Dometic generator by Generac

[ken mccord]

Engine runs but no output. Cannot find a circuit board. Came out of a 1987 motorhome.

[EricWood]

more details, please.

Brushes yes/no?

No circuit card--any capacitors on the generator?

What size generator---in watts?

Some small gensets had an MOV across the rotor sliprings, usually imbedded in some plastic at the end of the shaft. If shorted, will drag volts down to nothing. (many gensets do not have an MOV)

Did it work before//has it not ran for a long time?

Done any welding on the chassis since last running it?

What have you checked so far?


eric

[ken mccord]

I checked the brushes and they looked okay. it is a 4500 watt. It has been sitting for a long time. I could not find any kind of circuit board anywhere.

[K D Redd]

Try "flashing" the feild at the brushs with some DC while the engine running. Flashing is using a battery to momentarily appling some energy to the field. You just want to apply the DC for a instant. Sometimes you will get a litle arc or a Flash. If the residual magnetic field is low this will return the generators function.

Kent

[ken mccord]

I did flash it using a method I found online using 3 60 watt light bulbs. Still no luck

[Jim Rankin]

Did that method use DC or AC power?

AC won't help, it will remove any residual if applied to the field.

[ken mccord]

It was AC, I plugged one end of an extension cord into the generator ran the black wire through 3 60 watt bulbs in a series and with the generator running I plugged the other end into a house outlet.

[ken mccord]

How do I flash the field using DC current

[K D Redd]

Momentarily connect 9 to 12 volts dc to the brushs with the engine running at it's rated RPM. I have heard of people using a 9 volt radio battery. I use a 12 volt and a couple of wire leads with probes on one end and battery clips on the other.

Kent

[Don Smith]

Please give the model number of your unit. I have the manual for a 4.5 kw unit that might help Send me an email Don

[Gecee123]

Is there Circuit Resets on the front? i made that mistake too once.. just a thought

[ken mccord]

my dometic 4500 watt generator has power when it first starts up but power output stops within a second after it starts running

[ken mccord]

I flashed the brushes using 12 volts, I have power as long as I am flashing the field but as soon as I remove the 12 volts my output stops. Also on initial startup I have power for just a second then I lose it. When I rev the motor I get a small amount of power approx. 3-4volts. Is there any way to check the voltage regulator or the small transformer.

[BTPost]

You likely have a Blown Bridge Filed Rectifier and are not producing Field Current except for some residual on initial Startup. Check the Field Rectifier.

[ken mccord]

Thanks, how do I check the field rectifier.

[Kendas]

Ken,

Before you try that have the regulator tested... The 4.5 kw Dometic (DTXP45?) is the same as the Generac TXP45 in a different wrapper as far as I know. My TXP45 had a "slightly" better version of the same problem where it would initially start to provide volts and then fall off to between 4 and 45 volts. Sometimes after starting/stopping a couple of times it would work correctly until the next time I tried it. Eventually it quit ramping up the voltage at all.

I pulled the control board and sent it to Flight Systems who checked it for $25 and found that it was fine. The only thing left was the regulator which I got from Advanced Service And Parts (ASAP) http://www.partsfortechs.com/asapcar...tor-p-258.html


The actual genset model number is on the data plate that is on the alternator itself. You can see a sample of a Dometic one in the link above.

If it is the same as the TXP45 I have the manual and can e-mail it to you... Send me a PM.

Another Ken (lot of us huh?)

[ken mccord]

Replaced circuit relay and I now have power but it is low.

[ken mccord]

I checked the field boost module and it had 12v going in but only 5v coming out going to the brushes. Im assuming this needs to be 12v going to the brushes. Can I bypass this since Im having trouble finding one.

[ken mccord]

I still have low voltage. I have 12v going to the field boost module but only 5v coming out and going down to the brushes.I have good power on initial startup but it only lasts a second. I have replaced the circuit relay module and built a new field boost module but still no luck. If a jumper from the battery down to the brushes the power picks up.

[peter s]

This sounds like the field is shorting out