HOW-TO reach the front panel of IC-728
for changing a burnt display lamp
Recently one of the three display lamps of my IC-728 burnt. I don't really know how it could happen, since it apparently broke while moving the transceiver to another location.
The user manual does not describe how to reach and change the lamp, although on the schematic diagram they are clearly indicated. Therefore I had to find the way on my own.
DISCLAIMER: if you decide to follow the following instructions I do not consider myself responsible for any material loss and/or damage or personal injury. Follow the procedure described at YOUR OWN RISK.
PROCEDURAL NOTE: you will remove a LOT of screws. You are strongly advised to prepare 3-4 small boxes to keep them separated according to their original location (upper/lower panels, front panel mounting support, ...)
- Unplug the transceiver from all cords: mike, CW key, power line, ...
- Follow the user manual instructions on unscrewing and removing the upper and lower covers.
- You do not need to remove the front plastic panel as I first though of, as well as the heat-sink
- Position the 728 in its natural state and locate the following screws couples:
- on top those keeping the front panel connected to the heatsink
- on left side the couple keeping the front panel screwed to the circiut-board metallic frame (lower part of the RTX)
- on the right side, as on the left
All these 6 screws have the same goldish metallic colour.
- Gently lay the 728 on one side (careful not to touch any component on the board or damage the little loudspeaker!)
- Move apart the front panel paying attention not to break any of the connecting wires. You won't be able to move it too far away, but it is enough space for (un)soldering the lamp
- Locate the lamps by looking for three identical holes on the side of the green board that could be considered close to the top of the transceiver
- Unsolder carefully the burnt lamp and extract it from its location
- Remove the yellow rubber cover from the lamp and put it together with removed screws.
I couldn't locate on any paper or Web page IC-728 lamp characteristics, so I measured at least their operating voltage. Across lamp terminals I could measure about 12 volts (obviously after connecting the power cord and switching the RTX on)
I have heard that ICOM's original part costs 2.5 US$. Mine was 0.4 US$.
- Go to your favourite electronic parts store with the lamp and buy a eplacement. I have been told they are used in car-audio displays. Be areful to buy the 12 volts one, and not 6 V!
- Come back home, cut the terminals to the lenght of the original lamp, ut the yellow rubber on, solder it in place
- Test if it works: plug the power cord to IC-728 and switch it on
- If everything works, follow backwards these instructions to get your C-728 reassembled (from 6 to 1)
Final note. There is probably a current rating difference between the eplacement I got and the original lamps. In fact the new one is more dim han the other two. If you want you can replace all original lamps with ew ones, and there is actually place for a 4th one on the IC-728 front anel PC board.