400A's on/off flip flop flipping and flopping.

[ALLEYGATOR]

Is there anyone left out there who can help me in troubleshooting one of the first Threshold 400A's??? I have one that's turning itself on and off repeatedly. According to a thread from Nelson Pass, this circuit uses an on/off flip flop made with an op amp that uses positive feedback. The on and off LED's blink back and forth on the front panel like a RR crossing gate switching the main power supply's Triac on and off ... 🙁

THANKING YOU IN ADVANCE,

Frank DuVall
(ALLEY GATOR)

 

[Nelson Pass]

400a's had a front panel switch.

😎