Zagadka's Site

It's now burned permanently into my brain!

Pull R9, R10, R11. Break the trace from pin 6 to the +10V rail. Repace R10 with a 3.3KR 1/4W Carbon Film Resistor. Replace R11 with a 33 microfarad 35 volt electrolytic capacitor with negative facing the SCR. Turn the board over. Scrape the broken pin 6 trace on the pin 6 side. Solder a 15V Zener Diode from pin6 trace to ground. Solder a 1n4148 signal diode from pin3 to pin 6. Add a 680p ceramic cap in parallel with C2 on the back of the board. Run a 330K 1/4W Metal Film Resistor in heatshrink from pin 6 to active after the fuse.
Fit the power cord, socket and mounting block. done.

I modified 16 boards in this way - it doesn't seem like it'd take so long. It took me a little over 8 hours. It is delicate work though and must be done accurately or the board will toast it's self. Something different. I did enjoy it - even though I was stuffed after 8 hours of soldering and assembly =)