Author Topic: Electrical problem with '67 gauge cluster  (Read 532 times)

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Offline 67FBGT

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Electrical problem with '67 gauge cluster
« on: December 23, 2017, 01:16:58 PM »
I'm wanting to get my '67 mobile again after a 2-3 year lay-up.
Have finally refurbished the gauge cluster including new bulbs (LED), lenses etc. So, cosmetically, all looking good.
But the little gauge voltage regulator on back gets mighty hot with the key on (Acc or Run), in fact heats up quite rapidly until it's too hot to keep hold of. So I installed a new one, but problem persists.
By trial and error I've discovered that if I disconnect the black wire from the gauge voltage regulator on the back of the fuel gauge the heating-up disappears.

Am I right in thinking that the gauge voltage regulator is there to control the voltage to the small gauges? I have four - fuel and temperature as separate small gauges, plus oil pressure and alternator gauges housed together in the RH large binnacle.
AFAIK the gauge cluster lighting is a separate circuit, driven off the light switch, so the new LEDs surely couldn't be the problem.
So I presume I have a short somewhere, causing grief to the gauge voltage regulator. Could the fuel gauge itself have shorted, or perhaps the fuel sender unit? Anyone struck this issue before?
Thanks in advance.

Online BAC

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Re: Electrical problem with '67 gauge cluster
« Reply #1 on: December 24, 2017, 01:23:04 AM »
Sounds like you're already halfway to finding the issue.  Most likely a short somewhere in the fuel gauge circuit: either the wiring, sender unit or possibly the gauge itself.   One question: does the fuel gauge still read correctly when power is applied?

Time to get hold of a multimeter and a wiring diagram and get to work.  Given there's a long run of wire in that circuit, my money would be on the wiring.
Cheers,
Brian

Online shaunp

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Re: Electrical problem with '67 gauge cluster
« Reply #2 on: December 24, 2017, 07:50:24 AM »
They get hot they are just a bimetal strip that opens a set of points so it doesnt regulate it just pulses the volts and gauges average it. , its best to put a 5V solid state regulator in it

Offline 67FBGT

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Re: Electrical problem with '67 gauge cluster
« Reply #3 on: December 24, 2017, 08:27:46 AM »
Quote
does the fuel gauge still read correctly when power is applied?
Car has been parked up, no fuel in tank as yet, will check that point when I've refuelled, thankyou! Hopefully fresh fuel and the car will start OK, the tank was on E when engine last run and what was left has evaporated. Life has got in the way meanwhile.

Quote
They get hot they are just a bimetal strip
Quote
best to put a 5V solid state regulator in it
Just worried about a wiring melt-down or behind-dash fire. Will see what the vendors have by way of a solid state upgrade, I don't know if the replacement is that type or the old style.

Thanks for your input and time guys, very helpful and much appreciated, that's given me some direction as I'm not confident with electrics.
Merry Xmas and thanks again.

Online shaunp

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Re: Electrical problem with '67 gauge cluster
« Reply #4 on: December 24, 2017, 04:10:46 PM »
Car has been parked up, no fuel in tank as yet, will check that point when I've refuelled, thankyou! Hopefully fresh fuel and the car will start OK, the tank was on E when engine last run and what was left has evaporated. Life has got in the way meanwhile.
Just worried about a wiring melt-down or behind-dash fire. Will see what the vendors have by way of a solid state upgrade, I don't know if the replacement is that type or the old style.

Thanks for your input and time guys, very helpful and much appreciated, that's given me some direction as I'm not confident with electrics.
Merry Xmas and thanks again.

You can buy a 5v reg  from Jaycar for a couple $. you want a somthing like a 7805 reg , ground the center pin and case put 12v on the left leg and you should get 5 on the right leg , you can put some caps in as well but no need for gauge cluster. If you google a 7805 5v reg circuit  you'll find it. put some heat sink paste on the back.

Offline 67FBGT

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Re: Electrical problem with '67 gauge cluster
« Reply #5 on: December 25, 2017, 10:25:23 AM »
Ah, thankyou for the tip, there's a Jaycar not too far from me as it happens.
Didn't know about heat sink paste, always something new to learn when in the midst of a problem.
Awesome, thanks for the advice, and compliments of the season!

Online shaunp

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Re: Electrical problem with '67 gauge cluster
« Reply #6 on: December 25, 2017, 09:39:47 PM »
Ah, thankyou for the tip, there's a Jaycar not too far from me as it happens.
Didn't know about heat sink paste, always something new to learn when in the midst of a problem.
Awesome, thanks for the advice, and compliments of the season!

Yep the sink paste will transfer the heat to what ever you bolt it to.

 

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