Sound issues with my stereo

amplifiers, receivers and loudspeakers
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sherbert_head
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Joined: 19 May 2019 02:48

Sound issues with my stereo

Post by sherbert_head » 19 May 2019 02:55

I was given a Harmon Kardon 330c stereo, and I want to get it to sound a little better. I sometimes hear some mild distortion (no matter what input source), and if I tinker with the volume or balance knobs, the sound becomes much more distorted. I have to kind of find a sweet spot for the distortion to go away.

Any suggestions on where to begin to try to eliminate this issue? Any help would be appreciated!

lenjack
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Re: Sound issues with my stereo

Post by lenjack » 19 May 2019 03:34

Let's keep in mind, this unit dates to the mid 70's. Do you know if the previous owner was using it with any success? Exactly what are you hearing when you tinker? Is it a scratchy sound, kind of an intermittent, cutting in and out sound? If so, it means those control have oxidized contacts and need to be cleaned. Very common on older equipment, and usually an easy fix, for any repair shop. Inexpensive. You can do it yourself for less than $20, if you're at all handy. Let's hope that's all it is.

sherbert_head
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Re: Sound issues with my stereo

Post by sherbert_head » 19 May 2019 04:12

Yes lenjack, it’s exactly as you describe; scratchy and cuts in and out when I tinker. Also, I don’t know if it’s just me, but the issue with the volume knob seems to have a sort of “warm up” period: when I first turn on the stereo, the volume knob seems sensitive and causes very loud scratchy distortion, but after a while, adjusting the volume knob won’t have much effect on the scratchiness (but the balance knob still does it).
The previous owner hadn’t used it for many years to my knowledge.

I’ll look into cleaning the circuits with help from YouTube, but if it seems like I’m in over my head I’ll probably bring it to a repair shop. Thanks for your help

vinyl master
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Re: Sound issues with my stereo

Post by vinyl master » 19 May 2019 04:47

If you need a decent repair shop (for future reference), sherbert head, let me know whereabouts you live and I could probably recommend one...Sounds like it might need some DeOxit, too...Here's a very good primer on that, if you intend to go the DIY route...

https://audiokarma.org/forums/index.php ... ed.207005/

georgesgiralt
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Re: Sound issues with my stereo

Post by georgesgiralt » 19 May 2019 05:20

Hello
These amps need a lot of big electrolytic condenser in their power supply. THese have a hard time and do not age very well.
Given the age of the amplifier, it may be wise to have it examined and, perhaps, have these caps replaced. This will improve the sound _a lot_
Just my 2¢

AsOriginallyRecorded
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Re: Sound issues with my stereo

Post by AsOriginallyRecorded » 19 May 2019 06:53

That is a fine gift if you manage to get it cleaned, lubed and operating at full capability. This is considered one of Harman Kardon's better early units and can be considered a real find if brought back to correct playing condition. The price of reconditioning by a qualified tech would definitely be worth it. A classic, and very collectible. Do try the cleaning and DeOxit yourself for the experience, and be thorough. Best of luck...and welcome!

Alec124c41
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Re: Sound issues with my stereo

Post by Alec124c41 » 19 May 2019 12:35

I had a 330, and it was a sweet sounding unit.
To do it yourself:
Unplug, and remove top cover.
Use the straw nozzle to get a bit of Deoxit 5, or other contact/control cleaner, inside each and every control and switch, and work said control back and forth several times.
Replace cover.

Cheers,
Alec

lenjack
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Location: Liverpool,PA

Re: Sound issues with my stereo

Post by lenjack » 19 May 2019 16:49

If you want to try it, it's not difficult, and you'll be very pleased with yourself. Check out that link. Also, you'll find Youtube videos showing how this is done on varying receivers. Be sure to unplug first if you try. This is an extremely common problem on older equipment, and easily remedied. If you can't find Deoxit locally, available on Amazon, and expensive, get CRC at Lowes.

pivot
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Re: Sound issues with my stereo

Post by pivot » 19 May 2019 17:34

What others have said....... Yes - unplug ---- and wait about an hour for the big capacitor in the power supply to bleed down to zero volts. Clean all controls with Deoxit. Work the controls on/off and over the full range of movement and spritz some more. Clean up extra spray outside the controls with lint free cloth. If you like the sound after cleaning consider investing in getting the power supply electrolytic capacitors replaced. Old electrolytic caps do not age well.

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