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Porter Cable BSV 750-W Brushless Generator with NO AC output

joehelf

Registered
I'm back from vacation.
I have confirmed the diodes on the rotor are good. I used a 12V light to test with the diode in series. The light lit up with the diode in one direction but not in the other direction. I soldered the diodes back in just as they were before removing.
I also tried to flash the exciter windings (I'm calling these the 2 wires going to the CAP) with a 12V battery and a 10amp fuse in series. I only held the battery on the lead for about 2 seconds. When I pulled the battery power off the exciter lead it sparked but did not blow the fuse.
Then I tried flashing the AC leads to the bridge rectifier for the 12V dc posts on the front panel. This flashing blew the 10 amp fuse. I then checked these leads for continuity and it was still reading Ok, about 1.2 ohms.
No change. Nada. Zilch.
I did the flashing with the generator not running.
I just wanted to touch base with any of you that might be following the thread.
 

Jim McIntyre

Subscriber
Last Subscription Date
07/10/2019
Hmm. I suppose the capacitor might be bad. I know you tested it, but caps can fail in ways that might test OK, but not work. Not likely, but possible.

Other than that - all I can think of is a shorted turn somewhere in the generator, which basically renders the set scrap...
 

joehelf

Registered
Here's a question about ohms readings.
The technician from Porter Cable told me the stator windings should read about .130 -.145
If my meter is showing .3 -.4 ohms is that too much ohms?
He said that didn't sound bad.
The pink or red wires going to the CAP are right on at 1.2 ohms.
The rotor wires are supposed to read 1.43 -1.53 and I think they are reading a little higher too. Around 1.9 ohms.
Is this just the fact that perhaps my meter can read that accurate that low?
Joe
 

Jim McIntyre

Subscriber
Last Subscription Date
07/10/2019
...Is this just the fact that perhaps my meter can't read that accurate that low?
Joe
Yes - take the two meter probes and hold them together. You'll see that your meter doesn't read exactly zero. The meter measures all the resistance in the circuit, including that in the probe wires, which is typically a few tenths of an ohm, but varies quite a bit depending on how clean the probes and connectors are, and how hard you squeeze them together.

There are ohmmeters that are capable of reading very low resistances very accurately. They'd have 4 wires to connect instead of just 2.

http://www.allaboutcircuits.com/vol_1/chpt_8/9.html
 

Joe Romas

Subscriber
Age
76
Last Subscription Date
10/03/2019
Joe
I think you mentioned on page 1 that you had an AC voltage reading o2 2 volts. I've played with some of these inexpensive units and that low voltage has always been an indication the 2 diodes circled in green on post #16 were bad. Also I've seen a Square bridge rectifier used in placed of the 2 diodes. with those diodes bad there's no excitation voltage being produced.
They also don't need flashed, they're called "self exciting" for a reason and that's because there's a small magnet epoxied to the rotor.

Another Joe
 

joehelf

Registered
But Joe. I've tested the diodes every way I can think of. Can the small magnet you mentioned lose its magnetism? According to all I've read the CAP is what causes the excitation. I found the literature from the U.S. patent office that describe how in theory these are supposed to work. I don't doubt anything or anyone. I just can't find the problem. I'm thinking about buying a new CAP and just put it in and see what happens.
 

Joe Romas

Subscriber
Age
76
Last Subscription Date
10/03/2019
Joe.

The small magnet is working because your getting one or two volts AC. That should get it started producing 120.
Getting a new cap might be a good idea, if it does not cure the problem at least you'll have a spare.

Joe
 

mariano

Registered
Re: Porter Cable BSV 750-W Brushless Generator does not turn off completely

Hi, Has anyone had the problem that when trying to turn off the generator, it just continues to idle very low and sputter? Any ideas on what can be wrong with it? Thanks
 

Joe Romas

Subscriber
Age
76
Last Subscription Date
10/03/2019
Re: Porter Cable BSV 750-W Brushless Generator does not turn off completely

Hi, Has anyone had the problem that when trying to turn off the generator, it just continues to idle very low and sputter? Any ideas on what can be wrong with it? Thanks
The OFF switch should ground a lead going to the magneto coil and kill the spark therefore stopping the engine.
 

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