|
You mentioned testing the tubes , and also substituting . Did your test include a check for Heater to Cathode short , especially on the 50L6 ? If all your checking is Cathode emission , and your pool of substitutes only includes a couple of each type , the possibility exists that more than one of your 50L6 tubes could have this defect (It's a somewhat common failure mode in the 50L6 type) .
|