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Discussion Starter #1
I am trying to bench test my gauges. My question is what size 12V supply would be sufficient? I tries a 12 V 1.6 amp supply and the lights would not even come on. I know how to test the tach, but the fuel, amp and temp gauges, I don't have a clue. :( . Any help appreciated.

Thanks
Mike
 

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My regulated bench power supply is 20 amps. Way overkill but that's what I have. Sounds like you are trying to use a little 12 volt convertor and not a bench power supply.
A variable potentiometer from ground to the sensor inputs on both the gas and temp gages will tell you if they work. It won't tell you how accurate they are. The amp meter is really a millivolt meter and you need to hook it up across a shunt to make it move.
http://www.chevelles.com/techref/ftecref18.html
 

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Discussion Starter #3
John,
It's not a converter just a stand alone supply from some test eqiupment I had lying around.
I guess I'll need a supply with more amps. Is the a convenient spot to input the 12V to the cluster?
Does it matter what terminal the variable pot goes to for the temp and gas?

Thanks!
Mike
 

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Discussion Starter #5
Thanks for the help John,
Actually, the cluster is out of the car. Is there a single spot where I can hook the 12v positive lead to test the gauges or is there a specific terminal on each gauge where the 12 volts would go? I see the tach is the only gauge that is labled. I'd hate to put the dash back together and either have a gauge not work ora light not working.

Thanks again!
Mike
 

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You will need at least 4 amps of current.
You will need a 12 v source such as a battery (fuse the pos lead), battery charger or power supply. It is easier if you have a mating connector for the gauge cluster but not necessary. Connect + (12v) to pin 7 (gauge power) or any of the terminals that pin 7 connects to (follow the traces from pin 7) and - (neg) to any clean metal surface of the cluster. To test the dash lights connect another + (12v) wire to pin 2 (Dash lights). To test the oil light (no oil gauge for ss clusters) connect a ground (metal case)to pin 6. To test the turn signal lights connect another +12v to pin 1 for left and pin 12 for right. To test the fuel gauge, connect one end of a 45 ohm resistor to pin 11 and the other end to ground (metal case).
This should registor 1/2. If you don't have any resistors, no connection will be past full and ground will be empty. To test the temp gauge, connect a 75 ohm resistor from pin 10 to ground, this should registor about 210 deg. 50 ohm = 250 deg, 75 ohm = 210 deg and 270 ohm = 100 deg.If you don't have a resistor, open will register far left and ground on pin 10 will register past 250 deg. To test the brake light connect a ground to pin 8. To test the high beam light connect +12v to pin 5. To test the amp gauge connect a AA battery + on pin 3 and - on pin 4, it will registor over 40 amps charge (depending on condition of battery), reverse the AA battery and it will register over 40 amps discharge. To test the tach you will need a pulse generator or a running car that has points or early (no computer) hei ignition. Hook the + from the car battery to pin 7 and - from the car battery to any clean metal surface of the gauge cluster. Hook the negative side of the coil (points ign) or tach terminal(hei ign) to pin 9. start car up and rev motor, tach should respond.
 

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Discussion Starter #7
Hey Steve,
I appreciate the detailed instructions. I figured out the pin numbers for the connector on the cluster and wrote the corresponding description according to your instructions. The only thing I am not sure about is, you say to connect +12v to pin 5 (gauge power), but when I trace pin 5 it goes only directly to the high beam light as you refer to later on. I'm a little confused.

Thanks for your patience,
Mike
 

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where can a person buy resistors of the type described above for gauge testing?
 

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I am very sorry, there is no information like misinformation.
The power feed for gauge clusters is PIN 7 not pin 5. Pin 5 is for idiot light clusters. Very sorry. I rechecked the other pin #'s and they are correct as stated.
Resistors can be bought at radio shack, get 1/2w.
 

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Discussion Starter #10
Thanks for checking that Steve. Now I at least will be confident the gauges will work when I finally get them installed. This kind of work will keep me busy during the cold winter months, since most of the work I have left is the body.
I'll let you know how things work out once I get the resistors.

Thanks again.
Mike
 

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Discussion Starter #11
Hey Guys,

I have checked all the gauges and tested all the lamps with the excellent detailed instructions Steve wrote, so far so good.


Steve, the only thing I still need to test is the tach. I don't want to fire up my 68 camaro (points), and my other vehicles are too new. You said I could use a function generator, which I am slightly familiar with. My question is what kind of wave do I output, sine square, ect? Does the amplitude matter? Any help again appreciated!

Thanks!
Mike
 

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Square wave seems to work OK, will need about 10-15v amplitude you may need to play with this. I don't think you can give it too much amplitude because the tach circuit has a clamping diode on the input but just to be safe start low and increase until the tach responds. Another option is to spin a distributor with a drill. If you have a spare distributor laying around, points or early HEI (no computer), hook +12v to + side of coil and + on tach, points and tach lead to - side, and ground to distributor metal and tach case. You don't need rotor, cap or plug wires. Should be able to chuck something up in the drill that will fit in bottom of the distributor shaft to drive it.
 
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