Service manual

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[TITLE]
OCTOBER 27, 2000
[PART NUMBER]
PX-600 Field Repair Guide Page 6
check perameters of control system.
Does it have functions for timed
operations?
MRX tuner has little or no
reception.
Is the antenna connected?
Powered Antenna?
Check for Proper tuner set up.
Connect antenna.
Make sure powered unit is supplied with the correct
voltage (AC or DC).
US frequencies should be set at .2MHz.
Front Panel “talk back”
LED lit or blinking – no
intentional input.
Is there an extra ordinary amount of
light shining on the front panel?
Use programmer screen to check
status identifiers:
I = Front Panel is receiving IR.
K = Information from A keypad is
being received at head unit. Either a
button press or receiving IR.
P = head unit is send IR to sources.
Front panels – PX-600 use a pigtailed 1/8” mono jack
and plug it into the IR input on the back panel. MRX
use a piece of Black tape to cover the IR receiver.
Front Panel LCD (MRX)
has no font
LCD intensity potentiometer needs
adjustment.
Remove the top cover of the MRX and find the small
hole direct behind and to the right of the LCD screen.
Use a small #1 blade screwdriver to gently move the
potentiometer till the font is visible on the LCD screen.
Front Panel LCD (MRX)
has no back light or is
split
Check ribbon connections to front
panel.
Make sure there is a complete connection and there
are no shorted wires. .
Programmer LCD (PX-
600) has no font
LCD intensity potentiometer needs
adjustment.
Remove the top cover of the programmer and find the
only potentiometer on this circuit. Use a small #1
blade screwdriver to gently move the potentiometer till
the font is visible on the LCD screen.
Programmer LCD (PX-
600) has no back light or
is split
Check ribbon connections to front
panel
Make sure there is a complete connection and there
are no shorted wires or broken connectors.
Characters remain on
LCD after back light goes
off.
After PX-connect or MRX-connect
this is normal.
If this happens at any other time call Customer
support.
Tuner frequency
displayed on LCD (MRX)
does not match station
being listed to.
Check that tuner set up is set for US
standards.
US frequencies should be set at .2MHz.
Use tuner preset button 1 and MUTE to activate main
menu.
PX-600 or MRX
constantly resets.
Remove keypads. If the problem still
exists then it is an RS-485
Transceiver failure.
If the problem stops then
Change RS-485 Transceiver.
Put one Keypad on the data bus at a time until the
bad keypad is found. Replace KPS processor board
or entire keypad.
MRX Overheats Does the fan run?
Is the unit installed in cabinet w/no
ventilation?
Remove cover and find the power wire to the fan. Use
a multi meter to see if the fan’s windings are still in
tact. NO- replace fan.
Ventilate cabinet.
PX-600 Overheats Is the unit installed in cabinet w/no
ventilation?
Ventilate cabinet.