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Old 03-15-2017, 11:32 PM   #1
RED72blazer
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buzzing external voltage regulator 72 K5 blazer

Alright, in my 1972 blazer recently my charging system was overcharging. I traced it to a bad regulator. Replaced it. It charges fine. But there is a loud buzzing coming from my new regulator. Figured it was a bad new part. Replaced it. Still buzzing. Went to another brand. Still buzzing. So now just because. I changed the alternator. Still buzzing. Then I got a 80 dollar ac Delco regulator. Still buzzing. Today I cleaned all the grounds. Still buzzing. Anyone have any ideas on what is going on? This is getting tiresome. I do have a new wiring harness from M&H. I've had zero problems in 10 years or more with the stock system. I do not want to go to a 1 wire alternator or internal regulator. I just want the stock system to work. Any help would be great. Thanks
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Old 03-15-2017, 11:52 PM   #2
VetteVet
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Re: buzzing external voltage regulator 72 K5 blazer

Do you have the regulator grounded to the sheet metal and to the alternator?
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Old 03-15-2017, 11:57 PM   #3
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Re: buzzing external voltage regulator 72 K5 blazer

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Originally Posted by VetteVet View Post
Do you have the regulator grounded to the sheet metal and to the alternator?
The alternator and the regulator both have the "factory" grounds installed. I even ran a temporary wire between the 2. No difference.
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Old 03-16-2017, 12:24 AM   #4
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Re: buzzing external voltage regulator 72 K5 blazer

Are you hearing the buzzing in the regulator or in the cab with the radio on. The condenser on the VR must be hooked up or you will hear the buzzing in the radio.

Here are some threads on the buzzing that might solve your problem.
https://www.google.com/search?domain...D%3A1%3B&hl=en
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Old 03-16-2017, 12:30 AM   #5
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Re: buzzing external voltage regulator 72 K5 blazer

No radio installed currently. It's definitely the regulator. You can feel it if you put your hand on it.
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Old 03-16-2017, 12:06 PM   #6
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Re: buzzing external voltage regulator 72 K5 blazer

The buzzing is caused by the points in the regulator opening and closing at a very rapid rate more than normal probably due to the voltage sensing circuit for the alternator. This would be the blue wire to the alternator and the red wire from the regulator to the soldered junction. Or you may have just gotten another bad regulator.

Silly question: did you re-install the regulator using the little rubber washers? I know, but I have to ask.

A very good option would be the solid state regulator made by Wells which is sold at Napa and Autozone PN. VR 715 for pre 73 GM vehicles. Here is a good thread on another forum about it.

http://www.chevelles.com/forums/45-c...-60s-cars.html
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Old 03-16-2017, 05:40 PM   #7
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Re: buzzing external voltage regulator 72 K5 blazer

............

http://www.autozone.com/batteries-st...e&newYmme=true
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Old 04-05-2017, 05:48 PM   #8
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Re: buzzing external voltage regulator 72 K5 blazer

Okay. Maybe I wasn't clear. I understand how the voltage regulator works and what is making the noise. The fact is, it's shouldn't be making that noise and if I let it go, it burns up the regulator. I do not think that switching to another style regulator will help. It will burn up too.

What I am wondering is what is causing all this to happen. Obviously something is wrong. Honestly I could live with the buzzing. But I need it to stop burning up regulators.
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Old 04-08-2017, 01:33 PM   #9
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Re: buzzing external voltage regulator 72 K5 blazer

Sorry I missed your repost. I covered most of the common reasons for the buzzing. It appears that your alternator and regulator are OK and the wiring harness is fairly new.
This leaves a wiring issue or a possible short to ground in the charging circuit that is not fused.This short may be throwing the alternator into a full charge output mode and if the short is intermittent it will cause the alternator to cycle between normal and full charge.

Another possibility is that the blue and white wires from the regulator are not making a good connection on the alternator end or the regulator end. I would do a continuity check on those wires and also check for a full 12 volts on the red wire at the regulator plug. This is the sensor wire which tells the regulator what the system voltage is and lets it adjust the alternator output to compensate.

Check the voltage of the brown wire with the key on and with it off. 12 volts on and zero with it off.
Do you get a charging light or a flickering needle on the ammeter if you have a gauge dash?
A bad diode in the alternator could cause the regulator to buzz, If you disconnect the alternator plug does the buzzing quit? A shorted diode would be the short to ground I mentioned above.
A wells vr 715 is totally different to the points style and it is around $20 bucks. If everything checks out. It might be a solution.
Other part numbers for the solid state regulator are AC Delco # D663
and GM # 1119519. The sold state regulators shunt the excess voltage from the alternator to ground much like a Zener diode.

I know you want to stay with the OEM stuff but you wold be much happier with an internally regulated alternator.

Mid eighties 12 SI is the ticket.


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conversion wiring is very easy.


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Or you can even go to the newer CS style.


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the conversion is just as easy but you need to wire in a 75 to 300 ohm resistor.


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The brown wire goes to the L terminal and the red wire goes to the S terminal.
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