How to Fix Your Stereo Amplifier (Harman Kardon HK 620)





Introduction: How to Fix Your Stereo Amplifier (Harman Kardon HK 620)

My stereo amplifier quit amplifying over the weekend. The LEDs still lit up, and it would still pass audio through the "tape out," but nothing went to the speakers. So, I decided to take it apart and see what I could find...

Step 1: Open It Up

Pull the cover off, and expect to find something obviously wrong.

When there's nothing obviously wrong, make disapproving noises and have your house-mate phone his brother to see if the brother still has an extra amplifier. When it turns out he doesn't, carry on to step 2.

Step 2: Vacuum Out All the Dust

I've had this amp since at least 1996 and it's never been opened, so that's plenty of time to accumulate some serious dust.

Vacuum out all the innards. Wire it back up and be amazed that all the channels now work.

Step 3: Reassemble

Put the cover back on and reconnect everything. Expect another 10 years of service before next cleaning.

Update: It has stopped working again twice since I originally wrote this, and both times vacuuming it out has fixed it.
Jan. 2008 - vacuumed, fixed again.
Feb. 2009 - vacuumed, didn't fix, vacuumed more vigorously and it fixed
Feb. 2009 - a week later it stopped working, and I vacuumed it gingerly, which fixed it.

There's no visible dust inside the amp. I don't think it's a loose wire because "pretend" vacuuming (or shaking for that matter) has no effect.

I posted a question about why this work here:
My integrated stereo amplifier periodically stops working. Why does vacuuming it out fix it?



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    I have the same amp. Stopped working a few years ago. Never though of vacuuming it. Will try this weekend!!

    Will be sweet if it works!

    1) Vaccuum your equipment can cause damage due to ESD from the vaccuum cleaner! Use canned air or a compressor!

    2) If vaccuuming 'fixes' your amp, there are other issues with it (probably loose solder contacts) that need to be fixed.

    Same thing happens with my sister's digital camera. Dust accumulates and nothing ever works. I will definitely remember this for any problems I encounter with electronics. My, those are HUGE capacitors. -Brennn10

    Holy frack, yeah those are huge.

    meh those are nothing, i picked up a couple of 500vdc 1200uf caps for my coilgun project and their almost the size of pop cans, and ive seen much bigger than them.

    I've seen capacitors rated at 2vdc and 3000F!!!!!!! they are used in the industry like in trains?!


    Those look like power filter caps. You really do not want to mess around with them.

    Have you ever thought that vacuuming might pull away the static charge?

    Hi , my pioneer amplifier A-443 works fine but the treble and the bass not working. And also a tick sound from inside always 10 or 15 second before another tick sound. I love to put some bass on songs but only the volume control the sound. Can you help me please.


    My dad used to work for pioneer but then they went out of business in the UK so possibly could have asked him to have a look at any datasheets for it and common problems ;)