BAD phono pops/crackles with HK 330C

Lunchbox2012

New Member
Hey all! Having some bad, really bad popping and crackling with the phono channel only on an HK 330C. Bought it in decent condition a few years back, had some scratchy pots so I had it cleaned up at Audio Lab in Harvard Square. It's sounded amazing since. Until....

These pops, they are INSANELY loud, while simultaneously it seems like I've lost a significant amount of volume from the turntable itself.

Pops continue even when there are no cables plugged into the phono inputs.

No buzz or hum, really.

Any clues what I might be dealing with before I just give up and bring it back to Audio Lab?
 
Are you getting any pops when TAPE or AUX is selected? Are the pops in both channels?
 
Transistors on the equalizer board.If its phono only.
Left channel Q102/104
Right channel Q101/103
 
Ah, lo siento! Running around at work.

The tape channel has hum, but no pops. The aux channel is clean, sounds amazing with an iPhone but incredibly low volume with my turntable, so unfortunately it's a lousy alternative to the phono channel.
 
Oh most definitely pops on both channels.

Amazing, I'll take a look at the specs when I get home and mess with those guys. Thank you!
 
If there are any tantalum caps on the EQ board they can cause pops as well. I'd recap the EQ board and replace all four transistors.:thumbsup:

There are 8 caps on that board.
 
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Just playing around with these four was actually enough to completely stop the popping. I've ordered replacements for all four.... and many, MANY thanks to you, sir!
 
Two things. One I usually put a lot of white space in a post, one sentence or two then a new paragraph. Easy to read. But Avionic has me beat, one sentence, and a new post. Great for post count. I could learn from that.

Oh, and Dave is right the rice crispies is the phono stage transistors. Just did that change on a completely recapped unit a couple weeks ago to make it just right. Nice units these 330 HKs.
 
I've got it cranked right now, clean and crisp as it ever was.

Might as well ask while we're here - the hum and lousy EQ/low volume on the tape channels, more likely to be bad soldering?

Thanks again guys!
 
There aren't very many components on the phono/EQ board in the HK330C. If you ever order more parts for something, you might want to do all the electrolytics and the known-noisy small signal transistors.

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It sounds like you've already solved the issue you had. The HK330C sounds great when restored, so if you didn't replace all the ecaps and naughty, noisy transistors, just know there is more you could do if you wanted to.
 
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