12 Jun
2020
12 Jun
'20
7:02 a.m.
On 6/9/20 7:13 PM, Glen Slick via cctalk wrote:
On Tue, Jun 9, 2020 at 3:10 PM Bill Gunshannon via
cctalk
<cctalk at classiccmp.org> wrote:
Sorry for the delay. Since the lockdown started Verizon DSL has
been a total disaster and I frequently go for days without any
connectivity.
As for the subject under discussion. You are right mine did have
a metal cover over it with the voltages, (but not the pinouts!)
It's been so long since I tore it apart to fix that I had forgotten
and had to dig the box out that has everything but the PSU Circuit
Board in it to refresh my memory. Things having changed so much
since then I am going to take another shot at fixing the original
PSU before replacing it with something non-DEC. But, based on the
voltages used, building a replacement from scratch would be
relatively trivial.
bill
On 6/9/20 2:51 PM, Glen Slick via cctalk wrote:
(I was going to change the subject line for this reply to reflect the
VXT-2000 discussion but maybe it is already too late to do that
without making message threading even worse?)
Does your VXT-2000 look significantly different than the images on
this page? Is the power supply in your VXT-2000 a bare board that is
not fully enclosed?
https://terminals-wiki.org/wiki/index.php/DEC_VXT2000
The power supply in my VXT-2000 matches the fully enclosed H7109-B
power supply as shown in this image:
https://terminals-wiki.org/wiki/images/b/bb/DEC_VXT2000_111543249570-2.jpg
On Tue, Jun 9, 2020 at 9:04 AM Bill Gunshannon
via cctalk
<cctalk at classiccmp.org> wrote:
Thank you for that. Mine has no labels or anything. It is PC Board
with Digital, Side 1, Side 2 and a number I don't recognize on it.
I guess the -9V is the only odd one but you could easily get that
from a -12V line. I may get to fix it yet.
bill
I have a VXT-2000. It is broke. If I could find out what the voltage
and current requirements were and their positions on the power connector
I would replace it in a heartbeat.
For the VXT-2000 with an H7109-B the rated voltage and current values
are printed right on the power supply label:
+5.1V, 7.81A
+12.1V, 0.62A
-12.1V, 0.46A
-9V, 0.2A
Fixed width character pinout diagram:
+=================+
-9V | Yellow | Orange | +12.1V
+--------+--------+
??? | White | Black | Gnd
+--------+--------+
+5.1V | Red | Blue | -12.1V
+--------+--------+
+5.1V | Red | Black | Gnd
+--------+--------+
Gnd | Black | Black | Gnd
+=================+
The mystery is the White wire. The power supply label only lists 4
output voltages. The White wire appears to be routed to the Ethernet
daughter board. The measured voltage appears that it might be floating
slightly negative, somewhere around -1.5V when the Ethernet daughter
board is installed and around -5V when it is removed. Maybe it is a
high impedance earth ground connection? It appears to be connected to
the shield of the Ethernet BNC, which measures around 1M-Ohm to the
chassis ground when the power supply is disconnected from the main
board, and around 0.75M-Ohm when the power supply is connected.
