816173-821 Frame/Panel Simple Tests

©Brooke Clarke, N6GCE

General Information

This frame panel assembly is used on the PRC-126, PRC-128 and PRC-136 radios.  By showing the label as a separate line item the frame panel assembly part number does not change for the three different receiver-transmitters.  It is also very similar to the frame panel assembly used on the PRC-68B and less so the PRC-68A.

Test Conditions

Remove both modules and test just the frame/panel assembly.  It's handy to have a micro test clip on one or both test prods to grab onto the pins on J2 and J3.

See Figure 5-7 for component location and pin numbering.  Note that J2 and J3 show op on both sides of the frame panel back bone, but with different pins sticking up.  Pin 1 on these connectors is near the center top when looking at either side.  All the odd numbered pins are on the top row and even numbers on the bottom row.  Since you are seeing the same connector on both sides the right to left order reverses depending on which side you are looking at.

See the 816173-821 Frame/Panel Schematic (1/2 MB A size pdf) to clarify what's being tested.  This has BOLD lines for ground, gray for TTL logic and some colors used to make understanding somewhat easier.

A Fluke model 87 was used for the following measurements.  It uses 1.0 mA in the diode mode.  Using resistance to check diodes gives different results on different meters because of different test currents.  The 1 mA forward voltage drop also is a very good indicator of the diode type.

Table

 
 
 
Item
Position
Mode
From/Blk
To/Red
Indication
Comment
 1
DC Power
VOL/OFF
On
Diode
J2-12
Batt +
0.20 Volts
CR1 fwd & S2 on
 2
 
VOL/OFF
Off
"
J2-12
Batt +
OL (Over Load = open)
S2 off
 3
 
VOL/OFF
On
"
J2-12
AUDIO-E
0.20
CR2 fwd & S2 on
 4
 
 
 
"
Gnd
J2-11
chassis frame
control panel
Batt -
0.00
 
 5
SVM Jmp Plug
 
 Plug Installed
 Ohms
J2-18 
J2-20 
< 1 Ohms
Tx Jmp 
 6
 
 
Plug Installed
 "
J2-5 
J2-28 
< 1 
Rx Jmp 
 7
 
 
 
 
J1-1
J2-18
< 1 
 
 8
 
 
 
 
J1-2, 10, 13
Gnd
< 1 
 
 9
 
 
 
 
J1-3
J2-4
< 1 
 
 10
 
 
 
 
J1-4
J2-28
< 1 
 
 11
 
 
 
 
J1-5
J2-5
< 1 
 
 12
 
 
 
 
J1-6
J2-7
< 1 
 
 13
 
 
 
 
J1-7
J2-23
< 1 
 
 14
 
 
 
 
J1-8
J2-3
< 1 
 
 15
 
 
 
 
J1-9
J2-20
< 1 
 
 16
 
 
 
 
J1-11
J2-12
< 1 
 
 17
 
 
 
 
J1-12
J2-10
< 1 
 
 18
 
 
 
 
J1-14
J2-22
< 1 
 
 19
 
 
 
 
J1-15
Batt +
< 1 
 
 20
SPKR/MIC 
 
 
Ohms 
 Gnd
J2-25 
17 - 27 
 
 21
 
 
 
Diode
Gnd
J2-25
0.02
hear weak click
 22
Controls
SQ DSBL 
 Press
Ohms
Gnd
 J2-23
< 1 
 
 23
 
INCR 
Press
Gnd 
J2-1 
< 1 
 
 24
 
 SET
 Press
Gnd 
J2-2 
< 1 
 
 25
 
 PUSH
TO
TALK
 Press
 "
Gnd 
J2-27 
< 1 
 
 26
 
 ANT
A
 "
 J3-17
J3-11 
1.2 k - 1.8 k 
Logic 
 27
 
 
 B
 "
 "
 J3-9
 1.2 k - 1.8 k 
 "
 28
 
 
 C
 "
 "
 J3-7
 1.2 k - 1.8 k 
 "
 29
 
 
 D
 "
 "
 J3-5
 1.2 k - 1.8 k 
 "
 30
 
 
 E
 "
 "
 J3-3
 1.2 k - 1.8 k 
 "
 31
 
 
 50
 "
 "
 J3-13
 1.2 k - 1.8 k 
 "
 32
 
 
 
 
 ANT
 J3-16
8 K - 12 k 
 "
 33
 
 
 A
Cap
 "
J3-11
5 nF 
 RF
 34
 
 
 B
 "
 "
J3-9
"
 "
 35
 
 
 C
 "
 "
J3-7
 "
 "
 36
 
 
 D
 "
 "
J3-5
 "
 "
 37
 
 
 E
 "
 "
 J3-3
 "
 "
 38
 
 
 50
 "
 "
 J3-13
 "
 "
 39
 
 
 
 "
 "
 Gnd
0.01 uF 
 "
 40
 
 CHAN
 1
Ohms 
J3-8 
J3-11 
< 1
 Logic
 41
 
 
 2
 "
 "
 J3-9
 < 1
 "
 42
 
 
 3
 "
 "
 J3-7
 < 1
 "
 43
 
 
 4
 "
 "
 J3-3
 < 1
 "
 44
 
 
 5
 "
 "
 J3-5
 < 1
 "
 45
 
 
 6
 "
 J3-4
 J3-5
 < 1
 "
 46
 
 
 7
 "
 "
 J3-3
 < 1
 "
 47
 
 
 8
 "
 "
 J3-7
 < 1
 "
 48
 
 
 9
 "
 "
 J3-9
 < 1
 "
 49
 
 
 10
 "
 "
J3-11 
 < 1
 "
 50
 
VOL 
 
 "
 Gnd
J2-26 
70 k - 130 k 
 audio
 51
 
 
OFF 
 "
 "
J2-24 
< 100 
 "
 52
 
 
 Full CW
J2-26
< 20 k
 "
 52
Display
 LCD
 
 Diode
Gnd 
J3-15 
1.80 
Back Light 
 54
 
 
 
"
J3-12
Gnd
0.56
+5 pwr
 55
 
 
 
Ohms
J3-6
Gnd
open
data
 56
 
 
 
"
J3-10
Gnd
open
clock
 57
Connector
AUDIO
 
Ohms
pin A
Gnd
< 1
Gnd
 58
 
 
 
"
pin B
J2-17
< 1
ext spkr
 59
 
 
 
"
pin C
J2-19
< 1
PTT
 60
 
 
 
"
pin D
J2-21
< 1
MIC
 61
 
VOL/OFF
On
Diode
J2-12
pin E
0.20 Volts
CR2 fwd & S2 on
 62
 
 
 
"
pin F
J3-14
< 1
Ext Data
 

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[an error occurred while processing this directive] page created 6 July 2001.