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-   -   Question re standby alternator (https://vansairforce.net/community/showthread.php?t=101559)

Mich48041 09-20-2013 08:44 PM

Bruno,
Remove the wire from terminal 5 on the voltage regulator and ground that end of the wire. Turn on the master switch. The lamp should illuminate. If it does, the above test proves that the circuit breaker and lamp are good.
If the lamp does not illuminate, further testing is required. I like to use a 12 volt test light similar to this one:
http://www.autozone.com/autozone/acc...er=186543_0_0_
Connect the test light clamp to ground and test the output of the circuit breaker with the test light probe. Of course the master switch needs to be on for this test. If there is voltage at the circuit breaker, then probe the lamp. If the lamp is getting power but does not illuminate, the bulb or socket could be bad. Do not replace the circuit breaker unless testing proves that it is bad.
Joe Gores

RV-4 09-21-2013 07:08 PM

SD-20 Light testing
 
Hi Joe

I did that yesterday and the light does come on if I press on it and I also tested both Circuit Breaker ( The one for the light ( 2 Amps ) and also the one for the field ( 5 Amps ) and both are working as they should...

I tested the alternator today in flight by pulling the breaker of the main alternator field so I could get the stand by to pick up the load and it did ( looking at the load on the amp meter ) but the light still did not come on to say the stand by was working .

Something I noticed today though was the voltage supplied by the SD-20 at 2400 engine RPM. The voltage was only 12.5, 12.6 volts and as far as I know the SD-20 should be providing something like 13.7 when used as a back up alternator.

Maybe the voltage regulator is set too low.. and the light is supposed to come on as 13 volts is I remember properly..

What do you guys think, anyone installed one and could confirm this.

If this doesn't work then I don't know what to think to be honest.I guess a call to B&C will be in order at that point.

Thank you for your feedbacks, greatly appreciated

Bruno

AltonD 09-21-2013 07:19 PM

Are you using the SB1B-14 regulator from B&C?

1. I found the lamp socket to not be reliable. I changed it out to a "Push to Test" socket from spruce. Works fine now. http://www.aircraftspruce.com/catalo...?clickkey=6309

2. If you are using the B&C backup regulator, it is set for 13 volts.

http://www.bandc.biz/pdfs/SB1B-14_Install.pdf

page 1, second Paragraph from the bottom. I had to tweak mine up a bit.

Mich48041 09-21-2013 09:27 PM

Quote:

I did that yesterday and the light does come on if I press on it and I also tested both Circuit Breaker
I do not understand. What did you do yesterday? Did you disconnect the wire from regulator terminal 5 and ground the wire? If so, did the light come on then? If so, then the problem is within the voltage regulator.
Where is the current sensor located? Depending on its location, it could be sensing battery discharge current and not alternator output current. Unless there is a very heavy load, a voltage of 12.5 indicates that neither alternator is supplying current. B&C can give helpful advice for checking out their products.
Joe Gores

RV-4 09-23-2013 10:28 AM

SD-20 TROUBLE SHOOTING
 
Hi Guys

Alton: I have the SB1B-14 regulator installed with the Hall effect current sensor installed as per B&C instructions.

I think I may have to adjust mine like you did with yours.

I will give B&C a call to confirm the wiring and the way it operates right now before doing anything..
------------
JOE
The current sensor is the one supplied by B&C and is fully assembled when you get it.
It is connect as per their instructions ( verified twice )so it shouldn't be the problem.
I will verified the wire from Pin 5 again when I go back to the hangar sometimes this week just to make sure.

I'll keep you updated.

Thanks

Bruno


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