Replacing the dashboard plastic PCB

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Fudgy666
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Re: Replacing the dashboard plastic PCB

Post by Fudgy666 »

boatbuilder wrote:Anyone know where to get those 2.54mm pitch terminal blocks? Don't fancy waiting a month for them to come from China!

I looked around quite a bit to see where I could get these, and the only ones I could find were from China.

Fingers crossed you'll have a little more luck. :ok
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Re: Replacing the dashboard plastic PCB

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boatbuilder wrote:Makes a bit more sense now. So when the ignition is switched on current flows through the 470ohm, then led, then diode to alt. Alt acts as a ground I presume in that case.

Then when the engine is running and the alternator is generating power, it pushes back current in the opposite direction which is stopped by the diode and hence the led goes out.
I've read somewhere that alternators sometimes have an exciter connection so maybe the alternator needs a voltage applied in order to start it up.
Yep that's pretty much it - the voltage travelling through the LED is the 'exciter' (and the 150ohm 'route' provides an additional or alternate path to that exciter). Although to confuse things I think most modern alternators are self-exciting (oouu-errr!)!!
Either way - the alternator, when it's not spinning, provides a ground for that circuit and the LED lights up; when the alternator spins it outputs 14.5 volts-ish on that line which causes the LED to turn off.

boatbuilder wrote:If it just relied on the voltage after the led, the 2v might not be enough to excite the alternator so that could be another reason for the 150 ohm bypass...It would provide a higher voltage to the alt.
Not saying I'm right about all of that, just thinking out loud!
FYI - The LED 'drops' the voltage by 2 volts, it doesn't 'leave' only 2 volts.
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Re: Replacing the dashboard plastic PCB

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Its been a while since I did electronics in college so I'm a bit rusty on it all! (1997)

Found a listing for the terminals in Sweden, gotta be faster shipping than China!
http://www.ebay.co.uk/itm/121557773649" onclick="window.open(this.href);return false;

And the voltage regulator...
http://www.ebay.co.uk/itm/231188488361" onclick="window.open(this.href);return false;
It's the L7810CV model that's needed - replaces the TCA700y original.
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Fudgy666
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Re: Replacing the dashboard plastic PCB

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boatbuilder wrote:Found a listing for the terminals in Sweden, gotta be faster shipping than China!
http://www.ebay.co.uk/itm/121557773649" onclick="window.open(this.href);return false;

Is there a listing for terminals with more than 2 Pins ? If I remember rightly, you can't just solder multiple terminals directly next to one another.

You either have to leave a single track gap, or move it up/down the track.

Might be worth bearing in mind ?
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Re: Replacing the dashboard plastic PCB

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Tried Mouser, Rapid Electronics, R S Components, Farnell etc? You couldn't have looked very hard this is in the first result on Google!
eg http://uk.farnell.com/te-connectivity-b ... price=true

Must try harder
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Re: Replacing the dashboard plastic PCB

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Fudgy666 wrote:
boatbuilder wrote:Found a listing for the terminals in Sweden, gotta be faster shipping than China!
http://www.ebay.co.uk/itm/121557773649" onclick="window.open(this.href);return false;

Is there a listing for terminals with more than 2 Pins ? If I remember rightly, you can't just solder multiple terminals directly next to one another.

You either have to leave a single track gap, or move it up/down the track.

Might be worth bearing in mind ?

Ah darn it. Just ordered a pile of the two terminal ones.
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Re: Replacing the dashboard plastic PCB

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boatbuilder wrote:
Fudgy666 wrote:
boatbuilder wrote:Found a listing for the terminals in Sweden, gotta be faster shipping than China!
http://www.ebay.co.uk/itm/121557773649" onclick="window.open(this.href);return false;

Is there a listing for terminals with more than 2 Pins ? If I remember rightly, you can't just solder multiple terminals directly next to one another.

You either have to leave a single track gap, or move it up/down the track.

Might be worth bearing in mind ?

Ah darn it. Just ordered a pile of the two terminal ones.

I'm at home working on the Van this Sat & I have a sneaking suspicion that I actually had a couple of strips of terminals left over.

If I do, and I can find them, you're more than welcome to have them for the price of the postage ?
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Re: Replacing the dashboard plastic PCB

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Great, let me know if you find them!

Heres what I've done so far - soldering a bit messy but I've tested it and it works. Replaced leds with new ones from Maplin.
Mines a diesel without a clock so it has the extra led for the heater plugs.
The wires at the bottom keep breaking off the board, so the screw terminals are pretty much essential I think.

Image

Image
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Re: Replacing the dashboard plastic PCB

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boatbuilder wrote:Great, let me know if you find them!

Heres what I've done so far - soldering a bit messy but I've tested it and it works. Replaced leds with new ones from Maplin.
Mines a diesel without a clock so it has the extra led for the heater plugs.
The wires at the bottom keep breaking off the board, so the screw terminals are pretty much essential I think.

Image

Image

Looking really good ! :ok

I'm PM you on Sat and let you know if I manage to dig out any terminals.
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Re: Replacing the dashboard plastic PCB

Post by boatbuilder »

Thanks, just wondering now why the headlight led resistor at the top is a different value than the others?
The others are 460 ohms and the headlight one is 120 ohms.
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Re: Replacing the dashboard plastic PCB

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Different forward voltage? If you are using blue or green - see table that I posted earlier.
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Re: Replacing the dashboard plastic PCB

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120 ohms seems very small though, way smaller resistor than any led on the chart. Wonder should I just swap it for a 470 like the rest?
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Re: Replacing the dashboard plastic PCB

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boatbuilder wrote:120 ohms seems very small though, way smaller resistor than any led on the chart. Wonder should I just swap it for a 470 like the rest?
Yeah - originally the headlight LED wasn't an LED at all it was a normal bulb hence why it has a different resistor.
If you are using a blue LED for the headlight indicator then you should replace with a different resistor.
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Re: Replacing the dashboard plastic PCB

Post by MidLifeCrisis »

Usually when you buy an LED it gives values for suggested current flow and voltage drop and there are 'calculators' online that you can use to determine what resistor to use for that LED (Google 'LED calculator')
I think I ended up using 270 ohms for my blue LED but your LED may be different
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Re: Replacing the dashboard plastic PCB

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boatbuilder wrote:Thanks.

Managed to find them !

Drop me a PM and I'll post them over to you Monday morning. :ok
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