[Roadsters] Instrument regulator test

[Pete Peters]

My voltage regulator pulses when I did this test, but it's pulsing up to
22VDC. Dunno how it's doing that with a 14.4VDC source. Perhaps the digital
multimeter cannot compensate quick enough for the pulses - perhaps not.

Does this mean the gauge VR is failing?

Pete

-----Original Message-----
From: datsun-roadsters-bounces at autox.team.net
[mailto:datsun-roadsters-bounces at autox.team.net] On Behalf Of John F
Sandhoff
Sent: Saturday, October 18, 2008 10:31 PM
To: Gary Boone
Cc: Datsun Roadster List
Subject: Re: [Roadsters] Instrument regulator test

On Sat, 18 Oct 2008, Gary Boone wrote:
> ...I've pulled the regulator out and want to test it before just 
> finding a new one...  How does one bench test this regulator?

Connect a voltmeter - or a small (like a dash light) 12 volt bulb to the
case and to one of the connectors. Then connect 12 volts (polarity does not
matter) to the case and the other terminal.
You should see voltage (or the lamp will light) for a few seconds, then it
will go out. A few seconds later, the voltage MAY come back on.

For these results to be accurate, you must have the voltage indicator
connected BEFORE you apply the voltage.

If you NEVER see voltage: The regulator is open (i.e. no good).
You MAY be able to open it and clean the contacts, but it probably won't
last.

If the voltage PULSATES (on... off... on... off...) the regulator is GOOD,
and you have it wired correctly (the terminal you applied voltage to
connects to the 'hot' lead from the ignition switch).

If you get voltage ONCE and then it stays off, you have the regulater
connected backwards. Disconnect power, Move the indicator to the other
connector, apply voltage to the now-available connector and you should see
on... off... on... off...

Important troubleshooting tip: If your gauges momentarily start to move when
you turn on the key and then drop back to zero, and you've been mucking with
the wiring, you probably connected the regulator in backwards.

If your gauges read way too high, possibly off the scale, the regulator is
either bad... OR the ground is bad. Unscrew it, clean the screw, case, and
body contact point (small wire brush) and reattach.

"next lesson will be on how this simple box acts as a temperature
compensator so the temperature-sensitive electric gauges are
(relatively) accurate regardless of it being zero degrees or a hundred
degrees" (or check the archives :-) ). In other words, you can't just
replace it with a constant-voltage regulator.

-- John
     John F Sandhoff sandhoff at csus.edu  Sacramento, CA
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