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Onan 7.5JB - Wiring


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  #1  
Old 01-07-2017, 05:13:55 PM
kiteoregon kiteoregon is offline
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Default Onan 7.5JB - Wiring

So the PO on this unit tried to label the lines, but the labels are since gone. Some of the wires are tied together, here are the pairs:

L1 = T1 & T6
L2 = T8 & T10

Then T9 & T11 are tied together as well as T3 &T5

I want to wire to a 220 circuit.

So, which of the T9 or T3 pair would be equivalent to the common? For the ground i assume i would just connect the ground to the ground post in the electrical box.

Thanks
KO
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Old 01-07-2017, 06:02:07 PM
Max Thompson Max Thompson is offline
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Default Re: Onan 7.5JB - Wiring

900-0814 is the Yd gen-end manual you want. It has "re-connection" diagrams in it and an explanation about the neutral connection. This manual can be downloaded from the below linked site, thanks to Doug & Mike's hard work.

I assume this is the same JB you just had a fight with the points on, but without posting the model & serial numbers again we have to go back to your old thread to see if we can find that info. The data plate info will also let us find the build sheet & wiring diagram for your specific set.


http://www.twinslan.net/~n0nas/manuals/onan/
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Old 01-07-2017, 06:39:36 PM
kiteoregon kiteoregon is offline
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Default Re: Onan 7.5JB - Wiring

I will look this up...

7.5 Jb - Serial: A960597423 Spec: 68774E.

I could not find the one you referenced, is this the correct one: 0900-0186 Onan Mobile, RV & AUX Genset Wiring Diagrams (06-1989).pdf
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Old 01-07-2017, 07:50:43 PM
Max Thompson Max Thompson is offline
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Default Re: Onan 7.5JB - Wiring

Sorry, should have read #900-0184 . I will look up your build sheet & print.


Your print should be attached, it includes reconnection diagrams. Did not find the build sheet, maybe Kevin or MBB can locate it.
Attached Files
File Type: pdf 7.5 JB DIAGRAM 612-6650.pdf (149.4 KB, 46 views)

Last edited by Max Thompson; 01-07-2017 at 08:06:05 PM.
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Old 01-07-2017, 09:13:15 PM
kiteoregon kiteoregon is offline
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Default Re: Onan 7.5JB - Wiring

So now how do i read this schematic? This is to be wired into a DPDT breaker, so 1 phase, 220, 60 Hz. But from this i am not sure how to figure out what T wires are tied together to create a hot leg?

L0 = T2, T7, T4, T12, these are all connected to the post in the wiring box, this should be my common. Should i connect the ground to the common, or to the ground post on the back of the generator that the battery uses?
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Old 01-07-2017, 09:42:36 PM
MBB MBB is offline
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Default Re: Onan 7.5JB - Wiring

Here is the build sheet. I cant read the AC wiring diagram number.

Here is the heater diagram.
Attached Files
File Type: pdf 75JB68774E.pdf (30.1 KB, 27 views)
File Type: pdf 612-6642.pdf (158.6 KB, 17 views)
File Type: pdf 625-0023.pdf (36.5 KB, 26 views)
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Old 01-07-2017, 10:18:37 PM
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Billy J Shafer Billy J Shafer is offline
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Default Re: Onan 7.5JB - Wiring

It is wired for 120/240 single phase
2-4-7-12 is the common
The ground can go anywhere.
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Old 01-08-2017, 10:54:17 AM
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Default Re: Onan 7.5JB - Wiring

It looks like I didnt include the complete control wiring diagram. Here are all 3 pages.
Attached Files
File Type: pdf 612-6642-1.pdf (216.1 KB, 23 views)
File Type: pdf 612-6642-2.pdf (226.7 KB, 19 views)
File Type: pdf 612-6642-3.pdf (158.6 KB, 17 views)
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Old 01-08-2017, 11:56:29 AM
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Default Re: Onan 7.5JB - Wiring

Quote:
Originally Posted by kiteoregon View Post
So now how do i read this schematic? This is to be wired into a DPDT breaker, so 1 phase, 220, 60 Hz. But from this i am not sure how to figure out what T wires are tied together to create a hot leg?

L0 = T2, T7, T4, T12, these are all connected to the post in the wiring box, this should be my common. Should i connect the ground to the common, or to the ground post on the back of the generator that the battery uses?
IF you are using this to tie to a building's power system, the T2, T7, T4, T12 is NOT ground. It is neutral.
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Old 01-08-2017, 12:09:42 PM
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Default Re: Onan 7.5JB - Wiring

Yes ground and neutral are two different items.
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Old 01-08-2017, 04:13:12 PM
kiteoregon kiteoregon is offline
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Default Re: Onan 7.5JB - Wiring

Yes this is connecting to a house.

L1 = hot leg, black
L2 = hot leg, red
L0 = common, white

I still don't have any power output. I will read up and try to figure out what controls the output power. Once it's running, do i need to bring up idle or do anything to engage the load side? From the only gauge i have it appears to be charging the battery.
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Old 01-08-2017, 04:31:50 PM
Augie1 Augie1 is offline
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Default Re: Onan 7.5JB - Wiring

The generator should be running at 1800 RPM. Never apply or disconnect a load unless it is running At rated speed or you could see smoke. If it is running at 1800 you should have voltage close to 120/240 volts.
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Old 01-08-2017, 05:22:29 PM
kiteoregon kiteoregon is offline
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Default Re: Onan 7.5JB - Wiring

How do i determine what RPM the engine is running, is there a voltage to check or supplemental gauge i can get?
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Old 01-08-2017, 05:30:30 PM
Dale Russell Dale Russell is offline
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Default Re: Onan 7.5JB - Wiring

Get your self a "KILL-A-WATT" Meter. It will read Volt, Amps Hrtz. & etc. They are a very good investment with a generator of any kind.

http://www.newegg.com/Product/Produc...82E16882715001
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Old 01-08-2017, 06:23:26 PM
len k len k is offline
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Default Re: Onan 7.5JB - Wiring

Quote:
Originally Posted by kiteoregon View Post
I still don't have any power output. I will read up and try to figure out what controls the output power. Once it's running, do i need to bring up idle or do anything to engage the load side? From the only gauge i have it appears to be charging the battery.
Engine supposed to run at ~ 1800 rpm at all times, no-load and full load.
Rpm controls hz, electronic voltage reg on top of control box controls voltage.

IF bat charging windings are making power so too should your "120" VAC main windings. The voltage reg powers the rotor electromagnet which sweeps magnetic feild thru both "120" and bat charging windings.
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Old 01-29-2017, 03:15:52 PM
kiteoregon kiteoregon is offline
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Default Re: Onan 7.5JB - Wiring

On further investigation, if i place my volt meter on AC and connect to L1 with the red, and common with black, i only get 2.30 volts once warmed up. If i twist the idle screw on the carb i the voltage will also rise.

Where should i look / test next?
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Old 01-29-2017, 05:13:14 PM
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Default Re: Onan 7.5JB - Wiring

So, your saying when you first start it (Cold) you have the the 120/240 volts until it warms up.
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Old 01-29-2017, 07:13:37 PM
kiteoregon kiteoregon is offline
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Default Re: Onan 7.5JB - Wiring

I never get a voltage higher then 2.30 volts (cold or warm) unless i twist the idle screw then i can see a small rise in voltage.
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Old 01-29-2017, 07:14:14 PM
Max Thompson Max Thompson is offline
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Default Re: Onan 7.5JB - Wiring

Quote:
Originally Posted by kiteoregon View Post
i only get 2.30 volts once warmed up. If i twist the idle screw on the carb i the voltage will also rise.
"2.30" volts or 230 volts?

Use the governor adjustment screw to raise RPMs and voltage, not the idle stop screw.
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Old 01-29-2017, 07:36:48 PM
kiteoregon kiteoregon is offline
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Default Re: Onan 7.5JB - Wiring

Thats a good point, i don't know if my MM is putting a decimal in there. I will check a known 110 to verify. Which is the governor adjustment screw?
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