Your -2 supply sounds just fine.
This supply voltage is used to terminate the I/O backplane, making the
bus signal levels compatible with the original HP 2116, which used CTL
logic. The 2113's processor uses modern TTL, with special drivers for
backwards compatibility of the I/O bus.
As to the power supply, there are about 20 different revisions, some with
battery backup, some without.
I think the schematics are on Al's web site for the processor. I'm less
sure about the power supplies.
----- Original Message -----
From: "Peter Brown" <peterbrown10(a)hotmail.com>
To: <cctalk(a)classiccmp.org>
Sent: Monday, November 15, 2004 2:17 PM
Subject: HP 2113B service manual / schematics
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