HK Two-Thirty Receiver distortion

Discussion in 'Solid State' started by Louie7, Apr 8, 2011.

  1. Louie7

    Louie7 Active Member

    Yesterday I snagged a sweet little mid 70's Harman Kardon Two-Thirty receiver in very clean shape and it works.

    Only issue is distortion. If I set the bass control at anywhere below about 12 o:clock (50%) and keep the volume moderate, it's listenable, but still kind of rough..... but increasing the bass and volume brings in massive distortion.

    The amp doesn't hum badly, and the big filter caps haven't leaked or exploded, although I do plan on replacing them, I DON'T think that's where the problem lies.

    Anyone to suggest possible places to look?

    As you know, this is a SS unit. My skills are more along the tube/point to point wiring, so I hope the solution is more capacitor related than transistor related. But hey... I'm open to suggestions.

    I've replaced power transistors before, but it always makes me nervous.

  2. ryuuoh

    ryuuoh FFXIV Summoner Subscriber

    Both channels distort? Do the lights dim when this happens?
  3. Louie7

    Louie7 Active Member

    Yes sir... both channels distort... Lights do not dim... distorts during AM, FM, FM Stereo, and AUX play. Haven't tried the phone inputs, but assume the same, or worse.

    The pots aren't even scratchy...even though this unit probably sat negected in a garage for years, possibly.

    Here's a picture of the unit I grabbed from the web (thank you whoever you are) ;) I'll get some pics of my own when I get some spare time. I think it has a nice clean look. Black dial faces seem to be looked upon with favor around these parts, and mine is rather clean and fresh looking, as opposed to this one which appears to be missing a knob.

  4. Louie7

    Louie7 Active Member

    I took some pics. Anyone guess what year this was produced ? I thought early 70's... some website suggested 60's. That's a bit vague. :) Anyone know the exact year ? 1973 perhaps ? Thanks...................


  5. rickknight

    rickknight Active Member

    Interesting, I have a Harman/Kardon 230-a. It looks like the same receiver except the model on mine is "230-A", not "Two Thirty". Mine has one dead channel and I plan a recap for it but I have not been able to find a service manual or schematic for a "230-A". Maybe I'll try searching for "Two Thirty".

  6. Louie7

    Louie7 Active Member

    I agree..

    What I discovered was that googling "Two Thirty" instead of "230" produced more results. But not entirely.

    I saw pictures of receivers that looked like mine called 230 and 230a, main difference seemed to be silver knobs instead of black knobs (like mine).

    As you can see, the unit is called a 'Two Thirty' in front and '230' in back.
    To add to the mess, most of the search results I get are for completely different units that are called A230.

    Then there is the issue of 'Nocturne'. Evidently HK called some of these units 'Nocturne', but they don't really say 'Nocturne' anywhere on the unit as far as I can see, and that designation seemed to have been reserved for literature, and manuals ?

    Confusing. Too many products with similar names and difference dressing. Plus, all my searches tend to bring up 330's, A330's and/or 330a'

    I'd still like some idea of the date of mfg..... The ink stamped number 7341192, on the back, starts with I'm guessing that's it. The serial number is a four digit number on a piece of paper glued to the under side of the AM antenna (not shown in my picture)

    If I'm reading the code correctly, which I doubt, it might mean the 92nd unit made on April 11th, 1973.
    Last edited: Apr 9, 2011
  7. KentTeffeteller

    KentTeffeteller Gimpus Stereophilus!

    Apparently the last non-Citation line HK made in Plainview, NY. Nice looking units and likely nice sounding and well built.
  8. Louie7

    Louie7 Active Member

    yeees... nice sounding except for the distortion.... :no: :smoke: :D
  9. rickknight

    rickknight Active Member

    Mine says 230-a on back. It does have the silver face below the black dial face. The one channel that does work sounds pretty good, no distortion. I have 2 other recapping projects ahead of this one, an H/K 630 Twin Power that's just about done and a TEAC A-4300 that I've just started on, then I'll start on the 230-A. I'm still hoping to find a service manual, but I've been told that the H/K 330A uses the same control/driver board so I'll try that.

  10. ryuuoh

    ryuuoh FFXIV Summoner Subscriber

    I would suspect a common element, like the power supply.
  11. GuyK

    GuyK Super Member

    This looks identical to my 330b, except black instead of brushed aluminum face. I would suspect the 230a & 330a only differ cosmetically. Try downloading a manual for a 330a (or even just certain pages) & comparing the pictures of the PCBs to the real thing. I had a similar problem with mine that turned out to be output transistors. Very inexpensive, quick repair.
  12. Louie7

    Louie7 Active Member

    thanks guys.... it's scary, cause I work almost exclusively on tube stuff.....
  13. jimbofish

    jimbofish for TRULY GREAT MUSIC

    Looks like it says "Made in Japan" on the back... right below the power cord.

    Just wondering if this model has pcb's or is it hard-wired below the chassis like my "Seven Twenty" ? HK doesn't seem to have manuals for these older series on their website :sigh:
  14. Sir.Byrd

    Sir.Byrd Lunatic Member

    It shouldn't be too hard. Try replacing the power supply caps (including the filters) and see if the problem is lessened.
  15. rickknight

    rickknight Active Member

    Thanks GuyK, I've downloaded a manual for the 330A. I'll have to bring the 230A in from the garage and compare it to the 330A diagrams,

    Thanks again.
  16. jbehr

    jbehr New Member

    I do believe I bought a model two thirty, not the 'a', in 1973. It was my first reciever.
    I am sure of the year but only fairly certain that it was not an 'a' model. If I remember this is a 15 watt reciever.
  17. boreas

    boreas AK Subscriber Subscriber

    No, the 330A is a larger receiver. I believe it has more power, 22WPC vs. 15(?)


    Attached Files:

  18. GuyK

    GuyK Super Member

    Ah, now we know. I also forgot the 330 series (a & b at least) have pre / main jumpers. My apologies for leading anyone astray.
  19. Louie7

    Louie7 Active Member

    Fine.. thanks everyone...

    here's the latest. I replaced all the BIG electrolytics (seven total) and while I was bringing it up on the variac (just to be safe), I plugged in the headphones and started listening for distortion as soon as the AC level increased enough to produce sound.

    What I got was huge, pure, beautiful sound, so I assumed that the distortion problem was solved. But disappointment set in when I attached spkrs and got the same distortion as before.

    But the first thing I noticed is two things....

    a. The speakers only cut in when the headphones are unplugged, and when you plug the headphones in, the speakers cut out.

    b. When you unplug the headphones, the amp produces a slight buzzing sound, even when the volume is down.

    I'm guessing that the headphone jack is jimmied somehow and is shorting somehow to cause the distortion.

    Aren't the speakers supposed to stay active when you plug in headphones ?

    THANKS... L7
    Last edited: Apr 16, 2011
  20. Sir.Byrd

    Sir.Byrd Lunatic Member

    No, sometimes the headphone jack is wired as a switch to disconnect power to the speakers when headphones are plugged in.
    Odd that it is fine with headphones, this makes me think it is a problem with the amp section.

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