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ag tronics 4kw no output

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larryr

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i have a 4kw 8hp agtornics gen set that has no ac output . this unit has a rotor with four slip rings. two rings feed the ac plugs. and two appear to feed a bridge rectifier that provides dc to the fields. there is no voltage reg. i assume that the rpm controls max voltage. i have checked for opens and grounds and have found none. the rectifier checks ok. i can power the rec with 120v ac and it has a dc output. i have researched utube for similar problems and it seems that its a co common occcurance for the unit to lose residual magnetism and stop outputing. i have tried the spin the drill backwards technique with no results. any ideas? coleman bought ag in the eightys but their service has no tech info on this unit larryr
 
I'm not familiar with the gen, but are the slip-ring brushes in good order (e.g. adequate pressure on the slip-rings) ?
 
no output 4kw ac tronic

I'm not familiar with the gen, but are the slip-ring brushes in good order (e.g. adequate pressure on the slip-rings) ?

thanks for the reply. yes my brushes and slip rings are in as new conditon. i can detect a small amount of magnetism at the rotor i have installed a new rectifier. still no output. if some one out there is familiar with the four slip ring design and how to properly trouble shoot it i would be grateful. larryr
 
Have you checked the continuity between the slip rings? Maybe a wrong pair of slip rings are being tapped .....

Ramesh
 
it seems that its a common occcurance for the unit to lose residual magnetism and stop outputing.
Is it possible to re-introduce some magnetism, e.g. with a small permanent magnet or by temporarily passing current from an external DC source through the coils?
 
ramesh, i have checked continuity between the slip rings, they all have approx 2ohms between any two rings. your comment about tapping the wrong rings is a possiblity, but i dont know how to check for that. i was hoping that someone on this forum might have some experience with this type of system and be able to tell me how test the circut.the four slip rings have me confused. thank you larryr
 
Disconnect the connection to the bridge rectifier (feeding the field) and check for any voltage(s) between the rings. It cannot / should not be Zero.

It could be a 3 phase alternator but 2 Ohms between any 2 rings is odd. Can you get more accurate values?

Ramesh
 
Given how you explain the design of the Agtronic generator's alternator, it sounds very similar to those from Winco or Gillette although sets with slip rings, diodes and a rotating field, usually don't employ brushes- hmmm. You might want to look up those brands to see what's offered on troubleshooting that style of alternator. With no regulator circuitry aboard, those units make for highly reliable and stable output units. About the only thing that typically failed were the rings or diodes. There are power generator forums on the net you can join for advice & assistance.
 
In most cases you may find:
1. A winding for regulation similar to an alternator. Current induced here changes the voltage.
2. A winding that is designed to produce a very small amount of DC with #1 turned off.
The #2 is the "kick" for #1. There has to be residual magnetism to get the control circuit up an running.

3. The oil sendor switch, No oil, no output.
4. Frequency is changed by the RPM. Not in range - no output.

5. Output windings, 120, 240, 12 V

Usually the control winding needs to be kicked with a 12 V supply in the right direction, so it's a quick connect to +12 at high current that magnetizes the field.
 
Low oil switch should only shut down the engine by disconnecting the ignition circuit. It shouldn't be wired to anything in the alternator. I'm assuming his engine works but the generator itself doesn't.
 
Perhaps you could apply AC to the bridge rectifier (rectifier brushes removed or disconnected) to power to the fields while it is running and see if you get an output on the other slip rings. It would be best if you could apply an adjustable AC voltage such as from a Variac.
 
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