Ruark Vita Audio R1 Mk2 LCD Backlight dim - replace leds - Page 1
Forum section: electronics / repair

author: rh100605
author_rank: Regular Contributor
timestamp: October 16, 2023, 06:38:56 pm
content: The Ruark R1 Mk2 (Ruark on the front) has an LCD display. The symptoms are that the LCD is readable but dim.N.B. The Ruark Vita Audio R1 Mk2 (Vita on the front) has different code and menus but uses the same display board.Normally this means one or more of the four 0603 white LEDs that are the back-light have failed. See attached photo.It is possible to replace these LEDs but you need to be in the right mood and be very careful.You are going to remove the LCD and back light box from the PCB as one unit. Then remove the long white PCB under the LCD pins that carries the LEDs.Be very careful not to strain / bend the legs on the LCD they are not repairable.1. Remove the display board from the radio by disconnecting the flat cable from the board and removing the 4 screws that hold the board to the front panel.2. Flood the ten LCD connections on the board with "quik chip" flux and then low temperature solder.Do the same with the A and K LED tabs and then solder suck / solder wick both tabs until they are free in thePCB3. Push back the two plastic latches that hold the bottom of the lcd lightbox to the board and then insert a thin blunt shim between the board and light box.The light box will lift under light constant pressure and increasing size of shims.4. Push back the Upper two plastic latches holding the light box to the PCB and ease up the light box further with a plastic tool .The light box complete with LCD will lift further.5. Heat the low temperature solder on the pins and insert a plastic shim at one end and then the other.Assuming the A and K tabs are free, it will be possible to lift the light box and LCD further6. When the LCD and backlight are removed from the PCB strap the connections with a piece of thin wire and solder. Then have a rest!!!--------------------------------------------------------------------------------------------------------------------------7. Using flux and solder wick clean all the ten LCD vias and the A and K vias on the PCB. They must be very clean and clear.Use a hot iron as some are connected to the power planes.8. Using a needle point iron cut the two clear plastic tabs at the 1/3 and 2/3 points of the long white PCB under the LCD connections.9. Using a sharp scalpel clear space at each end of the long white board so that it can slide out backwards. It may only need the white seal to be pushed down / away.10. Using plastic tool or blunt pin lift the centre of the white PCB until it is clear of its surrounds and push a thin shim under to hold it up.Then push it to the left or right fully until one end comes away from the light box and can slide out backwards11 Apply a DVM in diode mode across the A and K tabs. All 4 white 0603 LEDs should light dimly.Replace those that do not light noting the polarity and checking with the DVM after fitting.Clean up all flux thoroughly with Flux remover.12. Replace the board into the light box , remove the wire strap on the LCD connections and put the assembly back into the board.Tack Solder A and K tabs and check the the back-light still works and that the PCB is seated properly.13. Then re-solder all the LCD connections and test. The impedance's are very high and current low. Clean up well.Any solder or flux between the pins can lead to the display not working or the LCD charge pump between pins 1,2 and 3producing a low voltage on pin3 ( less than 6 volts) giving a faint or low contrast display. The 1206 capacitors are between 0.1 and 1 mfd X7R.I told you this was not for the faint hearted or to be done in a hurry!