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Mr.RC-Cam

JR Quattro Tx hack.

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Ok, warm up those soldering irons! We're going to convert a lowly four channel JR Quattro R/C Tx to a full six channels. When complete, the radio will have a new switch activated gear channel and a fully proportional aux channel. The new channels are perfect for controlling a camera shutter and pan servo.

The mod involves adding a toggle switch, miniature pot, 2 caps, and a resistor. The Tx's circuit board involves SMT (surface mount technology) construction, so this is NOT a project for the average bear. You will probably destroy your Tx if you do not have prior SMT rework experience (this is not the project to practice on!). If you know what you are doing then this mod will take less than an hour.

Here is the new Ch-5 switch and Ch-6 knob.

post-6-1063041541_thumb.jpg

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The first thing to do is to add a .1uF 0805 SMT cap at location C26, per the photo below.

You might notice that two other new caps were installed (outlined in yellow) at C27 and C28. But, these are NOT required. So you can omit them.

post-6-1063041621_thumb.jpg

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Next, you must remove a resistor, move a resistor, and add a new cap and resistor. Please refer to the photo below.

  • Remove the 0-ohm resistor at location R22. It is not used.
  • Move the 0-ohm resistor from location R8 to location R7.
  • Add a 1K 0805 SMT resistor at location R23.
  • Add a .1uF 0805 SMT cap at location C40.

post-6-1063041709_thumb.jpg

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Next you must mount the SPST switch and a 5K to 10K pot. My parts came from my "junk" drawer so I do not have any part numbers. Both fit like a glove, so I was lucky.

By the way, they both mount in existing Tx case holes. The switch's hole is covered by a push-out plug (just pops out without a fuss). The pot will require that you cut a hole in the decorative decal on the face of the Tx (but the actual Tx case is ready to go).

post-6-1063041772_thumb.jpg

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The CH-5 gear switch (SPST type) is wired to pcb location "CN5." The CH-6 Aux pot (5K to 10K) is wired to location "CN6."

The three pot wires are connected to the pot's three terminals in the same order as found on the PCB (outside to outside, center to center).

If you want CH-5 and CH-6 servo reversing, then add SPDT slide switches to the pcb locations marked "S5" and "S6." I did not need them so they were not installed in my Tx.

post-6-1063041853_thumb.jpg

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That's all it takes. Enjoy!

If you have questions about this hack please do NOT email or PM me. Instead, post your questions or comments directly to this thread.

Regards,

Mr. RC-CAM

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That looks great !

Shh, don't tell those people that gets upset when you tell them you changed frequency on your transmitter by replacing the crystal.

Best Regards,

Bosse

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That's all it takes. Enjoy!

If you have questions about this hack please do NOT email or PM me. Instead, post your questions or comments directly to this thread.

Regards,

Mr. RC-CAM

Mr. RC-CAM

Can this same hack be done to a JR F400 tx. That's the tx that I own and when I opened it up it does not look like the Quattro. Please advise.

thanks,

davec

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The JR 400 used the old NE5044 encoder IC. There are two spare inputs on it (pins 6 & 7) that you can use for additional channels (these pins are currently grounded). Although I cannot give specific instructions for the hack, this link should help with the basics to reviving the unused channels: http://www.rcgroups.com/forums/showthread....&threadid=55575

Data sheet for the NE5044 IC: http://www.ortodoxism.ro/datasheets/philips/NE5044.pdf

JR 400 Tx schematic is attached.

JR400sch.pdf

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Thank you for this hack! I just noticed the missing 5 & 6 reversing switches on my old quattro and went looking to see if getting those channels working was difficult. I'll be frying my tx board in short order.

Is there a reason why you cannot ad a proportional control to ch5? I'm just curious at this point but it may be nice to have the option. I'm also going to look into adding trim controls to these channels for fine tuning.

Sorry if resurrecting an old thread is frowned upon here, I just had to thank you for the hack.

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Is there a reason why you cannot ad a proportional control to ch5?

My memory is a little fuzzy on this old hack, but I recall that it's not a proportional channel (on the Quattro).

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