Voltage Regulator.... what do I have?

targa44 · 09-11-2013, 11:29 AM

... no specific issues, but I don't know what I have.

Attached some photos and hoping to get educated. It's for a '73 with a Euro 3.0 CIS. My tach bounces a little with shifting, but settles down - so, my question is attempting to know what I've got. (actually, hoping I'm showing the right part)

thanks,

timmy2 · timmy2's Garage

Looks like a replacement unit with an adjustable rheostat. Doesn't look like the original for a '73 at all. Is there any identifying information or stamping on it at all?

timmy2 · timmy2's Garage

If you want to see if the VR is causing trouble pick up a lighter socket digital voltmeter and plug it in and watch it while you drive. Could be the tach is sticky.

targa44 · 10:34 PM

Dennis,

....thanks for responding to my PM as well and taking the time to comment. You've been a great resource to me and the board.

... no marking except "049" black stamp on the side and on the little blue square on back it might be "BOURNS-3386" arching around the white button, but I'm just not sure - too small.

I'll get that little meter for the cigarette lighter and monitor that, but mainly, I just wanted a back up VR --- without having to pull the fan housing out and see what the gen/alternator is.

thanks,

kugelfischer · 09-11-2013, 10:53 PM

Hi KJ.
+1 on checking your voltage, however this isn't likely to be your problem.
Do you have your original '73'tach in the car?
First, if its original the input impedance may not be matched correctly given the engine swap. Are you running a newer 6-pin or original 3-pin CDI box?
Second, the internal "damper" in the tach may need refreshing. I had the same problem. Try taking it to Palo Alto Speedometer to have Hartmut check it out. If it needs a rebuild, the cost is only about $100. He can also swap out the internal circuit board for a more modern version that will work better with your potentially updated ignition system.

Good luck!

db_cooper · db_cooper's Garage

That is an aftermarket adjustable VR. Many were sold to replace the Bosch VR back in the day.

Porsche had a product circular about using the later model alternator with the internal voltage regulator on the early cars with an external regulator. Some basic wiring changes and a delete of the VR on the driver's side engine fusebox. I have it somewhere in the archives if you decide to go that route.

The updated alternator/internal regulator change really helped charging when used in the early cars.

Be sure your ground strap on the back of your alternator is in good shape, clean and secure. When that ground gets old, the charging system really will not work well.

targa44 · 09-11-2013, 11:38 PM

Kugel.... yes, I believe it's the orig. tach, but I don't think the CDI 3-pin would have been - it's an early '73. It's likely from the '76 Euro - 930/02. I'll try and contact the prior owner about the pieces and method behind the conversion.

db... thanks for the VR info and suggestion. I've certainly thought about that, but things are currently hanging in there... the bouncing is short lived for now and not too distracting.

thanks,