kiphartzell
New member
Another Amplifone "help" thread..... Is this tube toast?
I have been working on a 25" Amplifone set up for my SW and seem to be having a high voltage problem. Both the Deflection and HV cards have been rebuilt/capped using Michael's FAQ. The HV board is Biege with a Penn Tran HVT (with proper Diodes and 50ohm resistors). The BU406D, voltage regulators and caps are new and the Wx was replaced with wire. The Deflection seems to be working as I hear the typical sounds. The problem is no HV (or at least when the anode cup is attached to the tube. The Penn Tran rings fine with a LOBT blue tester. A couple of observations, the "heater" color is purple/lavender in the tube neck. Is this normal? I may have a blue gun shorted as I only see 2.3ohm between pin 10&11 (I get a 1 ohm reading between pins 9 & 10). Besides this potential gun short. Here is the real odd thing. I get no HV when the anode cup is attached to the tube (I do have +/-24v), but I get 19+kv when I pull the anode cup off the tube and measure it with the HV probe. So the HVT is generating the HV, but something is shorted that does allow the tube to work.
Is my tube toast? Will a rejuvenater fix this type of issue? I just picked up a B&K 490 (still waiting for it to arrive) to attempt to fix the blue gun, but have doubts that I can get this tube working with this other HV anode issue.
I have been working on a 25" Amplifone set up for my SW and seem to be having a high voltage problem. Both the Deflection and HV cards have been rebuilt/capped using Michael's FAQ. The HV board is Biege with a Penn Tran HVT (with proper Diodes and 50ohm resistors). The BU406D, voltage regulators and caps are new and the Wx was replaced with wire. The Deflection seems to be working as I hear the typical sounds. The problem is no HV (or at least when the anode cup is attached to the tube. The Penn Tran rings fine with a LOBT blue tester. A couple of observations, the "heater" color is purple/lavender in the tube neck. Is this normal? I may have a blue gun shorted as I only see 2.3ohm between pin 10&11 (I get a 1 ohm reading between pins 9 & 10). Besides this potential gun short. Here is the real odd thing. I get no HV when the anode cup is attached to the tube (I do have +/-24v), but I get 19+kv when I pull the anode cup off the tube and measure it with the HV probe. So the HVT is generating the HV, but something is shorted that does allow the tube to work.
Is my tube toast? Will a rejuvenater fix this type of issue? I just picked up a B&K 490 (still waiting for it to arrive) to attempt to fix the blue gun, but have doubts that I can get this tube working with this other HV anode issue.
