Kenwood Basic C2 Project

Found IC2 has the same issue. instead of 18vdc it actually has -1.6vdc same on IC1
I also noticed that the high filter seems to have an opposite effect. It brings out more highs but it also sounds less clear?
 
Hello Nadude,

When you are ongoing with your recap please:

Change the C73/C74, the capacitor for the zener Diode, to 4,7 uF MKS2 Wima. Do the same with C81/C82 and C67/C68.

Change the out coupling condensers to Foil- Types. I change the C23/C24 to two times 10uF/50V Wima MKS2. 20uF is enough; there will be no problem with deep frequencies. That’s what I have done in the report on “old fidelity Forum”

Spend a little 4,7 uF Wima cap behind R111/R112 to ground. Similar to the other regulators.

Change the C07 (the cap for the zener D10) to 4,7 uF Wima MKS2

I changed the R61/R62 outgoing Resistor to 33 Ohm. It is your decision

God Luck with your rebuild of the Basic C-2


Richard
 
Thanks Richard.. I was looking at your thread after I was sent the link..... after I made a parts order...lol.

I have solved the last issue. It turned out to be that the culprit was Q25. It's working like a champ!
I can't wait to hear what it will sound like after the recap, better opamps and proper zener's!
 
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I have solved the last issue. It turned out to be that the culprit was Q25. It's working like a champ!

I can't wait to hear what it will sound like after the recap, better opamps and proper zener's!
Good news! Great preamp! :beerchug:

I'd replace the output relay, too. :thumbsup:
 
...I have solved the last issue. It turned out to be that the culprit was Q25. It's working like a champ!
I can't wait to hear what it will sound like after the recap, better opamps and proper zener's!

Congrats on the fix; looking forward to your thoughts on the restoration/upgrade.
 
Well, got the recap done! I am going to be giving it a thorough listening and give my thoughts. I mostly incorporated Leestereo's mods. I haven't had enough in the budget to try most of yours Richard, at a later date perhaps. I can't make too many Mouser orders.. :confused:
 
I know this is an old thread, but I just got my amp done that is paired with the Kenwood and I have an issue. At least I think it's an issue :confused:
The volume out of the C2 isn't what I think it should be. For regular listening I'm having to turn it up to at least the 12oclock position. I can go to full volume and it's not pegging the amp. Could this be due to going to the 16volt zener's in the line stage?
 
I know this is an old thread, but I just got my amp done that is paired with the Kenwood and I have an issue. At least I think it's an issue :confused:
The volume out of the C2 isn't what I think it should be. For regular listening I'm having to turn it up to at least the 12oclock position. I can go to full volume and it's not pegging the amp. Could this be due to going to the 16volt zener's in the line stage?
I doubt it's the 16V zeners. When I was testing mine I decided to tack 13V zeners on the ones at D11 and 12 to tame the voltage reaching the opamps. They lowered the voltage even further than the 16V ones would with no noticable decrease in volume output. Could be a ground issue.
 
Volume, balance, RCA jacks, ribbon wire connections... Did you carefully go over the solder joints with a magnifier to look for poor/heat stressed joints? If it's not a ground issue, you'll need to start looking at your gain-stage transistors. Mine, after full mods, doesn't have a volume issue. I suppose you could measure the voltage at the outputs and compare it to the spec sheet.
 
:lurk:

I have one of these preamps that I get sound at the headphones but can't get the outputs to go live.

I'm liking this thread. :thumbsup:
 
These have issues with poor solder joints at the RCA jacks. You'll need to check those first which requires some disassembly.
 
I'll double check everything.. I've been laid up recently so I haven't been able to do anything yet... planning on getting to it in a couple of days!
 
:lurk:

I have one of these preamps that I get sound at the headphones but can't get the outputs to go live.

I'm liking this thread. :thumbsup:

It's not that hard of a preamp to work on, and the results can be awesome! It sounds great just does not have the volume it should have!
 
The general consensus seems to be that, when compared to another C2 which the owner noted no problems with, that the "relative" position of the volume knob seems to provide a lower volume than what the user expected. Not that this is a problem with the unit, but that other units used seem to get louder more quickly than this preamp. I, for one, am glad I have to turn the volume knob a bit more "than usual" to get a loud volume than I do on other units, where I seem to barely turn the knob before it gets really loud.
 
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