Harman Kardon hk 680i

Picked this up Thursday at goodwill. Tested it in store and noted the left channel out.

It's a Harman Kardon hk680i.


Got it home, opened it up and did a thorough look through. Did not see anything unusual until I looked at the bottom.
Yes those are 2 traces cut with a dremel tool. I jumpered the cuts but that did not make a difference. The left channel stayed just barely audible. Right was normal. removed the jumpers as this could have been a factory mod or maybe something done after market to fix a problem. There was nothing in the service manual about it.

Some research brought me to a thread on Audiokarma regarding the hk690i and that they have problems with dirty switches and pots. Deoxit did not help, but when I took some of the stereo apart I found a broken wire. Re-soldered that and viola it works. HOWEVER in taking it apart I broke the memory presets led circuit board that a previous owner had already broke and "fixed".

Re-soldered that and put it back together but now it has a new problem. It randomly looses lock on station goes to static and the tuner display does random stuff. I will maybe try and figure out whats wrong with it later. Definitely can't sell it as working. It sounds good contrary to some reviews on Audiokarma of it "sounding thin".

I later removed the memory presets LED board and the stereo works just fine but there is no LED indication as to which preset is selected. big deal.

This stereo has some interesting features.
An adjustable FM muting pot on the back, and a stereo separation adjustment labeled "Blend" that goes from Mono to Stereo. Kind weird to see on a stereo from the early eighties. I would expect it on something from the MPX days of the 60's.

1 comment:

HK said...

A bunch of the mid-eighties HK pieces used those pushbutton switches. If you get close to one of them, you will notice a small depressed dot at the top corner farthest from the push side. If you drill that hole very carefully with a bit just smaller than an aerosol straw (I take the added precaution of having the switch in the 'out'position) you can spray de-oxit/similar in there and get all of the switches to clean up. I noticed that one of my HK pieces returned from a "cleaning"with some of those corners slightly broken for access .... grr..... it is a much higher quality job if you just drill in that extreme corner where the round indentation is. You will not hit the slide contact set inside. Probably wise to put something tacky over that hole to keep dirt out afterward. Anyway, cleans those intermittent, sealed switches up.