[ARC5] Dead BC-348-R

JAMES FALLS radio-tuber at att.net
Tue Aug 9 21:06:01 EDT 2022


My BC-348-R is dead after a year of quiet. The dyno sounds like I remember it, not lugging down. I started with capacitors. 

I was last inside it 10 years ago, got everything happy and aligned. I replaced a bunch of caps and resistors at that time. Now, all the remaining 0.1uF paper canned caps (48-2/3, 49-2/3/4) are very leaky. I will replace them as the others. 

This time, I found resistor 57-5 (4.7k) fried between the 1st IF (6K7) tube and the 2nd IF xfmr. So, from the schematic, it looked like B+ was being shunted thru mica capacitor 11-9 (.01) to ground. I lifted one end to test, and it’s OK. No leakage on my cap checker, infinite resistance on my VTVM. 

All tubes good to excellent. 

My question is what else would make this resistor burn up so all I can see is the first yellow stripe? 

I’m at a loss, so I’m asking the MilSurp Wizards for help on this. Any ideas?

Jim Falls K6FWT 


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