[Amps] Excessive Plate Voltage Henry 2KD-5

[Roland AH6RR]

Aloha Val,
Thanks for the reply. The repairs I did were replace the power cord hooked-up for 220V, all the High-Voltage wire as the old was dry and cracked. Some of the bleeder resistors had some bad solider connections so I repaired them they are all good R9 seems to be good I get continuity through it. I did test the voltage on the transformer before I reinstalled the HV filter bank and it checked fine @ 3100V with a Simpson 260 & a 5000V probe. It did not blow any fuses or trip the main breaker just smoked a filter cap and shorted one. I do belive it is the filter caps are just too old and have been sitting too long.
Thanks for the reply
Roland AH6RR
  ----- Original Message ----- 
  From: Val Erwin 
  To: Roland AH6RR 
  Sent: Saturday, December 12, 2009 2:07 PM
  Subject: Re: [Amps] Excessive Plate Voltage Henry 2KD-5


        Hi Roland:

        Suggest that you check the ac primary wiring to ensure that you have the amp jumpered for the proper AC voltage......I trust that you have it set up for 220 vac. (If-if you applied 220 vac to the primary with it wired for 110 vac, the DC voltage could shoot up and you would likely blow a fuse as well!!)

        I am suspicious of your wording: "...........after doing some repairs ,,,,,,,,etc,"  Suggest you go back and check your work especially if it was any rewiring!

        If you have a shorted capacitor, you are on the right track.........Due to the age of the amp, you really need to replace the caps (C1-C8) as well as the combo bleeder/equalization resistors (R1-R8) Also, while you are in the area, check the integrity of R9 to make sure it is still good.

        After you have replaced the caps/resistors, I would recommend that you pull the plate caps off of both 3-500Z's just in case the HV is still too high. (At this point, I am going to assume that your new tubes are still good.) Then, you can check your new HV reading after the component replacements with no fear of damaging the tubes.

        Is there any way of knowing this will fix the problem before you spend the $$?........No not really because there could be other things that are bad such as meter shunts, etc.  There is a test that you could run before replacing all the caps .....But, for safety reasons, I will not convey how to do that test because it can be dangerous if not experienced with HV and and amp repair/troubleshooting. 

        GL 

        Val L. Erwin / W5PUT
        Flower Mound, TX




        --- On Sat, 12/12/09, Roland AH6RR <Toesonnose at hawaii..rr.com> wrote:


          From: Roland AH6RR <Toesonnose at hawaii.rr.com>
          Subject: [Amps] Excessive Plate Voltage Henry 2KD-5
          To: amps at contesting.com
          Date: Saturday, December 12, 2009, 10:14 PM


          Aloha All,
          I have a Henry 2KD-5 that has been sitting for a few years and after doing some repairs and tube replacement  I turned it on and the plate voltage went to 4000V before I could turn it off. One of the filter caps smoked and now 1 has a short they all seemed hot, they are the orignal filter caps. I plan on replacing the all but I want to know if this will cure the problem. I checked the HV supply wiring and it is fine. Should I look at anything else?.
          Roland AH6RR
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