11-10-2016, 03:59 PM
I feel like I'm in a new world here. This will be the first time I've tried to fix an AA5. All my previous repairs have been transformer sets or 20s TRFs. I have recapped this one and changed out any resistors that needed it. I used my ohm meter to see if the filament string has continuity, and it does...that is if measuring from pin 2 on the 35Z5GT through pin 8 on the 14B6. When I apply power, the pilot light comes on and after warmup the speaker makes noise, but the noise is hum between strong stations, squeaks on signal (and the pilot light dims a bit), and some minor crackling as I tune across the dial.
I have made a mistake with the loop antenna I'm pretty sure. I disconnected it without labeling the leads (it has four-two to the antenna coil and two to the tuning capacitor. So I'm not sure if I have that connected correctly...I went by the drawing of the antenna on the schematic as well as I could. How crucial is the hookup on the loop?
Also, I used 33uf electrolytic caps at 250v for all three electrolytic caps because I had them here already...that should be OK, right?
I've read these sets get silver mica disease, but I would hear crackling all the time if that was the case, and I would have some stations behind the noise as well. Basically, it looks to me like the radio is responding to signal (judging by the different noises and the pilot light getting dimmer at certain spots on the dial), but isn't converting signal to output for some reason. Any ideas?
I will in the meantime start tracing the problem on the schematic. Is troubleshooting the same as with transformer sets? Start at the output and work backwards? If so, output is likely good since I hear noise and volume is acceptable. So check the detector next, then IF, then the converter.
I have made a mistake with the loop antenna I'm pretty sure. I disconnected it without labeling the leads (it has four-two to the antenna coil and two to the tuning capacitor. So I'm not sure if I have that connected correctly...I went by the drawing of the antenna on the schematic as well as I could. How crucial is the hookup on the loop?
Also, I used 33uf electrolytic caps at 250v for all three electrolytic caps because I had them here already...that should be OK, right?
I've read these sets get silver mica disease, but I would hear crackling all the time if that was the case, and I would have some stations behind the noise as well. Basically, it looks to me like the radio is responding to signal (judging by the different noises and the pilot light getting dimmer at certain spots on the dial), but isn't converting signal to output for some reason. Any ideas?
I will in the meantime start tracing the problem on the schematic. Is troubleshooting the same as with transformer sets? Start at the output and work backwards? If so, output is likely good since I hear noise and volume is acceptable. So check the detector next, then IF, then the converter.