2017-11-04 Zenith Royal 500 Fixed Part Way

I got another Zenith Royal 500 at auction, I think it was $20 but the shipping cost a lot.  I got it out and tried it out.  I found the battery contacts were in good condition.  The battery compartment was missing the cover.  It came with a leather case, so that will stop the batteries from falling out.

The audio was very weak, so I knew that the capacitors were bad.  I jumpered the 5 uF from the volume control wiper to the driver transistor with a 4.7 uF and the volume increased dramatically.  So I soldered the 4.7 across the bad capacitor – there was plenty of room behind the PC board.  The other capacitors seem to be okay.

Now I found that the stations sounded distorted.  Apparently someone tried to adjust the IF cans and made things worse.  This seems to be the problem with many of these old radios.  People who have no knowledge of electronics try to fix something and they have no idea that what they’re doing is worse than leaving it alone.  So I did a bit of adjustments to help.  I need to get a signal generator and do a proper alignment.

The other problem is the volume control is intermittent and noisy.  It’s worn and needs cleaning.  Considering these radios are over fifty years old, that is to be expected.  I’ll have to clean it with contact cleaner.

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