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Harmon Kardon Cit-II Trouble Shooting Question

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So I have a Cit-II that had been fully restored with new Gold Lion KT-88's, to include smaller tubes. Trying to determine if it is a circuit failure, a simple bad tube, or I should have monitored the biasing closer for new tubes.

After approx. 180 hours developed noise in one channel. Wiggled V-9 and determined it was the problem. Tried to pull it and it was stuck. Finally came loose but the large plastic center pin broke off and had to be driven out with a wooden dowel (ahh, over heated, tube appears burned but never noticed any redness when running).

So, can I determine if it was a simple faulty tube by just pulling all of the KT-88's, firing it up, and comparing voltages at the pins to the other KT-88 sockets? And should I do this leaving the small tubes in place?

Thank you in advance, Charlie8521

Follow Ups:

RE: Harmon Kardon Cit-II Trouble Shooting Question - blownrx7 14:23:56 11/11/22 (1)
Holy cow! Those resistors are fried!!! Need to replace those resistors before you sacrifice anymore tubes!
- So the question becomes ... - Charlie8521 07:29:31 11/12/22 (0)
  Was it a bad tube that took them out, or some other failure in the circuit? Have a fantastic tech that will be looking at it.
RE: Harmon Kardon Cit-II Trouble Shooting Question - fredtr 08:02:43 10/28/22 (2)
That's good advice on bringing it up. Also look at the resistors that are connected to the pins on the tube that you are replacing for indications they have gotten hot. I lose a Gold Lion KT-88 on my Citation about once a year or so and they almost always burn two of the resistors connected to the tube.
- So how bad does this pic look to you of socket wiring? - Charlie8521 06:42:12 11/09/22 (1)
  see attached image.
  - RE: So how bad does this pic look to you of socket wiring? - The Dill 15:14:44 11/09/22 (0)
    Everything in that photo needs to be replaced.
RE: Harmon Kardon Cit-II Trouble Shooting Question - 6bq5 10:49:37 10/27/22 (1)
Ideally you have a spare set of tubes - even some 6550s lying around?
I would load the spare and with the bottom open and accessible for measuring - bring it up on a variac to about 1/2 power and see where the voltages are-

It is very likely a bad tube- but it could be a bad cathode resistor...
Happy Listening
- RE: Harmon Kardon Cit-II Trouble Shooting Question - Charlie8521 14:21:57 10/27/22 (0)
  Thank you for the good input. Already got a new matched pair of KT-88's from Jim McShane and I have a Variac. So hoping it was just a bad tube and I can be on my way.

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