Fisher Scientific Model 14 Lab Oven Fix

 

 

Relay: RM 805615

SSR: 70s2-03-c-25-s

Door Interlock Switch: Original wiring normally closed with door open.  Door closed is switch open.  Second contact is normally open – door closed == switch closed.

  

 

Research Links

• Relay: RM 805615
• SSR: 70s2-03-c-25-s
• Standard DIN Sizes of Panel Mounted DIN Temperature Controllers

Notes:

• Display hole is set up to be compatible with 1/8 DIN   – 1/8 DIN 3.64×1.780 inches Long dimension vertical or horizontal
• Thermocouple: Red / Yellow –> K type

Fix / Re-Engineering Notes

• Display hole in Fisher 14 is 1/8 DIN standard size – thus standard sized temperature controllers will slide in with no physical modification.
• Replace factory temperature controller with an XMT634. 
• Replaced N type thermocouple with K thermcouple because XMT634 does not run with N type.  
• No relay in XMT 634 therefore modified to use the door switch second contact so that the main relay will de-energize the coils when the door is open.  Door closed energizes the drive circuit and allows running.

Operation

• PDF: XMT634 / Set64RS operating instructions