TM500 plug-in in an 11k Mainframe
Got a crazy idea of modifying a TM 500 plug-in for use in an 11k Mainframe.The rightmost plug-in compartment of an 11301 could be used only for Trig so the idea
was using a WR501 inside the 11301 for logic triggering.
Actually both the top and bottom rails have the same profile on both plug-in types. Obviously the TM plug-in is shorter and the 7k/11k plug-in is a few mm higher.
The missing length was sawed off from a scrapped 11A32 and rear part of it was used. The plug-in connector came from a 7k blank plug-in board.
On the bottom long M4 screws was used which was screwed into the WR501.
The difference in height.
A pair of special brackets was made ......
.... and used on the top rail.
Mechanically finished and it would slide into the 11k nicely. Off course since the latches are different it was unlatched.
To get access to suitable 11k voltages long pins were soldered in the appropriate holes of the interface board.
I made a circuit board to connect to the pins. I couldn't make the WR501 -4.9V switched supply to start with any 11k voltage so on line I found this little
Positive/Negative Step Down Power Module capable of delivering up to 2A and also change a positive input to negative output to replace the internal
supply. Schematics of the board here.
While operating at its maximum current it got quite hot so a small fan was needed.
The WR501 is packed with a lot of power hungry ECL chips so power consumption turned out to be more than the 11k could deliver especially with two WR probes
attached. So, eventually I had to give up and return the WR501 to original state and use it as it was intended but it was fun trying.
Email me with comments. /Håkan
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