Dashboard LEDs

[TT Tim]

Hi,

Can someone please tell me what spec I need to replace the LEDs in the dash? I'm not talking about replacing the dashboard illumination, I'm talking about the tell tails, such as indicators, MIL, frost warning etc.

I know they're 5mm but are they 12v or is the voltage reduced, somehow, in the dash?

Sorry for my ignorance, but this is new to me. :-)

Ta

Tim

[JensenA]

They are all 12v Tim.

[TT Tim]

Ta, so is the easiest thing to use 2.5v and a resistor?

Tim

[JensenA]

No Idea, electrics baffle me, all I know is that they are 12v, so replacement ones should just fit in. I bought mine from Halfords, they come with wires, I connected one to positive, earthed the other and fitted them in with a blob of silicone.

[Byker28i]

Why not buy the ones already made in the same format, or aren't they normal dash bulbs?

i.e. google says
http://www.m-99.co.uk/Car_Neon_LED_Lighting/Dashbo...

[Rufus Roughcut]

To the best of my knowledge the MIL,Turn and Handbrake Leds are 5 volt, i.e. the 'ballast' resistors are part of the pcb below is a pic of the rear of the pcb



I don't know about the others,, except to say the Ice warning is Tri colour and to my knowledge they are all 5v.

[JensenA]

I stand corrected then I guess my 12v ones work because I wired mine in differently, directly to the 12v circuit

[Tony69]

Hello,

I think L.E.D's you're referring to are the original TVR part numbers...
ME0187 GREEN 5MM
ME0188 RED 5mm

They are certainly NOT 12v but more likely 2.5V and (Probabilly) preceded in circuit with a 0.125W 680ohm resistor, I can't quite see from the shot of the PCB.

Anyway, I believe alternative L.E.D you need can be sourced from Maplin Electronics...
http://www.maplin.co.uk/Module.aspx?ModuleNo=2047
5mm Red LED WL27E £ 0.39
5mm Green LED WL28F £0.39

I would also like to check (seeing as you have it out of the car) the opposite side of the PCB in your picture (right hand side) as I found that one of the three diodes that are in-circuit to the L.E.D that displays the red/amber/green light for the temperature warning indicator in my car, was the wrong way around... this was the reason why my temperature warning indicator never worked correctly. Clearly an error by whoever assembled my PCB in the factory.

If you need any more information just let me know, I'm more than happy to disassemble/test my board and put a meter across the L.E.D to confirm the voltage/size.

By the way... as I'm sure you know, replacing an L.E.D should be unnecessary unless a serious fault has occurred and the L.E.D has been burnt out by excessive voltage.

In any case... test the voltage before installing the new L.E.D, I think it should be 2.0 to 2.5 VDC and make sure you install the new L.E.D observing the correct polarity... the longest leg of the new L.E.D will be positive (the anode).

Check here for detailed technical information on the alternative part.
http://www.maplin.co.uk/Media/PDFs/CK37.pdf

Please forgive me if I'm telling you things you already know.

Best regards

Tony.

[TT Tim]

Thanks for the reply Tony,

Now I'm really confused, I have replaced the handbrake tell tale LED as that didn't illuminate.

I also replaced the Ice warning and Main Beam LEDs, as these were damaged when stripping the dash.

All these I have replaced with 5v units, I did use a 5v transformer to check the other LEDs illuminated, which they did, I am assuming, from what you said that I'm lucky that I haven't blown the existing bulbs?

So, I take it that I now need to replace the bulbs I've changed for 2.5v units?

Can you give me the correct Maplin items for:

Tri-colour - Ice warning
Main Beam
Handbrake tell tail

Many, many thanks for your help.

Tim

[Tony69]

Hello Tim,

I took the dashboard PCB out of my Cerbera this afternoon and tested the L.E.D's and voltages... Here are the specifications for the L.E.D's and the equivalent Maplins part numbers.

M.I.L Red 5mm 2.5vdc WL27E
Handbrake Red 5mm 2.5vdc WL27E
Indicators Green 5mm 2.5vdc WL28F
Ice Warning Tri-Colour 5mm 2.5vdc YH75S
Main Beam Blue 5mm 4.0vdc JA24B

Demist Red 5mm 2.5vdc WL27E
Aircon Blue 5mm 4.0vdc JA24B

All the L.E.D's above are 5mm and all of them should be 2.5vdc with the exception of the "blue" L.E.D that is 4.0vdc.

If you have fitted 5vdc L.E.D's, where 2.5vdc L.E.D's are usually fitted, you won't do any harm as the load is simillar (in fact slightly less than the lover voltage type) but you may find that the 5vdc L.E.D's will not illuminate as they have insufficiant voltage. The only way to know for sure is to try it.

By the way... In my Cerbera, the Aircon light was "clear blue" (not defused) and almost impossible to see when it was on. I replaced it with JA24B that has a defused lens and it now look as it should... it mathes the red L.E.D for the demist in intensity, defused colour and I can now tell when it's on, Great...

Let me know if I can help with anything else. I should have spares of these components if you need them.

Best regards Tony.

[TT Tim]

Thanks very much for your help Tony,

I'll be off to Maplins, or may order from RS this week.

Glad I hadn't finished putting everything back together. :-)

Thanks again

Tim

[FarmyardPants]

Tony69 said:

By the way... In my Cerbera, the Aircon light was "clear blue" (not defused) and almost impossible to see when it was on. I replaced it with JA24B that has a defused lens and it now look as it should... it mathes the red L.E.D for the demist in intensity, defused colour and I can now tell when it's on, Great...

I was in Maplin today and picked up a JA24B to fix the invisible aircon light, thanks for the heads up.

Any hints on changing it? I presume one reaches up behind and unscrews something to detach the panel and it's plain sailing from there?

Thx

[Tony69]

Yes, it’s quite a nice job,

1) gently reach up behind the panel and you’ll feel two small, flat, metal brackets (very much homemade) that are held in place by two small nuts. One bracket is directly over the hot air control and the other is directly over the cold air control.
2) When I found the right sized socket (about 4/5mm I seem to remember) you can just hold the socket in your fingers reach behind the panel and undo the nuts. Watch out for the little washers under the nuts.
3) When you have removed all four nuts/washers... the two thin metal brackets will come away with a bit of a wiggle. Now you be able to lift out the panel with the hot/cold controls on it
4) Now with a marker pen, make a small mark on one side of the ribbon cable to remind you which way round it needs to be when you put it back. Now go ahead and unplug the ribbon cable.
5) Now the panel is free... it is quite easy to replace the blue L.E.D

Hate to mention this as I’m sure you already know, but... an L.E.D is a diode and must be connected the right way round. On the new L.E.D you have, the positive (anode) leg is the longest of the two.

If (like me) you didn’t put a multi-meter across the original L.E.D on the circuit board to determine which way round to solder in the new L.E.D, not to worry, you can simply remove the existing L.E.D, plug the ribbon cable back on to the panel (make sure it’s the right way round) and turn on the ignition... now you can just (carefully) “hold” the new L.E.D against the circuit board where it is to be soldered, if it lights... it’s the right way round.

If the L.E.D is connected the wrong way round, you won’t do any harm, it just won’t illuminate.

Let me know if you have any problems...

Tony

[FarmyardPants]

Very helpful, thanks. Might take a few pics when I get round to doing it and post em up.