how to test a voltage regulator

[cuda hunter]

So, how do I bench test a voltage regulator?  I have a box of them.  Probably 12 or more.  Not sure what's good and what is not good.   Any idea how?  the parts stores don't know now to test them.  Only if they are internally regulated in the alternator. 

[JS29]

@cuda hunter I will ask a friend of mine who retired from owning a parts store in the morning. Your car is older than the counter people!     Probably asked what a barracuda was. been there done that. 

[cuda hunter]

yeah, they are a little lost.  And the one old guy is off until later. 

[JS29]

You are working on a 67, How meany wire VR do you have? What is it at the battery for voltage when it is running. How meany wires at the plug for the VR?

[cuda hunter]

yeah, the 67.
I have 12.54 not running and 12.24 running.
Battery must be low, but it's a gel and I hate charging them as it seems they die easier.

It's a two black wire VR. 

[soundcontrol]

I have a few that I wanna test also, I searched for info and found a bunch of YT videos, have not had the time to go thru them yet, but here is one that looks correct. The post-70 2 wire model has ignition on one (top) pin, and will control the alternator by grounding one of the field connectors, the other one has ignition 12V.

Pre -70: One field on alternator is grounded and VR control the positive field to the alternator. (Not this test)

[cuda hunter]

Ok, so what is the box with the gauges on it?  I don't have that one. 

[soundcontrol]

Ok, so what is the box with the gauges on it?  I don't have that one.

It's an adjustable DC power supply, you can turn that dial and adjust the output. You don't need a fancy one for a test, this cheap one will do.
You just need to produce between 12-16V range about to see if the VR works.
You have to cut and split the output cord on it. (There is tons of different ones on e-bay that will work).
You do need a good voltmeter though.

https://www.ebay.com/itm/AC-to-DC-Adapter-1-24V-Adjustable-Volt-Power-Supply-Motor-Speed-Controller-Tool/352852620673?hash=item5227a7b581:m:mHcTElM_yM01SzzkCRBnQpA

[soundcontrol]

My new Barracuda dosen't charge at all either, gonna test the VR soon. Let me see if I can figure ut a way to test the VR without the fancy tools.

I did a quick test of the alternator, no regulator, no wires connected, + to 1 field, alt.output to battery, left the field wire that goes to the VR open, measured voltage on battery while I grounded the other field wire, (quickly, not leaving it connected long) no difference, that indicates a broken alternator.
If I ground the field that goes to the VR I should have full output from the alt.
Gonna take it apart some day.

[dodj]

I have a few that I wanna test also, I searched for info and found a bunch of YT videos, have not had the time to go thru them yet, but here is one that looks correct. The post-70 2 wire model has ignition on one (top) pin, and will control the alternator by grounding one of the field connectors, the other one has ignition 12V.

That looks like it should work. Then read the resistance to gnd of the field wire?

[soundcontrol]

I have a few that I wanna test also, I searched for info and found a bunch of YT videos, have not had the time to go thru them yet, but here is one that looks correct. The post-70 2 wire model has ignition on one (top) pin, and will control the alternator by grounding one of the field connectors, the other one has ignition 12V.

That looks like it should work. Then read the resistance to gnd of the field wire?

Since the testlight is on or off att a certain voltage, it seems that the VR works more like a relay. Simply grounds the field wire. Not 100% sure, but it looks that way.
I always thought it was more to it, never really investigated it.

[JS29]

@soundcontrol  That is what was explained to me. 14.2,14.3 is ideal voltage at the battery. 

[soundcontrol]

@soundcontrol  That is what was explained to me. 14.2,14.3 is ideal voltage at the battery. 

Yep, seems right, that when the VR kicks in and prevent the alt. from going higher.

[dodj]

I have a few that I wanna test also, I searched for info and found a bunch of YT videos, have not had the time to go thru them yet, but here is one that looks correct. The post-70 2 wire model has ignition on one (top) pin, and will control the alternator by grounding one of the field connectors, the other one has ignition 12V.

That looks like it should work. Then read the resistance to gnd of the field wire?

Since the testlight is on or off att a certain voltage, it seems that the VR works more like a relay. Simply grounds the field wire. Not 100% sure, but it looks that way.
I always thought it was more to it, never really investigated it.

Designed more like a relay than a variable resistance would be similar to the dash voltage regulator which is just an on off switch....Makes sense given the tech at the time.

[soundcontrol]

I tested my VR's now, I had 5 of them, 2 worked, 2 broken, 1 went missing (!).
I tried to find a way to test them without the adjustable power supply, but I failed (I have a power supply but I wanted to see if I could do it without one).

It should work with 10 regular AA batteries instead, that makes 15 volts (and the test light should be off), then remove 2 of the batteries
and we're down to 12V and the test light should be on. Not an exact science but at least you can see if it works.
The problem was that I could not string 10 AA's together in an easy way.

Mine turned off at 14,8 V, both of the working ones, (should be 14,2V).