voltage regulator problem

[philip arthur 0]

1970 boss gauges do not work. burned out the printed circut board in first go around. new circut board instauled .no gauges yet. instauled instrument voltage regulator.no gauges yet. the violet power wire to the dash has 9.7 volts wile not pluged in.does this have to be 12. next plug in dash to wireing harnes the 9.7 dropes to 3.3 wile 2.88 volts reach the instroment voltage regulator? what do i check next?

[Mach1 Driver 560]

There is a 10 ohm resistor wire that is violet in front of the voltage regulator. This lowers the voltage. What happens most often is that one or more gauges (oil, temp, fuel) are removed and when replaced one or more of the gauge posts contacts the metal housing of the panel. If any gauge post contacts the panel it creates a short and the voltage to all the gauges drops and none of them work. That sounds like your problem. The schematic below shows the gauge circuit. You will need an ohmmeter to figure out which one(s) are grounded. Shout if you need help diagnosing further.

[Midlife 814]

2 hours ago, Mach1 Driver said:

There is a 10 ohm resistor wire that is violet in front of the voltage regulator. This lowers the voltage. What happens most often is that one or more gauges (oil, temp, fuel) are removed and when replaced one or more of the gauge posts contacts the metal housing of the panel. If any gauge post contacts the panel it creates a short and the voltage to all the gauges drops and none of them work. That sounds like your problem. The schematic below shows the gauge circuit. You will need an ohmmeter to figure out which one(s) are grounded. Shout if you need help diagnosing further.

 

+1.

Violet wire will be 12V if dash cluster connector disconnected from dash.

[Mach1 Driver 560]

11 hours ago, Midlife said:

+1.

Violet wire will be 12V if dash cluster connector disconnected from dash.

Yes, that's true Mid, he did say there are no gauges yet (I need to pay more attention), so its a no load condition unless there is a short to chassis. Follow it back to the ignition switch and check for a bad connection, wire, ignition switch- or a dead battery.

[Midlife 814]

Violet wire ends up either at the ignition switch connector or at an OEM splice just above the ignition switch plug.  On almost all harnesses that I refurbish, I find higher resistance at the dash cluster connector, and 90% of the time, resistance drops to 9.5 ohms or so after recrimping the pin.  The other 10% are resolved by tugging on the violet wire at the OEM splice or the ignition switch connector (69's can be recrimped; 70's cannot).

[Mach1 Driver 560]

1 hour ago, Midlife said:

(69's can be recrimped; 70's cannot). 

Oh, that's too bad, he has a 70. So in this case you would replace that line when you refurbish a 70 harness? Phil, you better get in contact with Mid:, he'll fix you up: http://midlifeharness.com/ 

[Midlife 814]

The only way to repair a bad pin at the ignition switch connector itself is to replace the connector with pigtails.  You can't just remove the pins (bad design for sure!).

[philip arthur 0]

i got it down to the fuel gauge is drawing the juice. i get 12.3v to ivr with 5v coming out with all gauges unhooked. then conected  oil &temp gauges stayed at 12.3 v .I  diconeceted fuel gauge with oil and temp hooked up ,stayed at 12.3v to ivr. what do i do with fuel gauge.

[Mach1 Driver 560]

Disconnect the fuel gauge. Use an ohmmeter from chassis to each gauge post- it should be infinite ohms. If it isn't then check that the gauge posts aren't touching the panel and adjust its position if necessary. There is a possibility that the gauge has a short to chassis, in which case you need a new gauge. The line that runs to the fuel sender may have a short to chassis. Disconnect it at the tank and gauge then test with the ohmmeter from chassis to the wire- it must have infinite ohms. Lastly, it could be a short to chassis in the fuel sender.

[philip arthur 0]

when i tighten the gauges to the metal dash through the printed circut board  all posts read 14.5 ohms. when i have the gauges loose they will read u/l. can i put 2nd nut under the printed circut board to tighten the gauges and then put circut board on top to try and center the posts better?  with the printed circut board taped out of the way i can tighten up the posts and they stay o/l ohmes on booth gauges.

[Mach1 Driver 560]

4 hours ago, philip arthur said:

1.when i tighten the gauges to the metal dash through the printed circut board  all posts read 14.5 ohms.

2. when i have the gauges loose they will read u/l.

3.can i put 2nd nut under the printed circut board to tighten the gauges and then put circut board on top to try and center the posts better?

4. with the printed circut board taped out of the way i can tighten up the posts and they stay o/l ohmes on booth gauges.

1. From the metal housing to the gauge posts?

2. Again- from where to where? With the ohmmeter leads touching each other what does it read? And when they are separated it reads u/l?

3. You'll need to find someone familiar with the assembly. I've never had mine apart, but have read many cases where a post contacts the metal housing and shorts out.

4. From the metal housing to the gauge posts?

 

[philip arthur 0]

when i tighten the gauges to the metal dash through the printed circut board  all posts read 14.5 ohms. when i have the gauges loose they will read u/l. can i put 2nd nut under the printed circut board to tighten the gauges and then put circut board on top to try and center the posts better?  with the printed circut board taped out of the way i can tighten up the posts and they stay o/l ohmes on booth gauges.

 

put the gauges together afew more times . attched to the car it did not draw the volts.iwill hope it is working. big thanks for your help!