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    Building, troubleshooting and testing of these amplifiers should only be
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HK Citation V schematic?

taj

diyAudio Member
Joined 2005
Neither Google nor the forum search is my friend today.

I've been looking around for a REAL Harman Kardon Citation V amp schematic, but all I can find in the Sams Photofacts version (like this one). It's everywhere. ...and no power supply included.

I also have the assembly manual that is floating around the internet, but curiously, it does not contain a schematic or any diagrams other than a drawing of the bottom plate, which isn't too exciting. The schematic is mysteriously absent, like Watergate minutes.

Anyone got the real schematic kicking around?

..Todd
 
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Yo Todd,
Yes, I have an original, but it's big. 11x17. I can scan it in two parts and email it to you directly. The forum is paranoid about posting original schematics. Tomorrow I will see if I can get a reduced copy of it as well. You'll have to send me your email addy through the forum. Or just send me a PM and I'll reply with it. Or I can snail mail a full size copy.

Victor
 
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taj

diyAudio Member
Joined 2005
Oh, okay. I didn't realize HK would still be protective (or even care) about a 50 year old schematic, considering the circuit itself is readily available. And here I consider myself quite anal about copyright protection, having been bitten by IP theft myself.

I'll PM yah. Thanks.

..Todd
 
Here's the requested schematic in two parts.

"HK Protective ?" I don't think so: the complete original assembly manual (29 pages) can be downloaded free from HARMAN KARDON's website:

Harman Kardon - Product Support - Select Your Product

Scroll down in "All Products" and select the model you're looking for. (Citation V)

Unfortunately it looks they didn't scan the big sized foldout pages and the schematic diagram is missing.

Most of the vintage (tube) HK manuals are available there for free download.
That's what I call real product support and HK should be congratulated for this service. There are not many manufacturer's around who still provide free manuals for 50+ years old obsolete products.
 

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Member
Joined 2004
Paid Member
Would the “REAL” Citation V schematic stand up please!

This is a very old thread, but in order not to start a new thread on the same topic, I would like to ask some help here.

The schematic in the post above seems different than the post by Jim McShane linked below, with regard to the connections with the front 12BY7A tube. Jim refers to an error in the Sam’s Fotofacts schematic for the Citation V, but I’m not sure I understand his “correction” correctly, and it appears different from the one above. Am I missing something?

See Jim notes at the bottom of the page: http://www.mcshanedesign.net/adjust5.htm

Does anyone know what the correct schematic is?
 
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This is a very old thread, but in order not to start a new thread on the same topic, I would like to ask some help here.

The schematic in the post above seems different than the post by Jim McShane linked below, with regard to the connections with the front 12BY7A tube. Jim refers to an error in the Sam’s Fotofacts schematic for the Citation V, but I’m not sure I understand his “correction” correctly, and it appears different from the one above. Am I missing something?

See Jim notes at the bottom of the page: http://www.mcshanedesign.net/adjust5.htm

Does anyone know what the correct schematic is?

As is often the case there is a manufacturer's schematic and and a SAMS Photofact folder schematic. Both are essentially correct even though they use different component IDs and exhibit some other minor differences.

As well, mistakes are often found both in both the manufacturer's and the SAMS schematics. Harman-Kardon (along with most other OEMs) made plenty of mistakes in the schematics they provided, and Howard W. Sams was no different.

So if you want to use the SAMS schematic you can do so successfully - once you are aware of the screen bypass capacitor connection mistake on their schematic.
 
Member
Joined 2004
Paid Member
Regarding the error in the SAMS Citation V schematic...

The 12BY7A screen bypass cap connection to both input stage tubes is drawn incorrectly. If you wire it up as shown, the screen bypass cap (C5, .47 uf) is out of the screen circuit. The screen connection is shown wrong, with C5 connected directly from the 420 volt source to the 470 ohm cathode resistor. This capacitor should go between the 150K screen resistor and the tube pin, pin 8 (the pin number isn't shown).

You can see a diagram of the correction on my website:

www.mcshanedesign.net/adjust5.htm

I’m really glad you are here to help straighten this out. Thanks very much for your reply.

The issue I raised was in fact the discrepancy between what I assumed was the original HK schematic that Eli Duttman posted above, let’s call it the HK schematic, and the corrected Sam’s schematic that you referenced above.

Eli’s shows the .47 uF cap between pin 8 and pin 1, i.e. between the screen and cathode. On your website you show two partial schematics, neither shows the cap between the screen and cathode. But you advise that the 0.47 cap should be between the 150k resistor (R10 in your posted partial schema) and the screen (pin 8).

So, is it true that the HK schematic had an error (connecting the screen via the cap with the cathode), and the Sam’s schematic (the first one on your website) had a different error connecting the cap between the feedback loop and the 420V supply?

Edit: While typing this directdriver posted the above. Thanks very much. I thought Jim’s correction breaks the connection to the feedback loop and inserted the cap between 150k resistor and the screen, pin 8. Now I think I understand Jim intention with the correction, based on your material directdriver. If Jim agrees, I think your schemas are clearer and should replace what Jim currently has.

http://www.mcshanedesign.net/fixed1.jpg

So, Eli, the HK schematic you posted is wrong? I wonder how all those original kit builders got all those Citation V’s correctly done, or did many go through life never knowing what they were missing?
 
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Member
Joined 2004
Paid Member
Thanks everyone! I believe I can now (when I get to it) build a Citation V clone with a bit more confidence wrt the 12BY7 wiring.

For anyone rebuilding, or trying to build a clone Citation V, TAJ’s rebuild thread will be very useful:

TAJ's Harman Kardon Citation V rebuild thread

In post #35, for completeness of HK schematic corrections:
“ My Citation V manual has a typed addendum sheet that states:

CITATION V ADDENDUM SHEET

Before proceeding with the construction of your kit please make the following correction to your schematic diagram:

Change the value of the following resistors from 1,000 ohms to 10,000 ohms.
R18, R19, R40, R41”

Additionally, in post #34 the output transformers are said to have 4k primaries. Does anyone have a definative answer regarding the outputs? I have a pair of Sonic Frontiers SFC1 output transformers with 4500 Ohm primaries (no UL) to 8R that I could use.
 
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Thanks everyone! I believe I can now (when I get to it) build a Citation V clone with a bit more confidence wrt the 12BY7 wiring.

Ah ha, an important tidbit of info. has surfaced. "Cloning" is going to be attempted.

The 12BY7 is out of production and is getting scarce. :( IMO, the available stock should be used in already existing units. :yes: The "hen scratch" 6922 cascode I'm uploading was specifically intended to replace 12BY7 voltage amplifiers in Mullard topology amps. ;)

Regulated B+ is shown, as PSRR in cascodes is essentially non-existent. VERY well filtered "juice" is a possible alternative. A buzz at 2X the power line frequency must not be added to the signal.
 

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I will enjoy this thread. I have what was an HK Citation V copy, not quite a clone as it used original transformers and slavishly copied the original down to the turret boards. I bought it thinking I would just get it "refurbed" but after digging into it I decided to use the trannies and build everything else new including DIY turret boards which I have already populated, I've rebuilt the power supply channel frame and purchased an auto-bias board from Erhard Audio. My top plate layout is ready and it it marked up and center punched but I haven't drilled/punched/sawed any openings yet. I will likely make a wood wrap base for it. I have tubes in my stash for the 9 pin set and I purchased a quad of 6L6GC-STR from Jim McShane. Someday I'll get it finished.

John
 
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