Harmon Kardon HK206 PC speakers

[banchang]

My Harmon Kardon speakers are securely plugged into my Dell PC tower using the green jack, however they regularly require the on/off volume wheel to be jiggled with to get volume to kick in on videos which I play on my PC - this is any videos, be they on Youtube, Facebook or news sites).

Volume cuts in & out periodically, & when this happens I note the green power light on the main HK206 speaker (the right one which houses the main connection to the PC & mains power) flickers & dims, until I turn up the volume & down again until it kicks in again.

Any thoughts on how to fix please ?

[Exim]

Re: Harmon Kardon HK206 PC speakers

You could start with checking the power supply. If it's plugged into the main speaker (instead of a fixed cable) so you can measure without disassembling: Does it deliver the specified voltage and amps, also if loaded? Also check for loose/broken cable or plug.

[lti]

Re: Harmon Kardon HK206 PC speakers

I looked back at the set of these speakers I recapped many years ago. The switch is a standby/mute switch. Based on your description, cracked solder joints would be my first guess. The power jack or switch could be dirty or broken, but that isn't likely since adjusting the volume temporarily fixes it.

[momaka]

Re: Harmon Kardon HK206 PC speakers

Most likely a bad solder joint in the speaker with the volume pot. Open it up and check. Better yet, post some high-res pictures of the board here, if possible. Then we may be able to see if that is the case or not.

[nomoresonys]

Re: Harmon Kardon HK206 PC speakers

Have these, one speaker not working, non-working speaker cable and rca male end verified on a tv, not sure how to verify rca female jack on the pcb, anyone know what the voltages of the 2 IC's should read?

[budm]

Re: Harmon Kardon HK206 PC speakers

Good clear hi-res of the top and bottom side of the board will help.
IC P/N?

[nomoresonys]

Re: Harmon Kardon HK206 PC speakers

My good camera is broke, pcb is very small, one is TDA1517P, data sheet: https://cdn.badcaps-static.com/pdfs/...829e8f7c2d.pdf Other is LM324N, data sheet:
https://cdn.badcaps-static.com/pdfs/...14850e2645.pdf

[nomoresonys]

Re: Harmon Kardon HK206 PC speakers

Think I'm going in reverse, now both speakers don't work, wasn't getting a steady 12 volts out of my power supply, would flash 18 then go zero when tested, tried a variable power supply was putting out 16v when set on 12, same results no sound.

[nomoresonys]

Re: Harmon Kardon HK206 PC speakers

Can get these silly things for 10 bucks, not really worth the effort, I just like trying to figure out these little mysteries.

[nomoresonys]

Re: Harmon Kardon HK206 PC speakers

Found a couple nice closeup pictures of the pcb, if you click it enlarges: https://www.ifixit.com/Guide/How+to+...567-4822/64203

[Logistics]

Re: Harmon Kardon HK206 PC speakers

Actually, these are the best (in their class) 2.0 speakers I have ever had in my listening space. I, too had issues with the power wire, IIRC, and had to take it in a certain position so it would keep contact. I had opened them once already, to fix the solder joint on the volume potentiometer. I still have my set under my desk, and intend to rework them. I got my set off a bargain rack for $3! $1 for each speaker, and $1 for their wall-wart. They have a built in volume regulation that allows you to crank them.

[nomoresonys]

Re: Harmon Kardon HK206 PC speakers

Yes I had to put the wire a certain position and leave it there, now it don't matter where I put it, no sound, then was messing with it got a bit of the green squares of capacitor C11A jacked up, not sure if it's got the proper connection to the traces now, no sound from either one. Such a small board, hard to check the resistors n such.

[nomoresonys]

Re: Harmon Kardon HK206 PC speakers

Good pictures in post 11, not sure what the voltages of LM324N and TDA1517P should be, those being responsible for amplification I think one may be bad?? Crazy coincidence paid 3 bucks for mine too at an estate sale.

[nomoresonys]

Re: Harmon Kardon HK206 PC speakers

Possibly let me know when you rework them, maybe we can compare the voltages on those ics.

[lti]

Re: Harmon Kardon HK206 PC speakers

The board in those pictures is slightly different from the one I fixed, but the component designators are the same.

C11A is one of the output caps. If the trace is broken, you will be missing sound from the right channel.

Since they're completely dead, check the power supplies and the TDA1517 standby/mute pin (pin 8) first. The power pin of the TDA1517 is connected directly to the DC input jack, so you should see full supply voltage at pin 7. There should be at least 8.5V on pin 8 when the switch is on. The LM324 power is switched, and R102 is in series.

[nomoresonys]

Re: Harmon Kardon HK206 PC speakers

Thanks Iti, I checked with power on, TDA1517 pin 8 is 14.5, pin 7 is 15.5, I checked them all there's no reading on pins 10 thru 18.
1-1.9
2-0
3-7.5
4-7.5
5-0
6-7.5
7-15.5
8-14.5
9-1.9, 10 thru 18 = 0
LM324N
1-7.3
2-7.3
3-7.1
4-14.7
5-6.1
6-7.3
7.3
8-7.3
9-7.3
10-6.1
11-0
12-7.1
13-7.4
14-7.4 My 12v power supply is reading 16v.

[nomoresonys]

Re: Harmon Kardon HK206 PC speakers

Do you think that TDA1517 is bad, seeing that there's nothing from 10-18?

[R_J]

Re: Harmon Kardon HK206 PC speakers

Here, this will help

[momaka]

Re: Harmon Kardon HK206 PC speakers

Do you think that TDA1517 is bad, seeing that there's nothing from 10-18?

No.

Pins 10-18 are simply not used on the 18-pin version, so of course you shouldn't get any voltage on them. See the datasheet that R_J posted above, please.

From what I see, those voltages readings on your TDA1517 amp IC all look normal to me. You can try disconnecting whatever circuit is connected to pins 1 (-INV1) and 9 (-INV2) - probably a coupling capacitor going to the LM324 IC - and then connecting your own coupling capacitor (220 nF to 2.2 uF should do the trick) and connecting an audio source (line level) directly to that. With this, you should hear sound coming out of both speakers.

This should help you isolate the issue, whether it is in the input cabling somewhere, the LM324 IC (very unlikely), the amp TDA1517 IC (again, very unlikely), or the output cabling.

[nomoresonys]

Re: Harmon Kardon HK206 PC speakers

Messed this up by trying to work on this small shit, lost patience and screwed it up, lifted these 2 pads. Do you think It can be fixed with copper tape, not sure how to attach or ? Borrowed the excellent detailed picture from Iti, thanks.