(2 di 15)23/08/Ħ I no take any liability for this repair instruction. Put all boards back and front panel to the main body. It is very important insulate this transistor from metal shield (it is grounded) because all transistor legs have no ground contact! Then shorten new tr. Other type is ok if you check 2SB1201 current and voltage values. Next i drill to the metal shield one side (most of all emptiest room) and replace original 2SB1201 to BD650. I remove it using normal 50W Weller solderstation and desolderbaraid. Because there is no enough cooling area in printed circuit board, this transistor go faulty. There is one bigger transistor what is Q302 2SB1201 PNP transistor. In the metal box has few component witch make cold cathode lamp requiring voltage. Second i read carefully what it made for IC-746 repairing. First i change backlight cold cathode lamp but no help. I think that this problem occur Europe model IC-7400 too.
Ic 746 pro manual pro#
IC-746 PRO problem Referring IC-746 model backlight problem i meet same think newer model. The heatsink may be removed at a future date to replace IC151 (hopefully not) by twisting it sideways with pliers. Position the loose cable in the heatsink slot as shown and reconnect it to the circuit board. Check that the leftover epoxy has setup hard. Place the heatsink into position as before and insure that it is flat on the chip. JB Weld has good thermal conductivity and good high temperature characteristics. Clean the heatsink with a solvent (like acetone) and apply a small amount of JB Weld epoxy to the top half of the heatsink wall. Apply a small amount of heatsink grease (as used in your PC)to the top of the IC. Unplug the gray cable with the black band and move it out of the way. The heatsink should be clear of any other components. The proper position for the heatsink is flat on the chip and touching the case as shown in the picture. Use a small file to remove the aluminum burrs. You have to make one cut with a hacksaw to reduce the length to 3/16 inch (5mm). The source of my aluminum heatsink is from Radio Shack (PN ). a thermal path to the aluminum case, and 5. My heatsink requirements are as follows: 1. Adding an external heatsink for IC151 is cheap insurance against potential failure. The legs of this very small MMIC chip become the heatsink for the 1/4 watt of heat generated. In normal operation, IC151 dissipates 250 milliwatts (with 330 mw max rating at 25 deg C ambient).
Ic 746 pro manual driver#
Icom's position is that voltage spikes are the source of the problem but users have observed that this driver IC (IC151) runs "hot" and think that failures are from thermal stress.
Ic 746 pro manual manuals#
1 KB2LJJ Home Radio Mods Database and Manuals IC-746 Pro IC-746 PRO Heatsink for PA Driver The IC-746PRO has had a history of failed upc1678g ICs resulting in no RF output.
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