LakeShore 330 temperature controller

[uwezi]

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... - but I was proven wrong by a small explosion... 

[tautech]

7915, negative reg, not positive reg 7815 ?

Grab the datasheet for both, check the pinouts and typical application schematics.

Sometimes a pic of both sides of the PCB can help us......

[uwezi]

7915, negative reg, not positive reg 7815 ?

Sometimes a pic of both sides of the PCB can help us......

I thought of the 7915 as well, but it does not make sense either at this position. Also as I saw later all 78xx and 79xx are labeled as Uxx on the board (as they should), while the burned part was Q6. I suppose it might have been a MOSFET like an "...N15" or "...P15"

[uwezi]

Let me rephrase my question:

After a more detailed analysis of the traces and connections around the burned Q6:

Is/Was there a power NPN transistor around in the mid-1990s:

• TO-220 package BCE
• part number ending in 15
• VCEmax > 60V

I am now quite sure that the transistor was part of a discrete voltage regulator with two zener diodes as references (1N5363 alone and 1N5363+1N5360 in series). The switching between the two ranges was done through a relay which also switched between two taps on the mains transformer.

[Kleinstein]

The BCE pinout it the normal one for TO220 transistors. So plenty of transistors to choose from.

For the BD series, there are some types with subtypes of -40 / -25 and -15. There might also be 2Nxx15 or 2SCxx15.

[little.tesla]

Hi,

sorry for resurrecting this thread.

Did maybe somebody in the meantime find a schematic of this device or did dump it's firmware?

[khach]

Schematic diagramm

[zrq]

I got hands on a Lakeshore 330 in the exactly same condition. Q6 was cut and removed by the previous owner and the OPA541 exploded. If anyone needs a memory dump, drop a message and maybe I can help.