Texas Instruments 880 - Screws; Signal Ground;Protection Ground Jumper Plug

0.5 CHANGING SIGNAL GROUND /
PROTECTION GROUND
WARNING
Disconnect the power cable before
removing the cover! Failure to
remove the power cable will result
in a serious shock hazard. Chang-
ing the signal ground/protection
ground jumper should only be done
by a qualified technical person.
The Model 880 Printer is normally assembled with
protection ground and signal ground connected
by a jumper
plug between E4 and E5 on the Moth-
erboard.
When a system needs the
signal-chassis ground
to be isolated, remove the jumper plug between
E4 and E5 and place it between E4 and E3 for
storage.
If you are not sure which configuration to use,
measure the resistance between pins
1 and 7 of
00
@
D
E3
E4 .
E5 .
the serial data cable with the cable connected to
the system. If an open circuit is measured, the
jumper
plug must be installed between E4 and E5.
If a short circuit is measured, the jumper plug
between E4 and E5 must be removed and installed
between
E4 and E3 for storage. Refer to Figures
0-2and 0-3.
OVERHEAD VIEW
GROUND JUMPER
PLUG LOCATION
SCREWS
SCREWS
- .r--
---,1
2222627-38
Figure 0-2. Locations of Printer
Cover Screws
2222627-39
Figure 0-3. Signal Ground/Protection Ground Jumper Plug
0-3