Harman Kardon 230A FM Board Curiosities

[Johnny_Law]

So I decided to save this 230A. It got a complete re-cap (pending a larger main power supply cap, ordered the wrong size) and new bulbs and a bath. It sounds (mostly) fantastic. I'll post some pictures of the rebuild below.



However, this wouldn't be as much fun without some mystery. Here's the mystery: when I put the AM-FM IF PCB back together, I find myself (a) missing a variety of components indicated by the manual, (b) questioning whether the board layout matches the circuit diagram, and (c) having some extra components that don't belong anywhere according to both!

I wish I had taken more stock of the original board before I took it apart. I naively assumed it had the components the service manual indicated, and that the board matched the circuit diagram. Ha! Joke's on me.

Here's what it looked like before / after (both tuner board came apart in order to clean them).



Here's what's missing. What's that? Only 5 things missing from circuit, but 10 missing according to the board layout? Yeah. *Scratching my head* ... And, the FM meter circuit is totally not the same between the two. Try to map the FM meter circuit on the board (pin 11) to the circuit. T106 to D106 ... nope ... to R119 / C134 ... double nope ... uhh?



Looking underneath the original IF PCB, note the complete absence of any components or solder on those strips!



And look closely at this close-up pic I took before pulling it apart ... no components in those locations!



So ... did this never have an operational FM meter?

 

[Champco]

The board may have been made for more than one purpose/tuner/receiver. There may have been design changes during production which was not uncommon.

 

[Johnny_Law]

Thanks, yeah I've been searching online for 230A boards and found at least one (on ebay actually) that looks populated differently (with these missing components in place!) ...

And I forgot to mention, a random capacitor on the backside of the IF PCB (second from last pic above, on left side). I didn't put it back in place since it doesn't appear in the circuit diagram. Maybe a factory modification? I could see what happens if I put it back.

My plan, although FM/AM are operational without them, is to replace the components that actually appear in the circuit diagram, and order the rest of the missing components to see if I can figure out how to get the FM meter to work.

 

[dlucy]

Nice work!

The 230 and 330A have a real jumble of devices on the PCB.

I can tell you there are quite a few, maybe even 20%, of the board-labeled components NOT installed on the 330C. It operates correctly even without them.

Additionally, the 330A and 330B often have different boards installed than the service manual covers. I wouldn't be surprised at all if your barely-earlier HK didn't end up with the same post-manual changes.

 

[century tek]

What looks like missing or no parts on the board is just production changes and usually has nothing to do with the way the device operates. I would go by the board and not by the manual as it came out of the factory this way.

 

[Johnny_Law]

Thanks - I guess what I'd love to see is pictures of other 230A IF PCBs? Anyone have a 230A and don't mind snapping a pic? My goal at this point is just to make sure I have a complete circuit in there and to get the signal meter to work for FM (it is functional for AM).

 

[dlucy]

Thanks - I guess what I'd love to see is pictures of other 230A IF PCBs? Anyone have a 230A and don't mind snapping a pic? My goal at this point is just to make sure I have a complete circuit in there and to get the signal meter to work for FM (it is functional for AM).

Huh. Im just now remembering that I do have a 230, somewhere in the stack in the storage bin. I'll try to visit the bin tonight and get you some photos.

 

[Johnny_Law]

After some Internet Sleuthing, I've found a couple pictures showing a similar lack of components between T103 and T102 ...

http://audio-room.net/harman-kardon-230a/

https://www.audiovintage.fr/leforum/viewtopic.php?t=56322

So I guess my next step is to trace my meter dial and see where it hooks into the board (if anywhere)?

 

[dlucy]

Wow, you are quick! I barely got my 230 buttoned back up and stuffed back in the storage bin when you posted the above.

I've copied the dozen plus images of my 230 and put them up on Google Drive for you and others to peruse (the ones on Google are higher resolution):

https://drive.google.com/drive/folders/1F_wEUIF2Yl5z_fCbr6v1pmWfU-l-fUxz?usp=sharing
​

The most-relevant (I think) images are attached.

Sorry they are so dirty. I didn't have time to clean the unit out before its glamour shots.

 

[Champco]

Wow, you are quick! I barely got my 230 buttoned back up and stuffed back in the storage bin when you posted the above.

I've copied the dozen plus images of my 230 and put them up on Google Drive for you and others to peruse (the ones on Google are higher resolution):

https://drive.google.com/drive/folders/1F_wEUIF2Yl5z_fCbr6v1pmWfU-l-fUxz?usp=sharing
​

The most-relevant (I think) images are attached.

Sorry they are so dirty. I didn't have time to clean the unit out before its glamour shots.

You were right. It's dirty.

Makes me curious how many HK's you have piled up???

 

[dlucy]

You were right. It's dirty.

Makes me curious how many HK's you have piled up???

Well... I am now separated, so I think the answer is "too damn many."

Here are months old photos that omit the third stack added since then. I'd ask "how many is too many?" but I don't think I want to know the answer.

 

[Champco]

Well... I am now separated, so I think the answer is "too damn many."

Here are months old photos that omit the third stack added since then. I'd ask "how many is too many?" but I don't think I want to know the answer.

UUUUGGHHH Those poor receivers on the bottom. Separated as in 50/50? Need to recapp, fine tune,, $$$ Make lemonade.

 

[dlucy]

Well, that KR-6170 jumbo jet on the bottom is like a concrete brick. It can take a lot. As for not getting to it anytime soon, the receiver and I came to an agreement when I first looked inside: I promised not to start the restore on it until I'm more experienced and it promised not to get any MORE complex inside in the meantime.

 

[dlucy]

UUUUGGHHH Those poor receivers on the bottom. Separated as in 50/50? Need to recapp, fine tune,, $$$ Make lemonade.

You're right! I am WAY overdue for a recapping.

 

[Champco]

You're right! I am WAY overdue for a recapping.

So how far have you driven to snag another HK piece???

 

[dlucy]

So how far have you driven to snag another HK piece???

Hmm... well I drive back and forth from Philly to VA about once a month and many of my funds have been along that corridor... so 200 miles perhaps?

I did drive up to Frankenfest last year and that was WAY more, but I don't think I brought back any HK gear that time.

Most of my HK purchases have been off eBay.

 

[dlucy]

After some Internet Sleuthing, I've found a couple pictures showing a similar lack of components between T103 and T102 ...

So I guess my next step is to trace my meter dial and see where it hooks into the board (if anywhere)?

How did that go?

 

[Johnny_Law]

How did that go?

Great!

I traced the FM dial meter to this, which makes sense looking at the circuit diagram.



Then I dug up a 12K resistor for R120, put in the spare 4k resistor at R109, used my spare 5P capacitor at C104, and put the 0.01uF capacitor back as noted.



Viola! FM sounds awesome, strength meter works great, all is well.



And, wow. This 230A sounds awesome!

I listened to Pink Floyd - Division Bell on vinyl last night, with my AR-XA (Shure M75ED TypeII). I was floored. This sounds so rich, warm, and musical, it's crazy. I used Nichicon KL caps throughout, except for the 1uF/50V caps (many of them on the pre-amp / amp board) which are Nichicon FG.


Ryan

 

[dlucy]

Out-standing! Well done.

 

[Champco]

Great!

I traced the FM dial meter to this, which makes sense looking at the circuit diagram.

Then I dug up a 12K resistor for R120, put in the spare 4k resistor at R109, used my spare 5P capacitor at C104, and put the 0.01uF capacitor back as noted.

Viola! FM sounds awesome, strength meter works great, all is well.

And, wow. This 230A sounds awesome!

I listened to Pink Floyd - Division Bell on vinyl last night, with my AR-XA (Shure M75ED TypeII). I was floored. This sounds so rich, warm, and musical, it's crazy. I used Nichicon KL caps throughout, except for the 1uF/50V caps (many of them on the pre-amp / amp board) which are Nichicon FG.


Ryan

Nice report.
Of all the capacitors you replaced were you able to test them and were there a lot out of spec?? How many actually looked bad??
Did you replace any transistors? Happy for you it came out good. I was a bit concerned with what all you were doing.