This is another Icom IC-746 Pro with a failed display backlight. Its a very common problem in these rigs, one of its few flaws. The NPN transistor that regulates this, is very small and surface mounted, using a very tiny area of the copper backplane of the pcb as the heatsink. I remove the device, install a larger device on the metal enclosure for the inverter, and wire that back to the circuit. Not complex, but somewhat time consuming. Here's a vid and a few pics...
This is another Icom IC-746 Pro. This unit had a failed backlight in the display, a problem with the automatic antenna tuner, and no audio from the external speaker port.
The backlight problem is fairly common. The pass transistor for the CCFL supply has inadequate heatsinking, and fails eventually. I installed a larger device, and heat sinked it to the CCFL supply enclosure for better cooling.
The tuner was also a common problem. The little stepper motors fail that turn the air variable caps in the tuner. The 746 & 756's use the same motors. I found a source via adafruit for Arduino projects, for the same exact motors. This one got new motors, and was up and running.
Lastly, the lack of audio from the rear ext speaker port was tracked down to a small damaged pc trace at the jack. I bridged the damage, and all was well.
This is an Icom 746Pro I repaired for a friend. The VHF transmit section was intermittant, and finally failed. This rig had me chasing my tail! First, I found the little potted VHF T/R relay had burned contacts and would not conduct when energized. Once that was replaced, the PA had almost no output. One of the 2SC2694 final output transistors had failed. That was repaired, which then showed drive to be extremely low due to a bad driver MMIC. That was replaced, and it came alive. However, after a bit of use, the transmitter again became intermittant. RF would leave the PA, go to the T/R relay, and disappear under the RF shield that covers the bandpass filter...but nothing out the other end! That area is nearly impossible to work on, since the radio has to be torn to pieces to get the board out, and is inoperable in that condition. I used the dremel tool and sliced the shield open and was able to trace the problem to a hairline crack in a surface mount resistor that supplied the coil voltage to the relay. That was replaced, and all was well. There's no doubt the resistor was the root of this string of failures. I used solder to stitch the shield back together, and it hasn't missed a beat, yet. Here's a few pics....
