Jensen Radio only works on house power

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JoelP

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My Jensen VR209 radio fails to power on when switched to chassis power, but works fine on the house power switch position. I noticed this recently and was puzzled by the fact that the radio LEDs all light up, but the radio doesn't function on chassis power.  While I was changing out my CRT backup monitor today I looked for a loose connector or wire and spotted a blue wire that was seemingly broken off from wherever it was previously attached.  Now I am trying to figure out where that might me.  I looked at the connector info and the online Winnebago info for my rig and still am having difficulty figuring this out.  A blue wire should correspond to 12V 100mA out rather than power in.  I would have thought the missing wire should be a red wire.  Any thoughts on this?
 

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Gary RV_Wizard

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Modern vehicle radios often have two power connections, one for stand-by mode that keeps the dial lit and the clock on, and a second for active audio (radio turned on). The stand-by power line is wired direct to the chassis 12v source, while the "ON" power line is connected to the ignition-on chassis 12v.  That's so the radio will go off when the key is turned off, but the panel can still display time or whatever.
 

JoelP

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Thanks for both of these answers.  I think the issue is more related to the connections to the radio than the radio itself.

John Canfield said:
Download your user manual for that radio. The blue wire might be to power an automatic antenna or external amp.


The radio manual and the table on the radio call out that there is a blue wire for a power antenna, but there is no such power antenna.  Besides, if this were the missing blue wire the radio would not work on the house position of the switch.  I think I need to look more closely at where that switch is connected.  Perhaps this fell off of that switch.  It is a bit more difficult to see the back of that switch.


Gary RV_Wizard said:
Modern vehicle radios often have two power connections, one for stand-by mode that keeps the dial lit and the clock on, and a second for active audio (radio turned on). The stand-by power line is wired direct to the chassis 12v source, while the "ON" power line is connected to the ignition-on chassis 12v.  That's so the radio will go off when the key is turned off, but the panel can still display time or whatever.

Yes, agree that this must be the case, but I cannot find this circuit in the Winnebago reference wiring diagram.  Perhaps I need to look some more.
 

JoelP

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John Canfield said:
Winnebago doesn't do much documenting of vendor supplied electronics other than interface wiring.


When I study the diagrams they show the radio switch, the grade brake switch and the overdrive switch, all of which are at the front of the chassis, but while they show the wires coming from the grade brake and overdrive switch, they show nothing for the wires attached to the radio switch in the front of chassis diagram.
 

Gary RV_Wizard

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I would guess that only the Main "ON" power wire is switched between house and chassis systems. The auxiliary (stand-by) power is probably always on the chassis battery. The chassis ground is the same regardless of the power source.
 

ChasA

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Joel, are you running the engine?  I'm pretty sure it has to be running to work from the chassis setting.
 

John Canfield

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I have a rocker switch for my dash radio power - chassis is one position and house is the other. Doesn't require the engine to be running or ignition switch to the on position.
 

cbeierl

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John Canfield said:
I have a rocker switch for my dash radio power - chassis is one position and house is the other. Doesn't require the engine to be running or ignition switch to the on position.
You sure about that John?  When my dash radio is switched to 'chassis/engine' it only operates with the ignition on (or at least accessory).
OnEdit: Typo Fix
 
O

Oscar Mike

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So far my in dash system only works on chassis power, between us we're good to go...
 

JoelP

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Today I had a look at the back of that switch and found no loose or missing wires.  While I was there I was surprised to see that a +12V and ground wire was connected to each of two connectors on each side of the radio with a opening facing downward toward the floor,  I never noticed these before until I went looking at this radio switch. I have to wonder the purpose of these.

I am sure that the radio switch worked before, but now this only works on house power. I am beginning to suspect the switch itself and will check that next.
 

John Canfield

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cbeierl said:
You sure about that John?  When my dash radio is switched to 'chassis/engine' it only operates with the ignition on (or at least accessory).
OnEdit: Typo Fix
Hmmm. I thought so but I'll have to check - you might be correct.
 

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