From Jim, KD6QVO and Lou, KE6EOI
     
     My bad experience with my Alinco DR1200T data radio prompted me to 
     seek a better solution than just replacing lamps every year or sooner.  
     I posted an ALLUS bulletin on Alinco DR1200T lamp burnouts.  
     
     With the technical expertise of Lou, my DR1200T now has all lamps 
     replaced and an OFF/ON switch installed to control all lamps but the 
     Power LED.  Here are the instructions as written by Lou for lamp 
     replacement info and how-to stuff.
 
     Alinco shows 2 P/N's in the DR1200T svc. manual. BQ031-40608A used for 
     the 3 switches (these have a removable blue filter), and BQ031-40604A 
     the 2 to backlight the display. Only BQ031-40608A is available from
     Alinco at $1.50 ea. plus shipping ($3.00), so you must remove the 
     filter for the display application. You need a total of 5 lamps for 
     the job, replace all 5 since the good ones will die soon. The lamps 
     from Alinco are T1 (1/8 dia x 1/4 long with 1 3/8 leads) and are 
     identical to Chicago miniature CM 8111 or JKL P/N 8111 with the 
     following ratings: 14V; 0.065A; 0.150 MSCP (intensity unit), and a 
     10,000 Hr life (actual is more like 5,000 Hr). 
     
     Slightly above average soldering skills, a small soldering iron, small 
     dia. solder (0.015 dia.) and a solder sucker or solder wick is required 
     to replace these lamps. The pads are small and the traces are fine and 
     close. To access the lamps, remove the top and bottom panels, and the 
     front bezel, which is retained by 2 nuts at the mic. connector and 
     channel sw.  Now remove the 3 screws holding the display PWA to the 
     chassis.  DO NOT remove the display from the PWA. The 2 display lamps 
     are at either end of the display. Use the tubing on the old lamp leads
     to keep the new leads seperated if they short good by small traces! The 
     solder sucker is needed to clean out the small holes for the switch 
     lights. Don't forget replace all 5 lamps!
     
     To add a switch in this lamp power line requires advanced soldering 
     skills, a push on push off switch - mfr. C & K p/n 8161 SHZ (standard 
     configuration with a 1/4-28 mounting bushing), and a small xacto knife, 
     and about 1 ft of 26 or smaller AWG stranded wire, ribbon cable works 
     great. Total rework time is approx. 1 1/2 hr.
 
     1. Center a 1/4 inch switch mtg. hole on the side of the chassis adjacent 
        to the channel selector switch approx 3/8 inch above center.
     2. Remove the display from the PWA. Before it is reassembled the rubber 
        connector must be removed and flattened by pressing on it with your 
        thumb to increase its length slightly to insure good contact to the 
        PWA.
     3. Locate the solder tabs for the display lamp near the volume control, 
        there is a VIA about 3/8 inch from the bottom tab.
     4. Solder a 6 inch wire into this VIA so it exits on the side of the PWA 
        opposite the display. Run the other end to the new switch.
     5. Now for the tricky part! This trace runs from this VIA under the 
        volume control to a connector marked CN202, pin 12. It's near the 
        power on/off switch and LED. Cut this trace with the xacto knife, 
        anywhere from this VIA and pin 12. The point I picked was 
        approximately 3/8 inch from the VIA right below the edge of the
        metal housing for the display, right before it goes under the volume 
        control. Watch out for the trace just below it.
     6. Connect another wire from the other side of the switch to the bottom 
        side of the connector CN202 pin 12.
     7. Test for a clean break of the trace (do not add the display to the 
        PWA yet) by connecting the radio to a supply and turn on, lights 
        should go out when the button is pressed. If the switch does not 
        control them inspect for a clean cut. 
     8. Checking the display contacts. Reinstall the display (do not screw 
        to the chassis yet) and power up the radio again. Rotate the 
        frequency knob to insure all the display segments work. If there is 
        a problem, try bending the tabs so they apply more force on the 
        rubber connector. Last resort is to remove the display again, and
        stretch the rubber connector once more.
     9. Now you are home free! Install the switch, notch the case and 
        reassemble.
 
     After performing this delicate operation, and reviewing the lamp specs. 
     a simpler alternative to the switch would be to use 18V lamps. Here are 
     two equations that predict lamp life and intensity VS operating voltage: 
     Life multiplier = rated volt divided by applied volts to the 12th power. 
     Intensity = applied volt divided by rated volts to the 3.5 power. From 
     this equation 18v will give 20x life at a 41 percent reduction in 
     intensity. 12.5v operation with 14v lamps = 3x life increase, but 
     reduces the transmitter power 10 percent. I operated the 14V lamps at 
     11V to simulate 18V lamps at 13.5v and found the intensity satisfactory. 
     The P/N for 18V lamps is Chicago Miniature CM 7220 or JKL 7220. They 
     should be available from a local electronic distributors or mail order 
     distributors such as Allied in Fort Worth 1-800-433-5700 or Newark in 
     Chicago 1-312-784-5100. I doubt it if radio shack will stock them. 
 
     We hope the above information will help you.  Address any comments or
     suggestions to me, Jim, KD6QVO.