View Full Version : Kenwood Basic c2 balance adjustment pot


purenrg
03-18-2013, 12:07 AM
I have a Kenwood basic c2 with a bad balance adjustment pot is there anyone here that may know where to pick one up, or someone that works on or rebuilds these pots?

purenrg
03-20-2013, 08:14 AM
Well, I have started my on rebuild on my balance pot for the C2, man are the contacts Small in these potentiometers. we'll, see how it goes?

purenrg
03-21-2013, 12:53 PM
Rebuild Update, project was a success, but it was truly nerve racking job, I would not want to do it again anytime soon, and anyone that has ever done one of these before knows exactly what I'm talking about.
The Japanese should have used epoxy on these parts and this problem would not had ever occurred in the first place, I used JB Weld and it will never come loose again.

It was like operating on a Genia Pig!!!. Lol. the PIG still lives

matteos
03-21-2013, 06:15 PM
What did you do exactly? I'm picking up the same pre-amp tomorrow which has sound out of only one channel, googling shows this is a common flaw usually due to a bad balance adjustment pot, how did you go about rebuilding it?

purenrg
03-21-2013, 09:53 PM
I wrote up a guide but the this site kicks you off to quick before you can finalize?

matteos
03-21-2013, 10:16 PM
huh, not had that problem at all.. Well leave it for now, there's nothing more irritating than writing a whole thing out to just then lose it, maybe when I get it I'll just hit you up over PM for your help, if you don't mind?
CHeers!

purenrg
03-22-2013, 08:12 AM
This is the procedure I took to rebuild the balance potentmeter, I recommend that you skip on the coffee before starting this endeavor.

First remove cover and face plate from chassis this will allow access to the balance pot circuit board, there are two small screws & a retaining nut that holds this pot to the chassis.

Next you will see two aluminum retaining pins, these pins must be removed to dissemble the pot. Too remove the pins you will need to remove the splayed end that looks like a slot for a flat bladed screwdriver, I used a Dremil tool for this part to grind the splayed ends off. ( Only take off as little as possible of the pins) now try and drive the pins out of the body of the pot.

With pins out and metal backing tab removed you will see a mounting fiberglas contact pad, that is soldered to the little circuit board, this pad will have a hole in the center, this will need to be removed to access the "c" clip.

Now remove the "c" clip from the pot stem, this will give you access to the plastic rotor that the stainless steel contacts or mounted on, the contacts need to be reattached using an epoxy I used JB Weld, there will be one of these contacts on each side of the plastic rotor.

After this has been done you will reassemble the pot in the reverse order,so take your time because these parts are very {SMALL} especially the "C" clip,and contact brushes, you don't wont to loose them!!!!

Good luck, and pat yourself on the back and drink your self a beer when done because you deserve it !!!!!:banana:

qpagoda
03-22-2013, 08:23 AM
Is there a way to spray DeoxIt into the pot without taking it apart? I have a Basic C1 that needs to be worked through.

purenrg
03-22-2013, 08:55 AM
qpagoda, I tried to clean the contacts by doing that very thing, there is a very small hole that you can try and spray into, but it's a very... very small hole. More than likely the contacts have broke off the plastic rotor, if this has happened then this will not help.

I cant believe that these Japaneses engineers developed this part this way, they should have used a epoxy to attach these contact too the rotor assembly. and if you ever take one of these potentmeters apart and see how they did it, you will under stand how come these parts are failing :nono:

matteos
03-22-2013, 12:27 PM
This is the procedure I took to rebuild the balance potentmeter, I recommend that you skip on the coffee before starting this endeavor.

First remove cover and face plate from chassis this will allow access to the balance pot circuit board, there are two small screws & a retaining nut that holds this pot to the chassis.

Next you will see two aluminum retaining pins, these pins must be removed to dissemble the pot. Too remove the pins you will need to remove the splayed end that looks like a slot for a flat bladed screwdriver, I used a Dremil tool for this part to grind the splayed ends off. ( Only take off as little as possible of the pins) now try and drive the pins out of the body of the pot.

With pins out and metal backing tab removed you will see a mounting fiberglas contact pad, that is soldered to the little circuit board, this pad will have a hole in the center, this will need to be removed to access the "c" clip.

Now remove the "c" clip from the pot stem, this will give you access to the plastic rotor that the stainless steel contacts or mounted on, the contacts need to be reattached using an epoxy I used JB Weld, there will be one of these contacts on each side of the plastic rotor.

After this has been done you will reassemble the pot in the reverse order,so take your time because these parts are very {SMALL} especially the "C" clip,and contact brushes, you don't wont to loose them!!!!

Good luck, and pat yourself on the back and drink your self a beer when done because you deserve it !!!!!:banana:

:thmbsp::tresbon:

Thanks so much for the excellent write up!!!! picking up this preamp this evening.

I will observe the correct order of libations too :D

matteos
03-24-2013, 08:54 PM
Wow, this isn't easy, taking that pot apart was not fun. I have the c clip, it was already attached but I added epoxy anyway. There is only one of these c clips, it's on the front, on the back of the plastic rotor there is nothing.. I assume there should be something there?

matteos
03-24-2013, 09:00 PM
Well, I'm going to bypass the pot, I couldn't fit it back together properly and I snapped one of the fiberglass circles. Really is a fiddly little thing. I don't know much about working with electronics, but I think I figured it out from this German page. Danke! :tresbon::tresbon::thmbsp::thmbsp::thmbsp::thmbsp:

These guys bypassed it, that would also be fine for me as balance control has no use to me

http://www.hifi-forum.de/viewthread-185-9804.html


http://bilder.hifi-forum.de/medium/598982/uberbruckung-des-balance-regler-im-kenwood-basic-c2_255808.jpg

http://img825.imageshack.us/img825/9941/finale001255882.jpg

Kurzschluss= resistor
Widerstand= short circuit


They used 2 180kohm resistors.. I went back and forth as a lot of values were thrown out and poor google translation made it confusing, but then I looked at the color bands (Hey look at me, I'm learnin') they are in fact 180k ohm resistors with 1% tolerance. I don't know why they need resistors as I don't know much about electronics. I assume the short is there to bypass the balance control and the resistor is there to effectively remove the operation of the varying degrees of loudness which would be controlled by the dial? This is an assumption and probably incorrect. Is there a reason to add a resistor or would breaking the circuit by removing the solder connections be enough? I don't know, so I'll just follow what these guys did.

I have to desolder entirely the pot and remove it. Then I have to find somewhere that sells 180k ohm resistors.

matteos
03-25-2013, 04:31 PM
Radioshack rather unhelpfully doesn't sell 180k ohm resistors. But they do sell, 100k ohm, 47k ohm and 33k ohm. So I bought a pack of each as their value adds up to 180k ohm and it is my understanding that I can wire one of each together by twisting the end together and then soldering it. The wattage value of the resistors is 1/2 watt. I'm not sure what wattage I needed so I went with the highest ones I could buy since it doesn't matter if I have more but it matters if I have less.

Before I get round to doing this this evening, it would be really helpful if someone could chime in if I'm making some glaring schoolboy error.
Cheers.

matteos
03-25-2013, 04:31 PM
dupe, sorry

matteos
03-25-2013, 07:21 PM
Here's a shot of the guts

http://img687.imageshack.us/img687/903/67674914.jpg

no real reason...

And this is the little bleeder that causes all the problems...

http://img28.imageshack.us/img28/6758/15993811.jpg

matteos
03-25-2013, 10:48 PM
Success!! I'm actually surprised.

Remove solder and pot
http://img202.imageshack.us/img202/4982/pot1m.jpg
http://img560.imageshack.us/img560/7845/pot2.jpg

Put resistors in series, by wrapping wire then covering joins in solder. I trimmed a bit off the wire on both ends on the middle resistor to make this easier. It doesn't matter which order or which way around you put the resistors.

http://img197.imageshack.us/img197/2815/resistor1.jpeg

most nerve wracking part, short the two joins and attach resistors without buggering up separation of each other

http://img694.imageshack.us/img694/9330/resistor.jpg

Here's a thought, just get an actual 180k ohm resistor off the web, having three gives you little room to fit stuff back in.

Hope this helps anyone with similar problems, two solutions, repair pot, failing that bypass.

Now I'm going to have that beer, connect up my record player and see what all the fuss is about with this c2 phono stage.

:thmbsp::music::beer::beerchug:

matteos
03-25-2013, 11:50 PM
Biig panic moment. connected everything up, huge hum out of both speakers, looked at the ground wire fropm TT it was starting to come apart. Good thing I had my soldering stuff out, soldered it back together. plug it all back in. huge hum still. More panic... Figured out my rca cable was screwed up, all is well, now I'm tired.

matteos
03-26-2013, 01:14 AM
Everything is working great except the phono section, when I plug it ion there's a huge hum, I was getting it off every input till I switched out my rca cable, but it's really bad on the phono still, dead silent on everything else, do you think the phono section is screwed or my ground wire is.

OTOH I see why people go for separates, playing music from my phone with its crappy DAC is a noticeable improvement even against my Denons good DAC

matteos
03-26-2013, 02:09 AM
This is a real good preamp, I hope I can fix my phono problems, but this one is a keeper, everything sounds better through this and I'm talking 256kbps mp3 on a crappy phone DAC vs FLAC on a great Burr Brown DAC. Even if I can't figure out the phono section. This is staying on my deck, I only paid $35 for it (it was broken)

Very happy despite problems. :)

matteos
03-26-2013, 10:16 PM
Well after unplugging everything, switching things around grounding the ground to my receiver, grounding it back to the pre-amp.... I wiggled the ground wire and the hum went away. LOL

Anyway, I wanted to make a final post just to say how great this pre-amp is!!

The phono stage is much better than the one on my Denon 3803, the highs and mids are clearer, but what is best is that the bass is so well defined now. Listening to Flea on the new Atoms for Peace. Superb.

If you get a chance to pick one of these up for nothing because "one channel is out". Do it, while the fix isn't easy, you can do it if I can do it and this preamp really is a good one.

purenrg
04-03-2013, 09:55 AM
Sorry Matteos, just getting back to my thread, sounds like you had a little trouble?
It was a bitch that was for sure! Can you re-post those last pics, they seem to be missing? Thanks.

matteos
04-03-2013, 02:17 PM
Yeah, no worries. I did have trouble, sadly it was at the very end of fiddling around with that pot, wish I'd broken it at the start and not the end!!

I deoxited the whole thing the other day and all my other troubles are gone (intermittent crackles, one channel dropping out after a couple of hours of play).

matteos
04-04-2013, 01:59 AM
I know I'm basically talking to myself in this thread... But my preamp is getting kind of hot when I leave it running.. much hotter than my amp.. is this normal?

amb426amb1
04-04-2013, 08:21 AM
Not an expert in this area but just went thru adjusting my Sansui integrated and brought everything back into specs and it is running noticeably cooler. The bias had shifted up. I also have the C2 pre with a bad balance pot. I'm going for the bi-pass fix. I don't recall it ever running very warm. I'll try to get it out of storage fix the balance and play it to test how warm it gets.

purenrg
04-04-2013, 08:24 AM
Yea, I know what you mean, not much interest in this topic from others I ?
My C2 doesn't seem to be getting that warm.

amb426amb1
04-04-2013, 12:59 PM
Ok I did the balance fix this morning and ran the unit for about 3 hours straight. It did not get very warm at all. If you feel that much heat i would start checking things out.

matteos
04-06-2013, 01:38 AM
It's not getting warm anymore, maybe the deoxit soaked in and did some wonders, I don't know... It's a little temperamental but it's still good. Thanks for the feedback fellas.

EchoWars
04-06-2013, 08:17 PM
http://img694.imageshack.us/img694/9330/resistor.jpg
Good Lord! You're joking, right? You live in LA, and can't track down a proper resistor?

matteos
04-16-2013, 03:58 PM
http://img694.imageshack.us/img694/9330/resistor.jpg
Good Lord! You're joking, right? You live in LA, and can't track down a proper resistor?

Nope. I couldn't, not in Rat shack, not in Frys, not anywhere close to me, I went in about 5 different stores... I could have got one off the web but I figured this would work and it did. Not pretty though, if you're not impatient like me order one off the web.

petehall347
04-16-2013, 04:15 PM
just a thought if you get the correct resistors mount them on top of the board for a neater job .
failing that put a new balance pot in there .:D
or even leave the old pot in place and add the shorts .:scratch2:

matteos
04-16-2013, 05:12 PM
The old pot is destroyed, I tried to repair it but I snapped the fiberglass contact. There is no replacement pot available. :(

Yeah it looks like crap on the circuitboard, but it is out of sight and out of mind. Unless it breaks I'm just going to leave it.

steveeboy
04-24-2013, 09:30 AM
can anybody explain why the resistors are needed? I bypassed mine with 2 jumpers as described in some of the other threads and it works fine.

Looks like so, the two jumpers at VR-1 on the board:
https://twitter.com/realsteveeboy/status/327051242851426305/photo/1

When I removed the balance pot, I tested it with a DMM and found that in the center position the resistance was "0" anyway. At each end(right or left) the resistance was exactly the same, but cannot recall the value right now. but 99.9% sure it wasn't 180k ohm or anything.)

This is because my pot was actually NOT not bad at all, NOT the problem. My issue with the channel going out turned out to be the tape/source monitor switch. I cleaned that out more thoroughly and now the unit seems to work fine with the bypass installed and no pot in place. Some of the other threads on the C2 note that before you do anything, you need to check that switch and clean it out real well.

DUH!

Yes, I am a dumb ass. Should have tested first, de-soldered later! Would have saved some hassles for sure.

So, back to the original question, are the 180k ohm resistors necessary?

If so, why?

I will probably re-install the pot when I get a chance, but kind of sick or working on it right now and just want to enjoy the unit for a while.

Another fix I had to perform was on two of the source inputs (tuner and aux 1). Back in college I lived in a house with some really sketchy knob and tube wiring. On two occasions I blew out inputs when I attempted to plug in some PA outputs to my C2 when those items were plugged into a different outlet. Heard a lour POP! Saw an arc at the RCA jack, and then the input went dead.

As part of this general attempt to fix the C2 I finally disassembled the boards, flipped them over, and found these two burnt traces for aux 1 and tuner inputs:
https://twitter.com/realsteveeboy/status/327053337142890496/photo/1

This thing is very easy to work on, even for a noob like me, so I figured I could jumper that real easily. I think the euro units have a couple of caps on the inputs which are not present on my universal unit, so I de-soldered the filled holes for those caps for each input... Like so (note open holes):
https://twitter.com/realsteveeboy/status/327054530690809856/photo/1

Then I realized at this point I was going to jump to a pad feeding another jumper, so I could just go all the way to that jumper's end point near the switch. So, I removed J46 and J48 and went from that empty input cap pad to the removed jumper pads. Like so:
https://twitter.com/realsteveeboy/status/327055154807451648/photo/1

So, the fiasco of removing and jumpering the still working balance pot was at least a bit tempered by the fact that now my aux 1 and tuner inputs work for the first time since @1993.

I really appreciate all the info and expertise on here, it's a great help to those dumb enough to crack these units open and attempt repairs.

matteos
04-24-2013, 06:26 PM
I got the info off that German website, as to why a resistor is needed I'm afraid I could only guess.

opa1
04-24-2013, 08:15 PM
I did the simple jump on mine. No resistors. Works perfect. Left the pot in place too.

MK

dannomite123
04-29-2013, 04:31 AM
Hey all. New to the forum and glad to see its full of so many knowledgeable folks.

My problem started off the same. Dodgy balance pot. It was quite scratchy to operate and sometimes you would get a terrible distorted sound out of the blue.

I sprayed it with Deoxit to no avail. So I pulled it apart and noticed no real contamination or oxidization. I pulled the swipers out a bit thinking they had lost tension and were not making good contact with the rings. What I didnt notice was the left channel swiper had come away from the plastic, broken rivets.

I placed it back it and powered up the unit and noticed the left channel was completely dead. I pulled the balance pot apart again this time noticing the left channel swiper completely detached from the plastic. I glued it back on, reassembled and checked with multimeter. It all checked fine. Soldered it back in but still no left channel.

I hooked my oscilloscope(limited experience with this...) with a 500Hz sine wave from the function generator. Probing from the input jacks from inside the C2 I found the right channel was spot on but the left channel was only displaying a signal half the strength. I traced the left channel signal which displayed the same weakness to a 330 ohm resistor just before the balance pot and it died straight after the resistor. The resistor tested fine but I think its irrelevant as the signal was already weak.

I tried with all the inputs on the back with the same results. Weak left channel signal. I swapped the rca leads from the function generator with no luck and hooked the C2 to my power amp and speakers and left channel is definitely dead.

I know scopes are supposed to help you trace where a signal goes bad, but how do you do that when its already bad at the source? My only guess is that something got shorted when I reinstalled the balance pot the first time with the loose swiper.

I apologise for my long winded explanation in advance.

diepbtt
04-29-2013, 07:58 AM
Hey all. New to the forum and glad to see its full of so many knowledgeable folks.

My problem started off the same. Dodgy balance pot. It was quite scratchy to operate and sometimes you would get a terrible distorted sound out of the blue.

I sprayed it with Deoxit to no avail. So I pulled it apart and noticed no real contamination or oxidization. I pulled the swipers out a bit thinking they had lost tension and were not making good contact with the rings. What I didnt notice was the left channel swiper had come away from the plastic, broken rivets.

I placed it back it and powered up the unit and noticed the left channel was completely dead. I pulled the balance pot apart again this time noticing the left channel swiper completely detached from the plastic. I glued it back on, reassembled and checked with multimeter. It all checked fine. Soldered it back in but still no left channel.

I hooked my oscilloscope(limited experience with this...) with a 500Hz sine wave from the function generator. Probing from the input jacks from inside the C2 I found the right channel was spot on but the left channel was only displaying a signal half the strength. I traced the left channel signal which displayed the same weakness to a 330 ohm resistor just before the balance pot and it died straight after the resistor. The resistor tested fine but I think its irrelevant as the signal was already weak.

I tried with all the inputs on the back with the same results. Weak left channel signal. I swapped the rca leads from the function generator with no luck and hooked the C2 to my power amp and speakers and left channel is definitely dead.

I know scopes are supposed to help you trace where a signal goes bad, but how do you do that when its already bad at the source? My only guess is that something got shorted when I reinstalled the balance pot the first time with the loose swiper.

I apologise for my long winded explanation in advance.


I have a Kenwood pre amp C1 and one channel is always quieter as the other. So i must adjust the balance control to +2 so that it gets reasonable result though the good channel seem to be more clearly, strongerly (bass & treble).

Suspecting the balance volume should be the culpit i have sprayed CRC -2-26, severaltime but with no result.
Trying bypass with 2 resitors 180K as someone stated in a german website about but further no result.

As my last trial before i will bring it to a service center i try to relace the volume pot. (alps dual gang 100kaX2 but only with 3 legs) and the wonder both channels now absolutely equally.

So the culpit is the volume pot, not the balance in my KENWOOD C1.

Now i can use it without problem. Of course i must forget the loudness function because i can not find a alps dual gang 100Kx2 with 4 legs(4. leg is intended for loudness). but i can accept it since i never use loudness.

janikphoto
02-15-2014, 03:14 PM
So, does anyone have pics from those who just used jumpers? Is it done exactly the same as the resistors... just with jumper wire instead?

janikphoto
02-15-2014, 03:31 PM
OK, I jumped it, but now I get NO sound. I'm moving backwards here... I left the pot in. Do I need to remove it to make this work, or can I leave it and this bypass will work?

https://scontent-a.xx.fbcdn.net/hphotos-prn1/t1/1920506_10151970745722817_1369133759_n.jpg





*****UPDATE*****
So, I went back and snipped the jumpers, just to see if adding the resistors would make a difference. They are still there, just clipped in the middle and the mini solder jumps in place, too. I powered it up, just to see what would happen with them clipped and before the resistors went in. It plays now! Full stereo sound with no balance adjustment. So, at least I'm working now! Sound is superb through headphones, so I'm guessing you might not need the resistors, just do the solder jumps on their own.

EchoWars
02-15-2014, 04:04 PM
OK, I jumped it, but now I get NO sound. I'm moving backwards here... Well, you can't jumper them ALL together...one of those pads is ground. :)

janikphoto
02-15-2014, 04:34 PM
Well, you can't jumper them ALL together...one of those pads is ground. :)

So, the resistor is just there to go from positive to ground, and when I used a solid wire, it was shorting it. I'm guessing, anyway. Either way, it's working now!

derekva
02-17-2014, 03:12 AM
So, the resistor is just there to go from positive to ground, and when I used a solid wire, it was shorting it. I'm guessing, anyway. Either way, it's working now!

Correct. Glad it's fixed!

-D

derhussl
04-10-2014, 02:09 AM
thanks matteos for this post. I am about to pick up a C2 with a channel out problem so I am guessing I will be getting in to this and trying to fix or bypass this and get it working. This one will be coupled with a Kenwood KM-209 amp pushing some cerwin Vega VS-150 speakers.

This post really helped me out and gave me a way out if I cant fix that pot. This will be my first electronic project other then re doing my rca cable and ground on my TT. So let the headache begin!

janikphoto
04-14-2014, 05:40 PM
thanks matteos for this post. I am about to pick up a C2 with a channel out problem so I am guessing I will be getting in to this and trying to fix or bypass this and get it working. This one will be coupled with a Kenwood KM-209 amp pushing some cerwin Vega VS-150 speakers.

This post really helped me out and gave me a way out if I cant fix that pot. This will be my first electronic project other then re doing my rca cable and ground on my TT. So let the headache begin!

It's not the worst piece to work on. I just took mine apart a couple hours ago to fix what I'm guessing was cold solder joints on the rca outputs. I'm testing it now and it seems better.

derhussl
04-20-2014, 02:38 PM
hey guys I just picked up a c2 wit this same issue well I had it working the resistor way then decided to remove the switch and just jump it. Well know its will not work and I am actually thinking I messed up the circuit board when I de sodered a piece of the green line came off and now no matter what I do the unit is dead. Mad at myself for tinkering with it after I acutally had it going right. So here comes the question to you guys.

1. how can i tell if i messed up the board and are those green lines the circuit?

2. If the answer is yes and I messed it up is there another place to by pass this?

I dont care about the balance I just want it to work.

Thanks for any help. I am going to take it to a shop next week if you guys are stumped I am hoping you experienced guys can help me out.

Thanks in advance for any help at all. I am really excited to have this C2 but now I need to fix it or I guess break down and get it to an electronics repair place which will not be nearly as cool as doing it myself. I am a total noob to electronics and all that so just a heads up on that!

Thanks guys

derhussl
04-22-2014, 12:04 AM
well just to keep you updated i got the c2 working. I did mess up the circuit board a bit and had to bypass the balancer pot farther up. Worked like a charm just using some solder. So even if you mess up the board a bit around where the pot was its salvageable. Going to let her play for a while and enjoy.

janikphoto
04-22-2014, 01:54 AM
Be sure go resolder the joints at the RCA's, if you have sound cutting in and out issues, like mine did. After I did the balance mod, I started having issues, which I tracked to cold solder joints back there.

derhussl
04-22-2014, 03:58 PM
well its doing something odd it works fine and all of the sudden the right channel goes fuzzy and then its dead. Is that what you were experiencing or was your different. I tried switching in between sources and it stayed consistently down thru it all then it just came back miraculously. After a few hours it went down again now its back. Any ideas? I thought maybe id didn't solder that channel with enough solder maybe and when it heats up its not enough of a bridge?

Will definitely check the RCA solder joints thanks for the heads up on that. I think what I am describing is different from what you had going on correct? Mine isn't cutting in and out and its all isolated to the right channel?