GE Corometrics 126, Service Manual

Page: 304 / 440

10-6 120 Series Maternal/Fetal Monitor Revision B
2015590-001
Strip Chart Recorder Servicing: Field Serviceable Assemblies
Printhead Adjustments
Refer to Figure 10-1 and Figure 10-2 for identification of the adjustment points
outlined in this section, and to assist in clarifying adjustment procedures. Figure 10-
1 and Figure 10-2 show top and right side views of the 120 Series Monitor strip
chart recorder assembly removed from the unit’s chassis.
Table 10-1 gives a description of each recorder adjustment. Adjustments C through
F can be performed without removing recorder from unit’s chassis; however, they
require removing the monitor’s top cover.
The printhead may require performing one or both of the following offset
adjustment procedures.
Vertical Offset Adjustment
To check vertical offset alignment, run at least two monitor self-tests by depressing
the front panel
Test pushbutton. The first horizontal trace should be printed 0.490 ±
0.002 inch from the right hand paper guide. (Refer to Figure 10-3 .) Perform the
following steps if the trace does not fall within the specified offset range.
1. Loosen the two set screws labeled A in Figure 10-1 .
2. Adjust hex-head screw labeled C in Figure 10-2 , until test trace falls within
specified tolerance.
3. Tighten the two set screws labeled A .
Horizontal Offset Adjustment
Adjust the horizontal offset if any of the following symptoms are detected. If
skewing occurs, check for other malfunctions. Noticeable skewing of a vertical line
printed on the strip chart paper is usually accompanied by one of the following
symptoms:
„ Paper consistently curls to one side.
„
Printing of unequal weight occurs along the vertical trace line, from one end to
the other.
„ Dots are missing along the vertical trace.
„
Printing is too light following printhead replacement.
If the Horizontal Offset Adjustment is required, perform the following steps:
1. Loosen the four hex-head lock screws—two on each side. The right side screws
are labeled
B in Figure 10-2 .
2. To move the printhead forward on one side, back-off the corresponding captive
screw (turn counterclockwise) from its alignment block. To move the printhead
backward on one side, tighten the corresponding captive screw (turn
clockwise).
3. After making the necessary adjustments, tighten the four hex-head lock screws
labeled
B .