Does anyone here have a schematic diagram over a vintage LakeShore 330 temperature controller, or could otherwise tell me what component Q6 used to be?
I "fixed" the controller last week, where an OPA541 power opamp had blown out its magic smoke and it worked again for a couple of days, just to then burn up a TO-220 device on the same heatsink. Of the type number only the last two digits remain legible: ...15
Since its right leg was connected to the positive rail of the power opamp and since all other TO-220 parts inside are voltage regulators (plenty of them) I falsely assumed it must have been a 7815 - in the hindsight quite clear that it could not have been...
![Face Palm :palm:](https://www.eevblog.com/forum/Smileys/default/xfacepalm.gif.pagespeed.ic.EBDwh1hCfo.png)
- but I was proven wrong by a small explosion...
![Broken! :-BROKE](https://www.eevblog.com/forum/Smileys/default/smiliey_scope_broke.gif)