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Discussion Starter · #141 ·
And POOF! You're done!

Thank goodness I have a whole house genset from Generac I got a free gas powered Generac spray washer too.

Ha ha! It just started for it's weekly test.

*******************

Thanks for the reply.


I thought about going that route but, figured if I was totally demolished that I could possibly transport my gen to a new destination and power up.
 

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Discussion Starter · #142 ·
I had a thought..........If a gen looses it magnetic "charge", could a very strong magnet be placed onto the side of the stator(?) to induce magnetism to enable it to power-up"??
 

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Hey so I realize this is a somewhat old/dead thread, but its already helped me a great deal so I figured it would be a good place to start since it's abandoned.

I have the little brother to the generator in this thread, 5500w. Visually almost identical.

Here are some details:
  • Genny was overvoltage, so replaced stock AVR with same part number from this thread, since turning the potentiometer didn't have any effect.
  • Followed the same tutorial and made same harness to adapt. Verified harness connections are as they should be.
  • Rotor and stator measurements match those taken by the OP.
  • Upon replacement of AVR, generator was pushing only 55v.
  • Adjusted potentiometer on new AVR and completely lost power.
  • Tried flashing Rotor slip rings using 6v battery.
  • Tried flashing when on by reversing drill (and also tried in forward)
  • When completely disconnected AVR and given 12v to brushes, I get close to 60v ac.
I would appreciate any extra troubleshooting steps you may be able to offer. Im leaning toward a defective/DOA AVR but would like to verify. Thank you!
 

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So did some additional diagnostic on the AVR and it seems like it did arrive defective, or was destroyed upon startup.

This makes me wonder:

1)Is there any chance that a defective rotor or stator could have caused it?
2)if yes to the first question, is there some tests I could run to determine that, or did the tests described above fully determine the windings are good?


Hopefully someone out there is still watching this thread! :unsure:
 

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Did some more testing. Seems the rest is fine. Using a multimeter was able to determine there is no short or open circuit in the stator or rotor windings. Compared all values against a known working unit. Swapped in the OEM AVR from that unit and it's also working fine. The replacement arrived DOA.
 

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Did some more testing. Seems the rest is fine. Using a multimeter was able to determine there is no short or open circuit in the stator or rotor windings. Compared all values against a known working unit. Swapped in the OEM AVR from that unit and it's also working fine. The replacement arrived DOA.
While you are working out of my experiences, your troubleshooting skills are great. Let us know what happens when the new AVR comes in.
 

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Hey update incoming!

I removed the defective AVR in order to determine what part of the circuit has failed. I figured it was either a diode or the BU931T NPN transistor. As it turns out, I was right on both at least one count. 1x1N4007 (out of 6) failed. I have already replaced the diode. The NPN transistor is a darlington type and cannot be tested without a test circuit or specialized equipment. I dont want to invest that much time when the component isn't very expensive and can be simply replaced.

Problem - Only China seems to have them, and there is some sort of export embargo to Canada at the moment from China. Fastest lead time is at 16 weeks atm.

Anyone have ideas on how to get one? I have tried:

Local suppliers
Google
Amazon
Ebay
Google results

It seems nobody in NA stocks them, including Amazon and eBay sellers. I found one in Japan, and another in Russia (both from amazon). Hoping someone here may have resources to get them sooner. Thanks everyone!
 

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You can just make one. A Darlington pair is two BJT transistors. The emitter of one feeds the base of the other. The collectors are connected together. It’s a common lab in engineering school for teaching about transistors. No Chinese whatever needed.
 

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Thanks for your reply! It's a good idea. I've attached the datasheet for this component. According to the schematic, there are 2 diodes as well as 2 resistors in the package. Unfortunately the sheet doesn't detail the resistors values. Without creating the test circuit, are you aware of a way to measure the values of each resistor?

Thanks in advance!
 

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Ok so, ordered the bu391t from Amazon. It will probably show up some time in 2023 lol.

While waiting, I tested the circuit components in further detail:
  • KSP44 BJT NPN is shorted and allowing bidirectional current flow across all terminals.
  • Mpsa05 BJT NPN is shorted across C+E allowing bidirectional flow.
  • Replacements ordered

The goal of the above is to repair the old board to have a spare in the event of failure of another avr, without having to order replacements each time.

In the meantime, I received a replacement AVR. It is also working, and the unit is working. Voltage output is a nominal 124 at idle, and maintains such with 1000w of electric load.

I'll follow up on the avr repair once all components have arrived. Likely in 4 to 6 weeks.
 

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Hey everyone. The bu931t arrived from China. I replaced it after having previously replaced the other 2 transistors, and one diode.

We have power!

I'm going to attach the schematic of the Coleman AVR 52627, which is also ICM part number AB3101-240.

While waiting for these parts to arrive, I also managed to get another one of these units to replace/repair the AVR. This is going to be part number 0065649SRV, which is the Generac replacement part for the previous AVR (0052627, and also 0052795). This one has a varistor that overheated and opened. Going to continue the inspection on that one. I have also attached the schematic (rev3) for the new Generac 0065649SRV.

I hope this information can be helpful to someone.
 

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