at once, but I guess you know that. And low-leakage around pots, of course.

EDIT: Looks like at least Nichicon still make good nonpolars, though I'd check dimensions first.

Last edited by sgrossklass; 18th July 2015 at 06:19 PM.
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Old 7th December 2017, 05:41 AM   #3
inakaguy is offline inakaguy  Japan
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Join Date: Dec 2017
I have one of these and I'm considering having it refurbished. Can either of you give an opinion on the value of a refurbished SE-C01 / SU-C01 system vs something I could buy for the cost of having it refurbished? Thanks for any opinions...
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