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JB High Battery Voltage


Model: 706JB-1R/1R Serial: 0168A09152 Working on a early model JB. This set is before the...

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Old 11-11-2009, 08:25 PM
Tim0477 Tim0477 is offline
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Default JB High Battery Voltage

Model: 706JB-1R/1R
Serial: 0168A09152

Working on a early model JB. This set is before the magnicitors or electronically regulated ones. Problem is the battery voltage goes up to about 16 to 16.5 volts and boils the battery. Tried moving the sliding tap on one of the large resistors on the side. Only thing this appeared to do is to make it take longer to reach the 16 volts. Disconnected this resistor altogether and the voltage at the battery still went high although the charge current shown on the ammeter was near zero. This has a Prestolite TCA 4004 voltage regulator. Is there any way to check it for proper operation? What else can I try?

Does anybody have the proper wiring diagram for this. I have been using a remote type CCK wiring diagram that is very close. Differences between this and the CCK are this has a diode instead of a reverse current relay, there is a start disconnect relay (I think that is what it is) fed by a wire "A1" coming from the genend, and the CCK voltage regulator shows 2 connections while this one has 3.

Thanks,
Tim
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Old 11-14-2009, 12:32 PM
Leon N. Leon N. is online now
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Default Re: JB High Battery Voltage

Hello Tim:

I am very familiar with the Onan 705JB plant. I have installed and using a 705JB-3R/4703P unit since 1972. After reading your information, for openers a couple of things jump out at me. To the best of my knowledge, there is no 705JB-1R or at least I do not see any reference to such a description in my Onan literature. Please recheck the name plate.

Obviously, a 12 volt battery shoud never be charged at 16 volts. I designed a trickle charger, independant of the gen plant, which is set at 15 volts or 1.25 volts per cell. There is no Prestolite TCA 4004 voltage regulator that I am aware of. The Onan wiring diagram for the 705JB indicates a 2 ohm adjustable resistor grounded on one side and the hot side connected to B1 on the generator "charging winding". B2 from the charging winding is connected to terminal 7 control box terminal block which in turn is connected to a 1/2 wave rectifier and through the charge ammeter to the 12 volt battery.

Hope this helps. Good Luck.

Leon
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Old 11-14-2009, 02:24 PM
BGunn BGunn is offline
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Default Re: JB High Battery Voltage

I have a service sheet for the TC series voltage regulators if you feel confident in testing and adjusting.
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Old 11-14-2009, 07:41 PM
Tim0477 Tim0477 is offline
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Default Re: JB High Battery Voltage

Hi Leon,

Unit is in fact a Model: 706JB-1R/1R. Its 120 volt output only. Your unit must be different than mine. I only have a 4 position terminal block and there are no B1 and B2 wires in there. I also have 2 resistors. One is fixed the other has the sliding tap. The Prestolite Regulator removes the resistor with the sliding tap from the circuit once the battery voltage reaches around 13 volts. I finally got it working. Even though the regulator appeared to be securely bolted down, it was not getting a good ground connection. Put star washers on the bolt and now it works. I can watch the ammeter show about 5 amps after starting and then drop down to almost 0 amps when the battery voltage reaches around 13 volts. Even though the charging amps drop to near 0, the battery voltage still will eventually reach 16 volts. Thats why I am interested in the proper wiring diagram. The one resistor that remains in circuit looks like it was recently changed and I am thinking it may be the wrong value.

BGunn,
I would like to have a copy of the TC regulator service sheet. Send to t_banas at hotmail dot com.

Thanks,
Tim
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Old 11-14-2009, 08:20 PM
BGunn BGunn is offline
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Default Re: JB High Battery Voltage

I sent them, Bill.
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Old 11-15-2009, 05:20 PM
Leon N. Leon N. is online now
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Default Re: JB High Battery Voltage

Hello Tim:

My apologies. I should have looked closer at my data. Yes, your 706JB 1R is valid description. My Onan literature shows this as a revolving armature generator, not a revolving field generator. So what I told you does not apply. However, in reviewing the Onan PLs and wiring diagram, one of the following wiring diagrams applies, 611C797 (with Low Oil Pressure Circuit) Begin Spec P or 611C790 (No Low Oil Pressure Circuit) Begin Spec P. This diagram is a schmatic of the Engine & Generator Control circuitry.

What you described checks with these diagrams. However, the Relay, Charge Regulator is listed as OPnan part No. 305B383. I see no other manufacturer's reference.

Hope this helps.

Leon
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Old 11-19-2009, 08:31 PM
Tim0477 Tim0477 is offline
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Default Re: JB High Battery Voltage

Hi Leon,
You wouldn't happen to have either of those diagrams in PDF that you could email to me would you?

Bill,
Could you try re-sending the info on the Prestolite regulators? I never got it for some reason. t_banas@hotmail.com

Thanks,
Tim
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Old 11-20-2009, 05:21 PM
Leon N. Leon N. is online now
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Default Re: JB High Battery Voltage

Hi Tim:

Yes! I will send you four schematics in PDF. The two you are interested in are 611C797 or 611C790. Disregard the other two. I will send them to you at t_banas@hotmail.com today.

Leon
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