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My HK Citation2 meter quit working

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Posted on June 9, 2015 at 21:52:12
DAK
Audiophile

Posts: 2712
Location: PACIFIC
Joined: August 8, 2010
 I don't know why but just the other day I moved the knob to check the bias readings and the pointer was nowhere to be seen. I looked hard and saw it way off to the side. So, I checked the wiring and all looks good there. Everything seems to be as it should be. I have not checked if there is voltage going to the meter and I will do that tomorrow.
Worst case Scenario. If the meter is dead what are my options? Of course if I can get one from JM or elsewhere would be best. If none is available is it repairable? What about installing a test jack and just using the input to the meter on the test jack, then use my DVM to make the readings? Any help will be appreciated. Thank you , Dak

 

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RE: My HK Citation2 meter quit working, posted on June 10, 2015 at 10:15:54
AJ
Audiophile

Posts: 532
Joined: February 24, 2001
 Hi,


Unfortunately, there are no mechanical reproduction replacement meters for the Citation II that are of the right form factor. I am pretty sure McShane offers a solution for the Citation V .. none available for the Citation II.

It is not uncommon for these meters to fail they are exceedingly difficult to repair. Dust or some other particles can get in the movement or worse- the coil burns out.

Determine if there is indeed voltage going through to the swith movement and then the meter. If so, and the meter is unrepairable then the best solution is test points and a good DMM or you could possibly use a digital panel meter - about $10-$15 that would fit the through the existing hole with a stud mount and some creative bezel work with some plastic sheet or fiberboard etc. You would need a 9v dc supply that could be a battery.

All doable and could be an interesting project.


Goodluck.

 

RE: My HK Citation2 meter quit working, posted on June 10, 2015 at 11:16:41
DAK
Audiophile

Posts: 2712
Location: PACIFIC
Joined: August 8, 2010
 Hi AJ, and thank you for the tip. Putting in an aftermarket milliampmeter might be neat. I will check if there is something close to the size of the original meter. I was thinking of just installling a test jack and using my meter but I am not sure of what the current or voltage that I should be aiming for that corresponds to the stock meter reading.
I was hoping JM had a fix for this. How about it Jim? Is there a replacement in the works that I should wait for? I am sure there must be a great need for it. Cheers, Dak

 

RE: My HK Citation2 meter quit working, posted on June 10, 2015 at 12:51:56
elflow
Audiophile

Posts: 354
Location: Indiana
Joined: November 1, 2005
 Hi,
A modern external meter is more accurate, but even if you go that route, a working internal meter is nice for a quick check to see if a bias adjustment is needed.
All that said, if you have a later production unit with the small rectangular meter, the lugs on the meter where the wires are connected is attached to the meter with small screws, try tightening those two screws a little.

 

RE: My HK Citation2 meter quit working, posted on June 10, 2015 at 15:26:49
Tre'
Industry Professional

Posts: 17305
Location: So. Cal.
Joined: February 9, 2002
 The Cit 2 uses 15 ohm cathode resistors on the output tubes.

The meter is just reading a voltage across those resistors so, using ohms law, 1.5 volts would be 100ma of current and .75 volts would be 50ma.

Current in amps = voltage / resistance

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: My HK Citation2 meter quit working, posted on June 10, 2015 at 17:01:04
DAK
Audiophile

Posts: 2712
Location: PACIFIC
Joined: August 8, 2010
 Hi Tre, yeah, I have previously calculated my kt90 power tubes dissipation at nearly 100ma when the meter needle was centered on the "bias indicator line". I guess what I wanted to know was what the design goal of the bias current? I answered my question when I calculated the bias for the kt90 tubes. cheers, Dak

 

RE: My HK Citation2 meter quit working, posted on June 14, 2015 at 18:12:32
Jim McShane
Dealer

Posts: 5910
Location: Chicago
Joined: January 13, 2003
 There are no new meters available for the Cit II, and none in the pipeline. It is FAR better to rig up a set of tip jacks and replace the stock meter with your own DMM. It is more accurate and more dependable - and it can be set up to continue to use the selector switch to allow easy checking of all the different tubes' bias settings.

Those little meters were just barely usable when brand new (fine for bias, not so fine for AC balance); many of them read WAY off now. The YOUNGEST Cit II in the world is 50 years old, keep that in mind!

 

RE: My HK Citation2 meter quit working, posted on June 14, 2015 at 21:21:53
DAK
Audiophile

Posts: 2712
Location: PACIFIC
Joined: August 8, 2010
 hI Jim, thank you for the tip. If I put in a test jack do I just run the meter supply wire, the grey wire I believe, to the jack? Cheers, Dak

 

RE: My HK Citation2 meter quit working, posted on June 15, 2015 at 15:36:22
Jim McShane
Dealer

Posts: 5910
Location: Chicago
Joined: January 13, 2003
 You need one test point for each meter terminal. If you look at the meter you'll see one lead comes from the selector switch and the other lead goes to ground through a resistor.

You need a tip jack to access the lead from the switch and one to connect to the meter lead that goes to ground. The wires go to the jacks and no longer connected to the meter, you are correct. For the best accuracy you need to get a direct ground connection, so bypass or remove the 300 or 330 Ohm resistor that goes from the meter to ground.

Then when you plug in your DMM to the jacks read the bias voltage, the switch allows you to measure any of the four tubes. And it's way more accurate.

 

RE: My HK Citation2 meter quit working, posted on June 18, 2015 at 10:31:41
DAK
Audiophile

Posts: 2712
Location: PACIFIC
Joined: August 8, 2010
 Thank you for the help, Jim. I did install the tip jack right next to the meter and soldered the red wire to it. I checked the reading at the cathode of the power tube and compared it to the reading at the tip jack and found the difference to be negligible. So, even with the resistor in place its effect is not very much. Cheers, Dak

 

RE: My HK Citation2 meter quit working, posted on June 18, 2015 at 13:40:07
Jim McShane
Dealer

Posts: 5910
Location: Chicago
Joined: January 13, 2003
 That's correct about the resistor. I'm glad to hear it all worked out for you.

 

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