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help conecting the 4PDT relay

1701 Views 5 Replies 3 Participants Last post by  Mocking-DX
hi everybody

i just got my avc rgb1 from ron. Modifying the unit is not that hard. Connecting the relay i bought from radioshack is what's confusing me. I don't wanna miswire it and blew my navigation.


Which of the 3 rows of 4-pins goes to which--monitor/navi computer/RGB1 unit. I think it's the set of 4 next to the 2-pin

what are the 2 extra pins aside from the 3 rows of 4-pins. I assume it's where you connect the power. Does 1 pin connect to a power source and the other 1 to a ground?

and how do you control the relay so you can choose which one you wanna see on the monitor, e.i. navi or video source(RGB1 unit)

I'm hoping to finish my project this weekend so pls somebody help. Thanks in advance
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I think i figured it out:

Ok the 4PDT relay has 4 rows of pins.
The first three rows have 4 pins each.The 4th row of pins has only 2.

You can see that the 3rd row is slightly farther from the first two rows
| o o o o | ---connect to navigation computer
| o o o o | ---connect to AVC RGB1
| |
| o o o o | ---connect to the navi monitor
| |
| o o | ---connect to a switch then to power source, ground
|_______| the other pin

the first row(top) of 4 pins in the 4PDT relay are connected to the navi computer because this is the circuit that is always on when there's no power/current being applied to the relay, meaning the relay switch is turned off.

the second row of 4 pins is connected to the AVC-RGB1.That's because this circuit is not connected to the monitor when the 4PDT relay is switched to off.

If you turn on the switch that powers the relay, the image on the screen will switch from navi comp to RGB1 video source. That's because an electromagnet in the relay is activated when the power on the relay is swithed on. This will then pull the 4 metal contact switches(inside the relay) and disconnects signal from the navi computer . These metal contacts will then connect to the video signal (3rd row of 4 pins) coming from the RGB1. In turn the monitor will display the video from the RGB1.

Whew! Actually I just figured this out by staring at the 4PDT relay and look what's inside and found out there's 4 set of metal strips in between the 1st and 2nd rows of 4 pins. And there's an electromagnet that looks like a spool of thread. There are 2 electromagnet's wires that are connected to the 4th row with 2 pins--which means connections to power source to activate the electromagnet.

anybody is welcome to pls correct me if my analysis of the relay is wrong before it's too late for me. Thanks. I'm doing this tomorrow.
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That looks and sounds correct. There is a schematic on the back of the Radio Shack Relay package that show how the sucker works. Your verbal description is correct, only item to note is I like to place a 1N4001 diode across the relay coil with silver band to the + side.

Hi Steve,

Thanks a lot for confirming my interpretation of the relay. Actually i already hooked up our Handycam to test the mod. I crossed my fingers and luckily I was able to view our last September's caribbean cruise on my newly modded navi screen. IT WORKS!!! I just took the chance. I'm finalizing the set up tomorrow, plus i'm hooking up an FM modulator.

Couple of questions to Video Navi
--You(or extreme or Digital MDXs??) mentioned before in a post that you(they) prefer the Relay because you can control the fm modulator also. Do you mean I can hook the modulator power wire parallel with the relay? So the modulator will only turn on when I turn on the relay, which is good coz the FM modulator needs to be turned off if I want to listen to FM. Hmmm. Pls confirm.

--Is it OK to get the power source for the Relay (together with the FM Modulator) from the Blue accesory wire from the RGB1? Or do you suggest getting the relay power from the radio or monitor in order not to put too much load on the navigation accesory wire. If you recommend the radio/monitor, would you pls tell me which wire to tap?

--where's a good spot to put the relay switch?

--AND what does a 1N4001 diode do?

Thanks a lot to you and everybody else who contributed their ideas unselfishly to this type of project.
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I've posted a copy of the relay diagram below.
The diode is an added safety measure. Diodes allow current flow in one direction only. The are very low resistance in one direction and high resistance in the other direction.
Location of the switch is up to you. You can go for a dash mount or under dash, center console, under seat, etc. It all depends on convenience and how visible you want it, I don't want my dealer messing around with my setup but then again I don't want to crawl under the car to switch video inputs.
Congrats on getting the mod going... keep us posted.


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Thanks digital MDX

PS2 works fine so far, as long as i secure it vertically in the 3rd row seat. It skips if mounted horizontlly. I'm still trying to think where i can vertically mount it, somewhere easily accesible. my omnly gripe is the sound. I have to really crank the volume up so I can hear the voice in the movie. That's because i'm using a 4 ohm speakers with my stock speaker. I'd either replace my amp to 4 ohms or find some 5.1/DTS decoder to hooke up to the ps2 AND radio IF POSSIBLE AT ALL:(
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