# Honda EX500 electrical fault



## Waterworks (Dec 9, 2020)

I have an ancient 240v EX500 the type with the pressed tin outer case, it was in use all last winter but this year is only putting out 100 v / 120 v on max revs, im only familiar with AVR / brush or capacitor regulated alternators, not sure what kind this is exactly? 

I need to test the windings upstream of the regulator unit but have no specs to go on. I'm guessing if half the voltage is gone it could be diodes ( if it has any ) ?

Anyone got a service manual download for this model ?


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## tabora (Sep 6, 2018)

Waterworks said:


> I have an ancient 240v EX500


I don't find an EX500 listed. Do you mean the EX5500?


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## iowagold (Jan 22, 2020)

Waterworks said:


> I have an ancient 240v EX500 the type with the pressed tin outer case, it was in use all last winter but this year is only putting out 100 v / 120 v on max revs, im only familiar with AVR / brush or capacitor regulated alternators, not sure what kind this is exactly?
> 
> I need to test the windings upstream of the regulator unit but have no specs to go on. I'm guessing if half the voltage is gone it could be diodes ( if it has any ) ?
> 
> Anyone got a service manual download for this model ?


Set the rpm to 3750 rpm.
*click here for the test equipment page*


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## Waterworks (Dec 9, 2020)

tabora said:


> I don't find an EX500 listed. Do you mean the EX5500?


Listed as EM500 outside Europe. It's 400 w suitcase job.


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## tabora (Sep 6, 2018)

Waterworks said:


> Listed as EM500 outside Europe. It's 400 w suitcase job.


Aha... Our EM500 is a 120V only generator. And your 230V nominal power works differently than our 240V split phase. On the EM500, it would be the AVR assembly that would most likely be at issue, or possibly the diode assembly... I think this is your diagram:





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## Waterworks (Dec 9, 2020)

Ft


tabora said:


> Aha... Our EM500 is a 120V only generator. And your 230V nominal power works differently than our 240V split phase. On the EM500, it would be the AVR assembly that would most likely be at issue, or possibly the diode assembly... I think this is your diagram:
> 
> 
> 
> ...


Yes that looks the same, I need a wiring diagram for this specific model.


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## tabora (Sep 6, 2018)

Waterworks said:


> Yes that looks the same, I need a wiring diagram for this specific model.


Here's an inexpensive opportunity: HONDA EM500 / EX500 GENERATOR SERVICE AND USER MANUALS ON CD + DOWNLOAD | eBay


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## Waterworks (Dec 9, 2020)

Ok, i have read up on brushless exiter alternators and have got the basics of how they work. I should be able to test if the AVR is getting the DC voltage from the rectifier. 

If the AVR is the fault I don't think any spares exist so it will be impossible to repair.


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## tabora (Sep 6, 2018)

Waterworks said:


> If the AVR is the fault I don't think any spares exist so it will be impossible to repair.


There are no new ones, but likely there are used units from EX500s that died from some other reason. Did you get that inexpensive service manual? Worth its weight in gold.


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## Waterworks (Dec 9, 2020)

tabora said:


> There are no new ones, but likely there are used units from EX500s that died from some other reason. Did you get that inexpensive service manual? Worth its weight in gold.


The seller has even discounted the price for just the download, but I'm already in contact with Honda and just waiting for them to confirm they don't have this manual for free. 

If the AVR has died then it's not even worth buying the manual at any price because it's unlikely an AVR unit will be found ( I'm in the UK )

The only hope I can see is if they used the same AVR on other models that still have spares available.


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