06-23-2011, 11:31 PM
Resistor #48 is the load resistor for the first stage audio amplifier, so if it is bad you'll have a problem with all audio, not just short wave. If the resistor is or was touching something, then it is suspect. Test it with the radio off and unplugged. Put your multimeter leads across it and see what you get. If it is fairly close to 220K ohms, then you are probably OK.
If you have any question about it, then you will get a more reliable test measurement by desoldering either end of the resistor so that end is disconnected from everything else. If you get 220K ohms plus or minus 10% then the resistor is good. Solder it back in place and look for something else.
Chuck suggested some of the other resistor in the AVC circuit, which I think would be 23, 41, and 42. My 42-380 schematic is very blurry.
I'd check out all the resistors if I were you, and replace any that are not within 10%. (Some say 20% is OK, but if it is a 10% resistor as many are, I'll replace any outside of 10%.) Also, you didn't mention changing any wire. The wires in that radio are insulated with rubber, which crumbles over time. My experience with similar radios is that most of the wire should be re-insulated with shrink tubing or replaced. Some of the worst wires in my 42-355s were those on the bottom of the band switch block. A bad wire wire there might give you bad SW.
The insulation should be flexible and soft if you squeeze it. If any is stiff or shows visible cracks it should definitely be replaced. I've seen some radios in which all the rubber insulation is bad and a few with maybe 1/4 good insulation. At best, most of the wires will need replacing or recovering.
If you have any question about it, then you will get a more reliable test measurement by desoldering either end of the resistor so that end is disconnected from everything else. If you get 220K ohms plus or minus 10% then the resistor is good. Solder it back in place and look for something else.
Chuck suggested some of the other resistor in the AVC circuit, which I think would be 23, 41, and 42. My 42-380 schematic is very blurry.
I'd check out all the resistors if I were you, and replace any that are not within 10%. (Some say 20% is OK, but if it is a 10% resistor as many are, I'll replace any outside of 10%.) Also, you didn't mention changing any wire. The wires in that radio are insulated with rubber, which crumbles over time. My experience with similar radios is that most of the wire should be re-insulated with shrink tubing or replaced. Some of the worst wires in my 42-355s were those on the bottom of the band switch block. A bad wire wire there might give you bad SW.
The insulation should be flexible and soft if you squeeze it. If any is stiff or shows visible cracks it should definitely be replaced. I've seen some radios in which all the rubber insulation is bad and a few with maybe 1/4 good insulation. At best, most of the wires will need replacing or recovering.
John Honeycutt
