Disco 2 Why is simple stuff not simple? LCD dash lamp

Si Click

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1,506

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Lincolnshire

• Nov 5, 2018

• #1

So down to working on very minor issues. The LCD display in the instrument binnacle is not illuminated.
Simple, track down the right part number for the bulb (YAW100020) not the same as the Clock bulb, order it, replace it, simple.

The new bulb is a perfect fit and looks fine - but so does the old one....
LCD still not illuminated.

I'm sure this bulb is not independently fused, so a short in the loom which would require replacement to fix, a rotten connection in the binnacle itself? Has anyone had this before and is there a fix that is worth the effort/expense to do?

 

brian47

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8,867

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Bridgend, Mid Glam. Somebody's got to live here.

• Nov 5, 2018

• #2

It's just one of those strange "Murphy's Laws", "A five minute job will always take a couple of hours plus those five minutes".
Regarding your trouble with the LCD backlight, it's unlikely to be a short circuit, that would start blowing fuses or burning wires. It's more likely to be a broken wire or a bad connection somewhere, probably in a plug and socket. Another cause could well be a poor soldered joint (known as a dry joint) on the binnacle printed circuit board, or in the worse case a broken or burnt printed track on the board.

 

sierrafery

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17,871

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Arad/Romania

• Nov 5, 2018

• #3

The clock and the radio are illuminated? ... if yes you should check the new bulb with direct feed cos i've seen cases when a bulb was DOA

 

Si Click

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1,506

Location

Lincolnshire

• Nov 5, 2018

• #4

Clock and radio are good. I'll check the bulb itself, but my money is on a dodgy connection in the binnacle. Can they be opened easily without breaking them?

 

sierrafery

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17,871

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Arad/Romania

• Nov 5, 2018

• #5

Yes, you can get quite easy access to the back of the PCB if you remove it's casing

 

Si Click

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1,506

Location

Lincolnshire

• Nov 6, 2018

• #6

The new bulb was tested by swapping with the clock bulb, and it works (as does the old one). So this is not a bulb failure.
I opened up the back of the PCB and was confronted with the picture below. There may be some slight discolouration near the bulb, but nothing I am going to fix clumsily with a soldering iron.