Keithley 2400 spark followed by smoke...

[Joe e19]

Hello

I have a Keithley 2400 SMU that produced a spark from a probe and now doesn’t read anything sensible, reading 23v without anything connected. The probes were not currently measuring or under any load at the time, just being moved to connect to a photovoltaic device. It seems something has blown inside the unit however it still turns on fine without displaying any error message. I'd like to repair the unit as it still seems to function. Any ideas what I could try next for troubleshooting?

[plesa]

Check all FET and BJT mounted on heatsink. I assume one of them is dead at least. Check the current sources and zener diodes around.
In one of the user manual is simplified shematic. Or look for H class amplifier.
http://www.google.com/patents/US20130265110
Complete self test passed?

[Joe e19]

Thanks for the replies. The unit passed it's self tests fine, it's currently in someone else's hands will update if they fix it