Posts: 292
Threads: 17
Joined: Aug 2010
City: Yorkville IL
I'm going to start off by apologizing if this is a nooby question. All 3 of the bias resistors are blown on this set. The 150k resistor is larger than the 10 and 15, does it need to be a 1 watt or larger? There isn't a notation on the parts breakdown or the schematic. What would cause all three to blow? I found the 80 tube and both of the XXL's weak. I'm replacing all the crumbling wires but the only burn spot on the chassis is where these were located. Any help would be greatly appreciated, I want to make sure it doesn't happen again when I give it a test run. I have a nightmare that it caught on fire the first time I tried it (even with a variac)...
Thanks
Glenn
Happily back in Illinois..not.
Posts: 292
Threads: 17
Joined: Aug 2010
City: Yorkville IL
I posted in the wrong location, sorry lack of sleep.
Ron, if you could move it I would appreciate it.
Happily back in Illinois..not.
Posts: 13,776
Threads: 580
Joined: Sep 2005
City: Ferdinand
State, Province, Country: Indiana
Done.
Excess current usually kills resistors. In your case, you are lucky; this set used individual resistors instead of a multi-tapped Candohm.
Looking at the parts list, it calls for 1/2 watt wirewound resistors to replace the three. I think I would use 1 watt units for the 10 and 15 ohm resistors, and 2 watts for the 150 ohm (note it is 150 ohms, not 150K). I suspect the part number for the 150 ohm resistor, 33-115336 (150 ohm, 1/2 watt, wirewound) is a typo since the actual resistor is larger than the other two.
Oh, and to prevent the new ones from failing, make sure there are no B+ to ground shorts or leakage before applying power.
--
Ron Ramirez
Ferdinand IN
