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Kenwood KR-7600 buzzing

J

jalawtoo

New Member
When I turn on my Kenwood KR-7600 receiver, a buzzing sounds starts, and gradually gets louder. I am unable to play any music (regardless of source).

Video:

Anyone have any ideas on the source of the sound and/or if it can be fixed?

Receiver: KR-7600 | Kenwood

Speakers: RP-600M Bookshelf Speakers | Klipsch

Phono 1: KD-2055 record player | Kenwood

AUX: Daisy chain
  • RCA cable...
  • ... to DragonFly Black v1.5 DAC | Audioquest...
  • ...to USB to Thunderbolt adaptor | Apple...
  • ... iPad | Apple

Sentimental value: This belonged to my dad. It was my favorite thing he owned, and after he passed, I got it. Hoping it can be fixed!
 
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Are you familliar with it? did it start doing this suddenly?. Sounds like a 60HZ hum. The sound inject pot, looks like it's on?. Take a look at the wiring (the input cables), all fully pushed-in their jacks?.
 
Sounds like the speaker protection relay is buzzing, most likely due to a weak relay driver transistor. I did not hear the relay click - the relay is on the left side of the receiver
 
turboyam - Sort of familiar with the unit, but very new to audio in general. To me it sounded like a 120 hz hum, but I could be wrong. The sound inject nob is pulled out, so assuming that it's off. All cables are fully pushed in. The buzz is coming from the Kenwood, not the speakers. No music plays through it since the buzzing started.

gort69 - Is this a manageable fix?

This all started on Monday. I was playing music from the iPad, and everything was fine. Then I left, turning off the iPad/music, but forgetting to turn off the Kenwood. When I returned, it was buzzing very loudly, and here we are.
 
Faulty relay driver is an educated guess.

The beauty of these old things is that for the most part they are repairable. If you don't have experience desoldering and soldering I'd recommend having it repaired by a tech
 
Pretty sure Gort is right, i should stay in my paperclip malfonction diagnostic job:beatnik:. The sound inject knob tho, if pulled out, turns on that fonction. If you crank-up that sound inject volume, the music's volume is going to go down but, this has nothing to do with your problem, just push in that S.I. if not in use.
Try to fix, or have a tech. fix your 7600, i have it's lil bro, the KR-6600 looove it!.
 
Thanks for the tip. Just pushed the sound inject in. Going to attempt to fix it this week. I'll keep you both updated on my progress. Thanks for the insight here!
 
Do you have a multi-meter? There are a few basic voltage checks you should do before replacing any parts to ensure that you're on the right track
 
Hopefully you have mini-grabber leads for it. If not tape your probe leads so that just the very tip is exposed.

Remove the top cover, the left side fake heatsink and the left inner metal side cover.

For all measurements you will be testing for DC voltage so set you meter for that

The first set will be on the power supply "A" board X00-1770-10. This is at the front right corner.

Disconnect the speakers and power it up If it is in fact the relay buzzing it should be pretty obvious.

With the black lead to the metal chassis, Check the following wire wrap pins

#1 (+52VDC)
#6 (-52VDC)
#2 (+23VDC)
#5 (-23VDC)
#3 (+13.8VDC)

Next is the power supply "C" board X00-1790-10. This is the verical board on the left side that has the relay on it

Black lead to chassis again

#6 (0VDC)
#9 (0VDC)

On these last two you'll probably see something like 20-50mvDC, but that's OK

Post your results
 
gort69 said:
Hopefully you have mini-grabber leads for it. If not tape your probe leads so that just the very tip is exposed.

Remove the top cover, the left side fake heatsink and the left inner metal side cover.

For all measurements you will be testing for DC voltage so set you meter for that

The first set will be on the power supply "A" board X00-1770-10. This is at the front right corner.

Disconnect the speakers and power it up If it is in fact the relay buzzing it should be pretty obvious.

With the black lead to the metal chassis, Check the following wire wrap pins

#1 (+52VDC)
#6 (-52VDC)
#2 (+23VDC)
#5 (-23VDC)
#3 (+13.8VDC)

Next is the power supply "C" board X00-1790-10. This is the verical board on the left side that has the relay on it

Black lead to chassis again

#6 (0VDC)
#9 (0VDC)

On these last two you'll probably see something like 20-50mvDC, but that's OK

Post your results
Click to expand...
Gort69, Can I jump in ? I have the same problem with my Kenwood KR 7600 ,and took the test on my pins (A) board,

Pin1 +51.6
Pin6 -51.8
Pin2. +23.8
Pin5. -36.3
Pin3 +14.4
Pin5. Is way off and Pin3 is off.
Haven't got to Pin6 and Pin9 of C board get .hope you're still available
 
jalawtoo said:
When I turn on my Kenwood KR-7600 receiver, a buzzing sounds starts, and gradually gets louder. I am unable to play any music (regardless of source).

Video:

Anyone have any ideas on the source of the sound and/or if it can be fixed?

Receiver: KR-7600 | Kenwood

Speakers: RP-600M Bookshelf Speakers | Klipsch

Phono 1: KD-2055 record player | Kenwood

AUX: Daisy chain
  • RCA cable...
  • ... to DragonFly Black v1.5 DAC | Audioquest...
  • ...to USB to Thunderbolt adaptor | Apple...
  • ... iPad | Apple

Sentimental value: This belonged to my dad. It was my favorite thing he owned, and after he passed, I got it. Hoping it can be fixed!
Click to expand...
This Kenwood receiver is quite old. It needs to be serviced. It could be a lot of things. Bad solder joint, bad capacitors or even a bad ground. I would have someone competent to take a look at it. Be sure to do your research before taking it to anyone. So many bad shops that will ruin it and charge you for it. Its a heirloom and needs to be restored. When you look at it it will bring back good memories of dad.
 
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