Rookie mistake! I removed the 4007 and installed a 5817 schottky on the ATX terminals. No dice. Then I thought "I don't see what difference it'll make, but I might as well TRY the diode close to the solenoid". (The soleniod leads are only 24" long.) BINGO! Works like a hot damn! Thanks guys!
rooted thru junk bin and got few 200V poly caps .22uF. ran 2 in para. no dice. ran 2 in para w/ resistors (various). no dice. So, we are all in agreement, the inductive voltage spike is what is causing the board to shut down?
tried with various values of ceramic and electrolitic caps. Changed resistor values too. No change, ATX board shuts down when solenoid de-energizes. Guess next thing is to head down to the store on Tuesday (thanksgiving holiday here on Monday) to buy some faster response caps?
Thanks! I'll try the RC. But why would this work, but not a snubber diode? What do you think is actually causing shut down? Is it the ATX breakout board or is it the power supply? Is it the inductive spike or some sort of RF voodoo?
Using a relay board to power a solenoid that draws .4 amps. Relay board is powered from USB. ATX breakout works fine energizing the solenoid but board powers off when solenoid de-energizes. Tried snubber diode, big electrolitic cap, 14V MOV. I even tried shorting the poly fuse, no dice. Any ideas?