3
SERVICE INSTRUCTIONS
For radios that require an open circuit when the microphone is
on-hook (such as many Ericsson/GE models), the hang-up logic
can be reversed by the following procedure.
1. Open the microphone case by removing three retaining
screws.
2. Carefully separate the case halves, taking care not to lose the
rubber pieces associated with the cartridge assembly.
3. Add the following components to the PC board assembly at
the locations indicated by the highlighted parts in the
dash-line parts in Figure 5 and photo in Figure 6.
•
NPN Transistor Q2 (Shure Part No. 86A350; Motorola
2N5210)
•
Resistor R5, 56 k
Ω,
1
/
4
W (Shure Part No. 45LA563C)
4. Unsolder and move the blue wire from W5 to W4.
CIRCUIT DIAGRAM
FIGURE 5
CARTRIDGE
W2
W3
WHT
SP1
86B434R
W1
GND
R1
10K
C1
120pF
120pF
120pF
C2
.001µF
.001µF
.018µF
.001µF
10µF
C5
C6
R3
27K
R2
68K
C7
C4
C3
3
2
1
Q1
86A350
R4
470
R6
51
C8 +
YEL
W6
W7
BLK
86A434
SP2
HANG-UP BUTTON
W4
BLU
W8
W5
JUMPER
(INSTALLED)
J1
1
2
3
4
5
6
AUDIO OUT/DC BIAS
PTT HI
HANGUP
PTT LO
N/C
GND
