LCD Repair

• This is the guide that I followed on repairing a failing LCD Dot Matrix display on my HT1550-XLS UHF R2 radio. These WARIS portable models are highly desirable and are great radios. The custom 4 line LCD Dot Matrix is discontinued and apparently unobtanium. I took the gamble to attempt to repair it knowing that I could break it very easily.
  • [LCD Repair guide - http://p1repair.com/blog/2013/05/30/lcd-repair-missing-lines/]
• Step 1: Disassembly
  • I won't cover destuffing the radio or getting down to the LCD. You should be able to find several examples of destuffing and disassembly on YouTube to get you to the guts of the radio or device you are working on.
  • When you get down to the LCD board itself you have to peel off a protective sheet from the PCB side of the assembly. Then you will have access to the six (6) LED backlight solder points that connect the rear PCB to the glass LCD display itself. Unsolder these 6 connections carefully.
  • Once you unsolder the backlight, carefully flip the PCB and glass LCD away from each other using the micro-ribbon flex cable as a hinge. You are now fully disassembled and ready to begin the actual repair procedure.

• Step 2: LCD flex re-soldering
  • USE A DRY IRON TIP!!! No flux, no solder.
  • I tried using the low (400`F) setting recommended in the guide linked but even using something as thin as a post-it note I was not able to achieve the melt point of the solder used to allow the connections to reestablish.
  • The outermost 4-5 circuits on the ribbon flex cable were not connected to a trace on the PCB. I used this small area to test heat settings and how much damage a direct contact with the soldering would cause.
  • After experimenting with temperature on my Weller iron and found that I could go up to 480'F and not melt the material that the flex cable is made of in short 2-3 second contact using no silicone or paper head dispersion layer. This seemed to achieve solder melt but avoid damage to the membrane itself.
  • EXPERIMENT WITH YOUR HEAT SETTINGS BEFORE YOU COMMIT TO TOUCHING THE CABLE WITH YOUR IRON!!!!
  • I took the gamble and used the dry 480'F iron in a slow to moderate speed pass across the flex cable at the very last 1-2mm of the cable noticing very slight distortion of the flex cable membrane indicating heat transfer but no membrane melting was observed. It appeared to melt the underlying solder of the cable connecitons.
  • I moved up the cable ~3mm and made another pass slowly across the solder interface area noting the same membrane heat distortion.
  • That should be it. Hope it worked.....

• Step 3: Test your repair
  • I connected all the radio PCB boards back together outside the chassis of the radio and held a battery in place with a rubber band to power up the unit to ensure my repair was successful before reassembling the radio.
  • IT WORKED!!!
  • I then reassembled the radio and powered it up to a fully functioning LCD display.
  • Thanks Ben at [P1Repair Blog] for the instructions on how to undertake this kind of repair!!