Ferguson dab radio frg-r116d. display back light not working. is there a way it can be changed
It's not easy - we had one in our Repair Cafe yesterday with the same problem. The backlight is a LED that is moulded into a perspex screen located behind the display. You will need a soldering iron, PH1 screwdriver, fine pliers, a file, Stanley knife, perspex glue and replacement cold white LED (preferably 3mm, but 5mm will do).
To get at it, take out the front panel assembly (4 deeply recessed screws accessible from the back, and 2 at the front, accessible through the bottom). Then detach the front PCB assembly between the speakers (4 screws). The display is held onto this by 2 screws - remove the connector to the rest of it first. But before this, make sure power is getting to the PCB - power up the radio and check for about 5 volts between pins 11 and 12 of the connector. Also check that you can see something on the display by shining a bright light at it - if not, the display itself has broken - so no point in proceeding.
The LED is at the right side of the display. Cut its leads and desolder remains from the PCB. Carefully lever up two metal tabs at the opposite end of the display (DO NOT ATTEMPT TO REMOVE THE WHOLE METAL COVER). You can then slide out the backlight unit to the left. The rectangular-bodied LED is superglued into the perspex - carefully prise it out with pliers.
A 3mm LED should then fit the slot. Otherwise, file part of the dome of a 5mm LED to make it fit. Either way, push the LED into the slot, refit the backlight assembly and connect its leads to the PCB - positive to hole nearer to the connector. Then power it up to check it works. If all is good, apply a few drops of perspex glue round the LED body to retain it: this will also reduce light leakage. Carefully push back the two metal tabs.
There are two surface-mount 15 ohm resistors (marked 150) on the PCB near the LED. These allow too much current through the LED, so to reduce risk of a further failure, remove both and replace with a single 150 ohm surface-mount resistor. If you have to use a leaded component, use the smallest you can and ensure it doesn't foul anything else when fitted. (This step is a nicety, but if not followed, the LED could fail again - lousy Chinese 'design'...)
The back end of the LED will protrude further to the right than the original, which will foul the right speaker mount. Remove and discard the screw that will be affected and cut away sufficient plastic for the screen to fit properly.
Then reassemble. Illumination might not be as even as before, but the display should be clearly visible. HTH.