Hey Guys, I built this amp kit about 10yrs ago and it has changed owners about 5yrs ago. The new owner says he had finished the 1st set, after break he flips off standby and the pilot light goes out and amps is dead. Installs new fuse, fuse blows right away. On the bench I find the PT HT secondaries shorted. The 5v and 6.3 secondaries read normal ohms. Checked rectifier tube and socket OK, no signs external shorts and the 5U4GB works well in another amp. All filter caps test good with the ESR meter, no signs of external shorts, leaking or blisters. All resistors through out the amp are within spec. except one of the two (schematic lists one 10w R for all four power tubes. I used one 5w R/pair instead) 5w 470R power tube cathode bias resistors had burnt open. I checked all four 6V6`s for shorts and tried them in my Champ type amp one at a time. They all played well and read within 1.5mA of each other. Tested for shorts in the power tubes sockets OK. Im trying to determine what blew the PT and only one power tube cathode resistor. Did they both fail at the same time? While doing tests through out the amp I did fine that the 6.3 htr circuit was shorting to ground through the pilot light. Took the bulb out and reinstalled it short was gone. You would think that short would have taken out the 6.3v secondaries??. Another thing I found when I removed the 5U4GB rectifier the guide pin was broken off the base and a white mark placed on the tube base where the tab should be. Perhaps the new owner is not telling me the whole story? Maybe he remove it and installed it incorrectly? Any ideas or thoughts are much appreciated. Thanks in advance.. Punky
Topic: Weber 5E3x2 on the bench (Read 2272 times)