HP 2113B service manual / schematics

[Peter Brown]

Hi All,

I'm in the process of powering up a 2113B.  I took a look at the output 
voltages from the PSU and they all look fine *except* the -2 volt line that 
appears to be running at -2.47 volts.

I have the 2109B / 2113B installation and service manual but the service 
procedure just talks about adjusting the 5 volt line and all the other 
supply voltages tracking this one.

I can't find a schematic for the power supply in the documentation that I 
have 02109-90015.

Questions:

1.  Is my copy of 02109-9005 (Installation and service manual) incomplete 
i.e. should there be a schematic in it?
2. Does anyone have a schematic for the 2019B / 2113B computer power supply. 
  Note that the 'B' is important as the power supply was revised between the 
'A' and 'B' models.
3.  What is the -2 volt line used for?
4.  Does it matter that the -2 volt line is outside specification?
5.  Is a full schematic available for the 2113B computer? -  I'm sort of 
interested in what exactly is going on on the motherboard.

Many thanks

Peter Brown