Questions on Agilent DC Power Supply Schematic with CC

[waht]

This is an Agilent DC power supply schematic with CC. I've been going over it and got a few questions.

What is the purpose of 2 diodes CR10 CR11 in the current error amplifier and how is the current amplifier suppose to measure voltage across R2? Why do we need R34 ?

Also what does JP1 and JP2 do?

 

[Averagesupernova]

I would say that the diodes are to prevent too much voltage from developing across the input of the op-amp. The current through R2 (voltage across it) is sensed by the bridge circuit formed by R27 and R34 (one side) and R18 and R17 (other side). Somehow, through J1 (3) V+ there must be a connection back to +S. I don't see it on the schematic though. But it must be present in order for U4B to develop an input voltage. It may not be a direct connection, but there must be something that relates them.

 

[waht]

Well, the V+ V- and I+ I- are high impedance digital voltmeters. One to measure voltage across the output and the other was suppose to display current by measuring voltage across R2.

The weird aspect of this schematic is the positive output terminal is basically a ground with respect to the bias supply S+ .