(2) Select a probable cause (column 2). You suspect the problem is caused
by an excessive current draw (number 1).
(3) Troubleshoot (checking procedure - column 3). You check to see if the
unit is putting out a constant 540ma current draw. You refer to the charging circuitry for
the monitor in Appendix E (D-23). First you unsolder the anode CR36 from the circuit
board and place an ma meter in series between the anode and where it normally sits on
the board. Then you plug the unit into a known good ac outlet. You expect to see 540ma
on the meter, but you do not. After unplugging the unit and re-soldering the CR36 anode,
you refer back to the Probable Cause column to select another probable cause.
(4) Select a probable cause (column 1). You suspect the problem is in the
(5) Troubleshoot (checking procedure - column 3). Using the volt meter,
which is referenced to a ground, you plug the unit into an ac outlet. You read a +12vdc on
the cathode of CR35 indicating CR35 is good. Following the circuit, you read the same
voltage on the anode of CR34, but 0v at the cathode of CR34. This indicates that CR34 is
open. Therefore the problem is CR34.
(6) Determine corrective action (column 3). You should replace the faulty
Section II. REMOVE AND REPLACE DEFECTIVE MODULES
Once you have isolated a malfunctioning module, you repair or replace the
module. Field repairs are usually limited to replacing worn or damaged parts. Use the
following procedures when removing and replacing defective modules of the MRL Porta
DISASSEMBLE THE MONITOR
Follow the procedures for accessing the main circuit board in lesson 1, paragraph
1-3. Use the following procedures to remove the major components. When you have
repaired or replaced the defective module, reassemble it by reversing the disassembly
a. Remove the Monitor Main Circuit Board.
Disconnect the following five cables:
Monitor cable assembly.