Refurbishing a W124 instrument cluster – Part 2: W124 outside temperature display

In this series I am refurbishing my W124 instrument cluster.   In the last part, I removed the cluster and lubricated the speedo cable.   For this part, I am repairing the W124 outside temperature display.

The main problem with these displays is that when exposed to too much hot sun, the LCD panel ‘bleeds’.   Over time, this makes it increasingly illegible, not to be mention ugly.    I previously fixed the displays in both my old 300SE and the 560SEC.    The W124 outside temperature display is basically the same as the unit found in the W126 and W124.  They are just in different housings.

The good news is that replacement LCD panels are available.    The LCDs used changed in about 1988, so for the 300TE I needed to use the newer version of the LCD panel.    I also bought another earlier one to fix a spare W126 unit I have on hand.

The W124 outside temperature display unit just screws into the back of the instrument cluster.   Its the first thing you have to remove to get the gauges out, so now was a good time to repair it.

To repair the W124 unit, there are four small screws that must be removed.   On this model, the upper and lower parts of the housing must come apart to get to the front part where the LCD panel is.

The later unit as on my 300TE has a more sophisticated baffle for the bulb that illuminates the display.   Otherwise there are basically the same, with the two black ‘blocks’ that transmit the signal from the PCB to the LCD panel.     The dot at the top of the LCD panel faces upwards.

As I purchased two LCD panels, a new one and an old one, I had the issue of not being able to work out which was which.   Probably it would be evident with a strong magnifying glass, but I couldn’t tell.   I tried one, and as it turned out, it was the wrong one.    The W124 outside temperature display is a separate unit to the instrument cluster, so its possible to test it without installing the entire instrument cluster.

It also looks like the blub in my unit has blown.  It would be easy to change if you are good at soldering.   This is soldered onto the PCB, and I’m terrible at soldering.   For now, I’m going to leave it as is.    I’m still pretty happy with this repair.