Login|Contact Us
Question and Answer

Consumer Electronics

Ask a Consumer Electronics Question, Get an Answer ASAP!

  • Ask A Question
  • Browse Answers
  • Meet The Experts
  • How JustAnswer Works

I recently purchased a vintage Kenwood KA-7100. It works fine

 
Rod's Avatar
  • Answered by:Rod
  • Systems Engineer
  • Positive Feedback: 98.2 %
  • Accepted Answers: 1315
Verified Expert
in Consumer Electronics

Recent Feedback

Positive
I aCCEPT AND APPRECIATE rOD'S OPINION AND ADVICE. aS i SAID ABOVE HE GAVE ME...
Positive
So far so good. We have not got the problem solved yet. I will tip him when we...
Positive
I am an electronic engineer by training. Never designed PS with floating...
Positive
Thanks! I ordered it from eBay.
Positive
Straight forward and instant response.
Positive
Thanks Rod, I know not to buy another Samsung
Positive
Thank you for a very prompt answer with the necessary manuals.
Positive
Fast and helpful answer...Thanks
Positive
i appreciate the download for the owner's manual. this will be a big help when...
Positive
Rod lead me to the answer I originally thought. That the equipment was defective...

Customer Question

I recently purchased a vintage Kenwood KA-7100. It works fine except the right channel distorts and crackles. Why is this?

Submitted: 1507 days and 2 hours ago.
Category: Consumer Electronics
Value: $9
Status: CLOSED
Picture
Expert:  Rod replied 1507 days and 2 hours ago.

Hi Tony,

Does it do this when changing the volume or channel balance (left - right). Meaning to you hear the crackling more or less in the right channel?

Thanks,
Rod

Customer replied 1507 days and 2 hours ago.

No. It distorts and crackles Consistantly from the right channel only, not just when the knobs are turned. It almost sounds like the speaker is blown, although I switched the speakers and still crackles from the right only. Negating the possibility that it's the speaker. I then rewired the speaker to the "speaker B" position and the problem continued. The left speaker sounds perfect.

Picture
Expert:  Benimur replied 1507 days and 2 hours ago.

Hi and welcome to JustAnswer,

The Kenwood KA-711 is a 1977 model. Based on the age of the amplifier, most likely cuplrits would be coupling capacitors specifically in the pre-amp/tone control circuits. Additionally, these year designs uses carbon type volume controls and tone controls which are prone to dead spots, crackling and noise due to age.

Corrective measure for the controls would of course be replacement. Temporary workaround would be to spray the wiper/inside with electonic contact cleaner. The capacitors on the other hand does not have a temporary remedy, they must be replaced. Diagnosis and determining which would require a scope for visual check of no input signal level at the input/output end of the coupling capacitor. Another method would be shotgun approach, replace all of the signal capacitors. This of course would require familiarity with electronic components & circuitry, use of a DVM and a soldering iron. It would be to your added advantage access to a service manual or at the very least a schematic diagram.

Hope this be of initial help/idea. Good luck and thank you for using JustAnswer.

Should the above address your concern, please take a moment to click on the green ACCEPT THE ANSWER button. Appreciate it in advance.

Customer replied 1507 days and 2 hours ago.

I have no electronic experience. Should I even bother trying to fix it myself?

Picture
Expert:  Rod replied 1507 days and 2 hours ago.

Hi Tony,

You could have leaking coupling capacitors, or near failing (read noisy) power output transistors for the right channel. However, the first thing I try in these type of units is to clean the switches and potentiometers. I think, in your case it may just be the switches that need cleaning. This unit is easy to work on. You just need to remove the top and bottom cover to get to the switches. DeoxIT is the best solution for cleaning the switches which you can obtain here. I don't think Radio Shack carries this, but you can check. I recommend the small bottle (around $15). Use the brush that comes with the bottle and like painting, slide it along the edge of the bottle to remove excess. Then touch the brush to the switch areas and contacts and then move the switches back and forth. Do all of the switches - its good preventative measure.

I've had a lot of success in solving noise from older units with this. If you still have the problem, then the right channel electronics will need to be diagnosed. I could be a simple coupling capacitor, but you will need a schematic and electronic experience. The parts for this can still be obtained, and its a good unit to hang onto.

Thanks,
Rod

Accepted Answer

Picture
Expert:  Rod replied 1507 days and 2 hours ago.

Hi Tony,

You do not really need any electronic experience to clean the switches. Just disconnect the power when you remove the covers. What the unit looks like on the inside is available here. Just be gentle with the q-tips, all you are really doing with them is absorbing any excess cleaning liquid. The liquid, and the action of moving the switches back and forth will do the cleaning.

Thanks,
Rod

Expert TypeSystems Engineer
Category: Consumer Electronics
Pos. Feedback: 98.2 %
Accepts: 1315
Answered: 2/26/2009

Experience: FCC Commercial Licenses, BSCS, ASEET, 40+years Electronics & Communication Systems

Ask this Expert a Question >
 
Tweet

5 Electronics Technicians are Online Right Now

Ask Your Question Now
Ask an Electronics Technician
Type Your Consumer Electronics Question Here...
characters left:

Top Consumer Electronics Experts

See More Electronics Technicians

In The News

Nbc
Washington Post
New York Times
Cnn
Learn More

How It Works

  • Ask an Expert
  • Get a Professional Answer
  • Ask Followup Questions
  • 100% Satisfaction Guarantee
Learn More
close
Find Expert answers related to your question.
Sign up using email
We will never post anything without your permission.
Already have an account? Sign in

Ask an Electronics Technician

Get a Professional Answer. 100% Satisfaction Guaranteed.
180 Electronics Technicians are Online Now
Type Your Consumer Electronics Question Here...
characters left:
Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.
Truste
Contact Us | Terms of Service | Privacy & Security | About Us
© 2003-2013 JustAnswer LLC