The Long Way Home

Gentle Reader (and I do mean singular!),

I'm happy to say that the power supply rebuild has all but finished. Let me walk you through the pictures. First, is a picture of the original, unadulterated board.

Notice the large cap in the middle next to the transformer? If it was a can of beans you would have had to throw it out for having expanded beyond it's size. My work was cut out for me.

Replace every electrolytic capacitor and every cement resistor. First job was to remove every single part. Leaving me with a very naked board, like this one.

I removed the two main transistors and their heat sinks so I could take better measurements of the circuit board and the holes underneath.

After removing all the parts, I like to add parts back based on the height of the parts. The smallest parts, or those which are closest to the board go in first, then I move my way vertically. This basically meant that the 22uF capacitors went in first, then the power resistors, and then the big filter caps next to the tranformer.

I know it makes me seem old-school to say this, but I really am amazed at how much smaller and better components are today than they were just 10 years ago. Let me show you the finished board to explain.


Look at just how small the caps are compared to the originals. Also, see those tiny black resistors? Believe it or not, they are 5 Watt Mills non-inductive wirewound. You can't get any quieter than this friends, and they are tiny compared to the cement resistors they replace.

You might notice the canary yellow trim-pots which have suddenly apeared too. These are definitely a nice upgrade. The originals were open, carbon composites. These are sealed conductive plastic trim pots. Smooth as honey, electrically quiet, and have much better long term reliability and stability than the originals. Unfortunately one thing I did find when I put everything back together is that the 5V outputs were far too low, which I think is due to a bad transistor. Not a huge deal, but it means the tuner won't be put back together this weekend.