Harman Kardon 330C loud pop

vintage63

New Member
Hello all,

first time poster here but longtime lurker. Appreciate the vast knowledge here..
I have come across a Harman Kardon 330 C in nearly mint condition which plays fine but bothers me with a loud pop when a source like my turntable is started or stops . I have an old Elac 22 H turntable with auto return. Now i know that to start the receiver I leave the speakers disengaged and power them on later ...but it´s annoying to run to the receiver at the end of a record to turn off the volume or the speakers....and one doesn´t always thinks about it...Anyone with an idea how to fix that problem ?
Thanks in advance
 
Is the same receiver also susceptible to other electrical noise? Stuff like a washing machine cycling? You could also do the hair-dryer test...plug a hair dryer into the same circuit, and turn it on and off multiple times with the volume set to where it would be for normal listening levels.. Is the noise only when on phono, or does it also happen on a high level input? When on phono, does the noise happen with the hair-dryer even if the phono cables are disconnected? The answers can be hints about the path and source of the noise.

Do you have another receiver to swap in for connection to the phono to see if it's a phono issue or a receiver issue? There is often a capacitor across the switch contacts in a phono...if it's fried/open, then there would be no spark quenching when the phono turns off, and that can make all the problems you report.
 
Thanks for the answer. It also happens with the CD Player at the AUX input. So I think it is not specifically the phono stage
 
does it happen with the volume down? That tells us a bit more about how it's getting into the receiver. It still may be that the cap across the switch contacts (or an X-cap across the AC line) of the turntable is open, and repairing that might be the quickest answer.
 
so now we ask...radiated or conducted (thru the power line)? Here's a test...
Is there a nearby outlet on a different circuit breaker than the stereo? If so, you could plug the turntable and the receiver into different outlets on different breakers. If the problem gets a lot better, then the problem is conducted. If the problem doesn't really change, then it's probably radiated.
 
I have connected the receiver to a different outlet than the turntable and it makes absolutely no difference....the loud pop remains
 
does the noise persist with the turntable powered on the long cord and the input cables removed, with the 330 on a high level source?
 
I´m not sure if I can follow you here....I disconnected the turntable and the loud pops remain when CD into AUX is engaged
 
so, it's starting to seem like radiated emissions from the power on/off in the turntable motor and line cord. One way we could verify...if we leave the turntable plugged in to the outlet in the far-away room, and move the turntable to the far-away room, and the problem diminishes greatly, then it is radiated emissions. If it doesn't really change, then it's conducted emissions. Why is this important? It tells us more about the next step. I'm guessing this seems a little strange, but that's largely due to the remote nature of the trouble-shooting.
 
I will give it a try tomorrow..getting late here in Germany....I thank you kindly for your help up until now and I´ll report back sometime tomorrow..
 
Vintage, take the cover off and deoxit the selector switch, let dry for an hour and plug in and try again. I'd also recommend downloading the service manual (its free) from Hifiengine.com and seeing what other components are in the selector path.
 
A quick update: I have, of course, cleaned switches and push buttons -- multiple times just in case...
I have a second HK 330 C in not so good condition like the other one , so i swapped the units- and the loud popping sound occured there too.
Next thing I did was swapping the turntable, replacing the Elac with a Dual 1019 and the popping sound was much lesser loud, but it was still there.
Then I connected the CD player with my second audio system ( Sansui Six ) and although the volume knob from my Harman Kardon was turned to zero I got - guess what - a popping sound although it was not at all connected with it. So I guess it has something to do with the electric circuit.....and I have no clue how to fix that.
I´m counting on the experts here.

Cheers
 
Sounds like Djoffe was spot on. I'd hire an electrician to come and test your electrical in that room and maybe the house (not sure if you've tried the equipment in a different part of the house). Could be a safety issue.
 
Hmm..thanks for your answer. How come that my Sansui Six doesn´t make these sounds then. Has it maybe something to do that the HK 330C has no speaker relay?
 
I've got a Harman Kardon 730 at work with me. I have it on a surge protector. However, if I plug into the AUX In from my computer which is not on a surge protector, I will occasionally get a pop when certain machinery kicks on here at work.
 
A quick update: I have, of course, cleaned switches and push buttons -- multiple times just in case...
I have a second HK 330 C in not so good condition like the other one , so i swapped the units- and the loud popping sound occured there too.
Next thing I did was swapping the turntable, replacing the Elac with a Dual 1019 and the popping sound was much lesser loud, but it was still there.
Then I connected the CD player with my second audio system ( Sansui Six ) and although the volume knob from my Harman Kardon was turned to zero I got - guess what - a popping sound although it was not at all connected with it. So I guess it has something to do with the electric circuit.....and I have no clue how to fix that.
I´m counting on the experts here.

Cheers
See my post above. In addition, I would consider putting everything on a surge protector if you don't already. I use a POWERSQUID which protects not only against power surges but also lulls in the power supply.
 
Everything of my audio and computer related stuff is connected to surge protected sockets....Have to look into the socalled Powersquid like Ethan suggested maybe
 
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