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Do you have the radio itself working? If so, have you measured the current draw at 4 volts? The original solar array drops to around 3 volts at 12ma of current draw, so minimizing current draw is an absolute must in order to get these things to run from the solar array.
After you replace the 5 electrolytics, you'll probably have to replace R14, R15, R16, R17 and R21. Although it doesn't say anything about this in the Sam's, I believe some of these resistors, if not all 5 were hand-picked or at least sorted at the factory prior to assembly. This is/was necessary to get the operating current down to 7.5ma no signal/minimum volume, 10 ma with signal/normal listening volume. All 5 of these resistors work together to set up the bias of the 2 2N185 push-pull output transistors.
Every one of these sets that I have worked on have required the replacement of these resistors. If you simply replace the electrolytics, you'll probably find that the operating current is a flat 16 to 19 ma., with more than 85% of that due to current draw by the audio output stage due to incorrect biasing. On batteries or a power supply, it will function perfectly that way! But it will NEVER run from the solar array with that much current draw. A quick test to see if the bias is correct is to measure the voltage drop across R20. It should be around .038 to .04 volts at normal listening levels.
Fun fact: Minus the audio output stage, this set draws less than 2.5 ma, including the audio driver stage! That's less than 1/100th of a watt! Not bad for 1958 technology!
I know that this doesn't help you with your search for a replacement solar array, but when you get to that point, it may keep you from pulling your hair out!
Good luck,
Matt
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