Jump to content

Harman Kardon 330B - volume control erratic behavior


januacoeli

Recommended Posts

Hello,

 

 

For many years I had wanted to get myself a nice hifi system and start listening to vinyl records, so finally this year I decided to take action and after some research and many questions asked to people around me that are into the subject, I have composed the following setup: 

- Technics SL-1200 MK2 (circa 1995 production)

- Harman Kardon 330b

- Tannoy Platinum B6

 

Only the speakers were bought new, while the turntable and amplifier are second hand.

I have started listening to records last September and was very happy with the quality and warmth of the sound, but since one month now the HK is behaving rather oddly, namely the volume control knob. The volume actually seems to jump randomly all the time and it sounds like if a lot of static were accumulating all over the place and messing up with the sound.

After having carefully opened the amplifier to do a visual check, everything seems rather normal - even though I am new to all this ! - and there was no trace of dust or strange stuff lying around, so I did not even tried cleaning it. I have also plucked the knobs out and did some light cleaning, but only the usual dust was to be found. I cannot properly verify behind the volume knob inside, as is bellow the sort of metal box containing the radio station meter.

I am sure the problem somehow comes from the amplifier, as in the first months I had listened to a couple of records that I know very well and these were playing perfectly. The turntable was sold to me by a producer and we tested everything before buying, so I have no doubt about it.

At this point I have plugged out / plugged all the connections (speakers and RCA cables) several times and nothing seems to change.

 

The HK actually belonged to the husband of the lady who sold it to me, as she was getting rid of all his stuff after he died a couple of years ago. Although I have tested it at her place before buying and everything sounded fine, she has no knowledge of this stuff and she even offered me a couple of her vinyl records, so I have decided not to reach to her for the moment and try to solve the problem on my own, also because I bought for a rather cheap price.

So before I get rid of it or give it to someone who will repair it, I would like to explore further and would love to have your help.

Has anyone here had this same problem? Is it common amongst analog amplifiers generally or rather specific to this model?

 

Anyway I appreciate all the information and help and I can provide all the details / photos required.

 

Thank you in advance : )

 

  • Like 1
Link to comment
Share on other sites

2 hours ago, billybob said:

Welcome to the forum!

Deoxidizing control knobs , especially in your case may likely correct the volume control.

Look at YouTube or read about contact cleaners like Deoxit or CRC.

People do this all the time and there is a procedure.

Thanks!

 

@januacoeli


Hello,

 

Appreciate the welcoming words!

Thanks for the tip. I was wondering this might probably be a beginners thing.

 

But what struck me is the way sound changes. I mean, it is not just like the volume level oscillates randomly, but sound also gets distorted, as well as the definition overall. Is it normal?

And on a related note, does the same logic apply to other knobs, such as bass or treble? I mean, can they also affect sound similarly and should be deoxidized as well?

 

Thanks once more

  • Like 1
Link to comment
Share on other sites

4 minutes ago, januacoeli said:


Hello,

 

Appreciate the welcoming words!

Thanks for the tip. I was wondering this might probably be a beginners thing.

 

But what struck me is the way sound changes. I mean, it is not just like the volume level oscillates randomly, but sound also gets distorted, as well as the definition overall. Is it normal?

And on a related note, does the same logic apply to other knobs, such as bass or treble? I mean, can they also affect sound similarly and should be deoxidized as well?

 

Thanks once more

Yes do that, but do the volume first.

Besides online do a general search of the forum here using the keyword Deoxit.

Just the volume control should work wonders. This is well known roundabout. Mostly needed on older vintage equipment, but is not sacred.

  • Like 2
Link to comment
Share on other sites

47 minutes ago, billybob said:

Yes do that, but do the volume first.

Besides online do a general search of the forum here using the keyword Deoxit.

Just the volume control should work wonders. This is well known roundabout. Mostly needed on older vintage equipment, but is not sacred.


Will give it a try. Thank you

  • Like 1
Link to comment
Share on other sites

Quick reply to give some feedback.

Just gave the volume knob a spray of deoxit fader - the only product of this brand I have found in Switzerland; wc-40 seems to be king in here - and the difference is huge.

No more erratic behaviour or weird static sound when changing the volume. I just have the feeling that I now have to turn more rightwards to have more volume compared to before, even though this was already happening before deoxit and I am not 100% sure.

I have also sprayed a little bit of the function knob (fm, am, phono, etc) and also notice some difference. Hopefully I did not do a silly thing with this knob but I have figured the logic must be the same.

Would you advice also applying dioxit on the balance, treble and bass knobs, even though there is nothing strange about them and they are less used?

 

  • Like 4
Link to comment
Share on other sites

Over time the carbon disks (potentiometers sp) get some dirt, smoke, oxidation etc on them

 

and this effects their resistance and creates noise as the wiper travels over the impurities.

 

Electrical contact cleaner washes the grit off, CRC is good and affordable, Deoxit seems to be the king of these products, it has worked well for me.

 

Put some paper towel or good quality rag around the area you are cleaning to absorb the over spray and mess coming out, then repeat 24 hours later.

 

While you have the lid off, blow the unit out with compressed air, and use a magnifier to examine the solder joints, also check the boards for electrolytic capacitor leaks and hot spots.

 

You and also check the transistors to see if any are running hot, without electrocuting yourself. If you have a friend that works on electrical equipment of any kind they can help you.

 

If the unit is approaching 30 years old, and you love it, get some quotes to replace all of the electrolytic capacitors before one fails and burns a path across your transistors and other components. Usually in the $200-300 range to replace all inc the filter caps with top quality panasonics, nicicon etc. Also have the relay switch-s replaced, they pit and fail over time.

 

 

Link to comment
Share on other sites

1 hour ago, januacoeli said:

Would you advice also applying dioxit on the balance, treble and bass knobs, even though there is nothing strange about them and they are less used?

 

Yes clean all of the carbon disks thoroughly, you will be glad you did.

 

If you love your unit, and see another for sale that is working at a low price, you may want to keep it in a closet as a future organ donor

  • Like 1
Link to comment
Share on other sites

I have a Marantz 3600 preamp that was restored a few years ago and recently one channel went out and then the other. They both briefly had intermittent noise then went completely dead in a matter of minutes.

I'm no tech but definitely thought something had taken a dump. My tech (not the one who originally restored this preamp) told me to deoxit all the knobs and switches and to work them extensively.

So that's what I did and everything came back to life. Really surprising to me that dirty switches and knobs could have that kind of effect and be fixed this easily.

Sent from my SM-G950U using Tapatalk

  • Like 2
Link to comment
Share on other sites

2 hours ago, januacoeli said:

Quick reply to give some feedback.

Just gave the volume knob a spray of deoxit fader - the only product of this brand I have found in Switzerland; wc-40 seems to be king in here - and the difference is huge.

No more erratic behaviour or weird static sound when changing the volume. I just have the feeling that I now have to turn more rightwards to have more volume compared to before, even though this was already happening before deoxit and I am not 100% sure.

I have also sprayed a little bit of the function knob (fm, am, phono, etc) and also notice some difference. Hopefully I did not do a silly thing with this knob but I have figured the logic must be the same.

Would you advice also applying dioxit on the balance, treble and bass knobs, even though there is nothing strange about them and they are less used?

 

We like feedback and working the controls that you Deoxit is key. Happy you were able to find it. I usually stop when problem solved but, yes. Come back again...

Link to comment
Share on other sites

Late to the party, but for years I resisted using Deoxit because I figured it was all hype.  I'd replace volume and tone pots without a second thought.  A couple weeks ago I found a Yamaha amp in someone's trash and brought it home to find it had a scratchy pots (bass, treble, loudness, and balance) that would also cut out.  All the normal sources (Digikey/Mouser/Soniccraft/Parts-Connextion/Parts-Express) had nothing in stock for the balance pot and I didn't feel like ordering a single pot that had a 20 week lead time for a free amp so I picked up some Deoxit, gave each of the pots a spray, a working, then another quick spray.

 

WOW.  Amazed how well that worked.  I can't imagine how much money and time I would have saved had I started using it years ago.

 

Glad it worked for you.

  • Like 2
Link to comment
Share on other sites

On 12/20/2020 at 4:18 PM, Bubo said:

 You and also check the transistors to see if any are running hot, without electrocuting yourself. If you have a friend that works on electrical equipment of any kind they can help you.

 

If the unit is approaching 30 years old, and you love it, get some quotes to replace all of the electrolytic capacitors before one fails and burns a path across your transistors and other components. Usually in the $200-300 range to replace all inc the filter caps with top quality panasonics, nicicon etc. Also have the relay switch-s replaced, they pit and fail over time.

 

 


So far so good, no overheating or other signs. But of course I might be ignoring certain signs, since I am fairly new to all this. It seems to me that the previous owner of this HK unit was careful enough. 
 

On 12/20/2020 at 4:31 PM, Bubo said:

Yes clean all of the carbon disks thoroughly, you will be glad you did.

 

If you love your unit, and see another for sale that is working at a low price, you may want to keep it in a closet as a future organ donor


Actually this was the first amplifier I went to see for myself before buying and I have immediately fallen for it. Being an architect and very picky about design I feel everything is well balanced with this model and the finishings are of great quality. Sort of timeless design really. Also it does precisely what  I was looking for, no more, no less.

 

On 12/20/2020 at 5:09 PM, SWL said:

So that's what I did and everything came back to life. Really surprising to me that dirty switches and knobs could have that kind of effect and be fixed this easily.
 


Kind of the same for me. This was actually the last thing that came through my mind. At first I was convinced (and sort of afraid) that it was something to do with the turntable, namely the needle.

I am relieved now to find out that it is so much more simple than that.

 

On 12/20/2020 at 5:30 PM, billybob said:

 Happy you were able to find it. I usually stop when problem solved but, yes. Come back again...

 

Thank you for all the help and tips.

I guess I came to stay. Afterall there is plenty to learn and I am just starting.

Feels magical to rediscover all the records I have been listening for years on my sony mp3 player (which is quite good).

It’s like I had been hanging around people I actually did not know...

  • Thanks 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...