Subject: TM-732A - Control PC Board B+ Foil Damage
Date: March 28, 1994
Symptom: Unable to turn on the power. No DISPLAY illumination, radio does
not function.
Countermeasure: The B+ circuit foil path near connector CN403 of the
CONTROL Unit is burned open. This symptom can occur when the front panel
is unplugged from the main chassis while the power is still turned on.
Adding a resistor in series with the "B" line will help to limit current
flow and prevent/limit this symptom from occurring.
Parts Required:
Qty
Description
New Part No.
Circuit Description
1
4.7 ohm chip resistor
R92-1281-05
R290
Procedure:
On the TX-RX Unit (X57-4000-xx/B4) cut the PC Board trace from the "B"
line on CN203 that goes to the DC 13.8 Volt line. Install the 4.7 ohm
resistor across this cut.
Caution:
This modification requires soldering equipment rated for CMOS type circuits. It also requires familiarity with surface mount soldering techniques. If you do not have the proper equipment or knowledge do not attempt this modification yourself. Seek qualified assistance.
Time required for this modification is 60 minutes or less.