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  #1  
Old 04-08-2011, 11:30 AM
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Louie7 Louie7 is offline
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HK Two-Thirty Receiver distortion

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.

Thanks.
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Old 04-08-2011, 07:42 PM
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Both channels distort? Do the lights dim when this happens?
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Old 04-08-2011, 10:04 PM
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Quote:
Originally Posted by ryuuoh View Post
Both channels distort? Do the lights dim when this happens?
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.

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Old 04-09-2011, 02:03 AM
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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...................



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Old 04-09-2011, 02:26 PM
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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".

Rick
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Old 04-09-2011, 02:51 PM
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Originally Posted by rickknight View Post
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".

Rick
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's......wow.

I'd still like some idea of the date of mfg..... The ink stamped number 7341192, on the back, starts with 73...so 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 by Louie7; 04-09-2011 at 02:58 PM.
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Old 04-09-2011, 06:42 PM
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KentTeffeteller KentTeffeteller is offline
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Apparently the last non-Citation line HK made in Plainview, NY. Nice looking units and likely nice sounding and well built.
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Old 04-09-2011, 07:25 PM
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Originally Posted by KentTeffeteller View Post
Apparently the last non-Citation line HK made in Plainview, NY. Nice looking units and likely nice sounding and well built.
yeees... nice sounding except for the distortion....
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Old 04-09-2011, 09:41 PM
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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.

Rick
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Old 04-09-2011, 11:48 PM
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I would suspect a common element, like the power supply.
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Old 04-10-2011, 04:06 PM
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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.
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Old 04-10-2011, 06:16 PM
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thanks guys.... it's scary, cause I work almost exclusively on tube stuff.....
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Old 04-10-2011, 11:29 PM
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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
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  #14  
Old 04-10-2011, 11:35 PM
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It shouldn't be too hard. Try replacing the power supply caps (including the filters) and see if the problem is lessened.
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Old 04-12-2011, 08:10 PM
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Quote:
Originally Posted by GuyK View Post
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.
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.
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