Heathkit SB-221 high voltage arc

Replaced the rectifier/metering board
Worked fine for about a week and developed this issue

[@scott65disel]

That sounds vicious

[@macp8854]

Once there is an arc on a PC board and the board is burned, that burn is carbon and is now a resistor. Each time it arcs, resistance is lowered until it don't go boom no more.

[@heavydiesel]

Ouch!

[@slamdvw]

What's the rest of your station consist of?

[@gliderp]

With the top cover off, the HV interlock is doing it's job shorting the B+ to ground. 'Least that's what it looks like.

[@sirmordrede]

yeah he needed to put the lid on so it down ground the high voltage

[@macp8854]

You should know that EVERY time an arc burns a circuit board it turns the material into carbon, yes just like a resistor. EVERY time you cause it to arc again, YOU are lowering the resistance by adding more carbon. Like doing the same thing 100 times expecting a different result.

[@Dantana510]

Hi, I have some Quincy's Sullair & Scale air vacuum pumps that I'm trying to sell do you know of anyone ?