Project: Install ProDVR inside TBS Tango


#1

Okay, I need some help, and I’m casting the net far and wide…

I want to do this mod:

I have the TBS Tango, and an Eachine ProDVR. I’ve got this “how to” for a mod with the Eachine Goggles Two:

I’ve got the pinout of the ProDVR:

I’ve got pics of the Tango boards:

Power Board

Main Board (back facing)

Main Board (front facing)

Display Control Board

There is an existing option with the RJ45 port on the Tango, but I was really hoping to install the DVR inside the unit:
image

I’ll need to handle the switches as well, but I’m mostly interested in splicing the video signal properly.

The only thing I can think of to start is to use trial-and-error to figure out the 9=pin connector between the “Main Board (front facing)” and the “Display Control Board”; from the left, pins 2, 8, and 9 are NOT used:
image

Any other ideas?


#2

Try to find the video signal on the small white JST SH (?) connector next to the VRX or maybe solder to the VRX directly (maybe a bit ugly). Crimping your own cable harness for that connector would probably the least invasive and cleanest way, assuming that connector has the video signal from the VRX.


#3

Thanks, yeah, was wondering the safest way to do that, but then you made me realize it’s pretty much as simple as that… getting the video signal; that’s the only invasive part to this mod, right?

So, I took off the bottom board, what I called the Power Board, and it has the RJ45 connector made for external output (to goggles, and/or…). Flipping it over, I’ve got a clear shot at the pins to that connector, and if I’m reading the diagrams properly, I should be able to get the video signal from the third pin (and fourth for ground) from the right here (they’d be numbered right-to-left, lining up with the pinout of the connector in the second-from-last diagram in the OP):

I’m going to test that, and maybe grab power from those pins as well (pins 1 and 2).


#4

Just realized that won’t work like I want since it won’t be inline with the screen itself. Gotta poke those pins in the connector like you suggested, @las.


#5

Finally worked up the nerve to try the next step of analysis, to measure each of the wires in the 9-pin connector between the Main Board and the LCD Display. Here’s what I was working on:

…and here’s what I measured:

image

I determined the “Affects POWER” and “Affects VIDEO” columns by pulling each wire from the connector, one at a time, and watching the effect on the LCD Display.

Current Challenge

I don’t know how to ensure which pins are GROUND, and I don’t know what pins 3 through 6 would do. Any suggestions on how to do that?


#6

GND pins are going to have continuity with the antenna GND as well as that metal shield over the tx module. Looks like you’ve identified the video correctly though.


#7

Thanks @Chaotix, confirmed continuity of ground for pins 3 and 6.

So what would you presume the 3.3V lines are?

Updated Pinout

image


#8

My guess is 3.3V are running any on board chips, that’s really common voltage for boards to run at.


#9

So, on the lower bank of wires (labelled “1”), how do I use the wires to control the DVR functions? Is it just crossing closing the circuit between any of the top three, with ground? And then is it when I disconnect the circuit that it fires, or when I first close it; like pressing down or letting up on a button? How can I know that?

I have two rheostats available, that move left and right with tension (snap back to middle when I let go). I’d like to use those for the forward and backward buttons.

Then, I have two 2-position switches, and I’m guessing I’ll use one of them for start/stop, but that might not work, since they stay in position up-or-down, as opposed to pressing a button… hmmm…


#10

My bet is that those pins are pulled HIGH inside the box, and pulling them LOW (E.G. short them to GND) signals. Whether it’s the falling edge (HIGH to LOW transition) or the rising edge (LOW to HIGH transition) I have no idea.

I don’t think the rheostat (hopefully variable resistor, rheostats only have two pins and won’t work for you) will go well for you, but you could try putting the wiper (middle pin) on GND and the two outer pins on forward/reverse. The resistance range of the variable resistor will determine whether it works.
You can get DPST(?) self-centering switches, those might be your best bet. One of them for forward/reverse and a button for Stop(/menu?)
Or three buttons of course.


#11

Required reading at this point: https://learn.sparkfun.com/tutorials/switch-basics


#12

Plan is to use an S7V7F5 Pololu for power off of vias next to the VRX (bottom of this image); thinking this will give a steady 5V for the ProDVR, and less work using the bottom vias instead of the upper pair giving 9.5V:

So, got power, got video signal…, I’m mounting the ProDVR like so:

Masked off the slot for the MicroSD, will Dremel that out, and still then just having to figure the switches.


#13

I depinned the two wires from the 9-pin connector that were for Video and Ground, but then I realized that I didn’t know if they were the same pin locations on the Video Card! Thankfully, I saw that the Video Card had the pinout silkscreened (it says GND and VIDEO under the top part of the white blob):

Here’s the Updated Pinout Table:

image

Pololu installed

Overview of Wiring

Spliced video signal, sourced from 9-pin connector, sent to V_IN on ProDVR, back out from ProDVR through V_OUT, then into VIDEO wire on Video Card. I just can’t bring myself to cut original wiring, so I spliced in a JST connector. Not sure if I’m going to wire the Video Ground signals, will see how things go as is first.


#14

Moment of truth… applied power, but first with the DVR unplugged from the Pololu, and DMM measure 5.13V. Plugged in LCD and DVR, and powered up again, and I clearly saw the ProDVR on the LCD… SUCCESS, kinda… I don’t have a way of looking at the video signal without the ProDVR, which I definitely want, since watching through the DVR will inject latency delays in the video signal.

So, new problem… how to toggle the ProDVR on or off from the LCD display.

Edit: I think I want one of these, an SP3T On-On-Mom switch. This would let me switch between Cam (On), DVR (On), or DVR Menu (Mom). Does that make sense?

Then, I can use another switch I already have that is SPDT Mom-Off-Mom, to control the DVR Playback for Forward-and-Reverse.


#15

Update on installing switches…

Switches have three “modes” – ON, OFF, and MOM, where ON will stay switched on, OFF will stay switched off, and MOM which will be on momentarily while the switch is held. MOM switches are spring loaded, and will spring away from that position when released.

Bought this ON-OFF-MOM switch for flipping between CAM_VID | DVR_VID | DVR_MENU. It didn’t come with hardware, so do pay attention if you buy a switch. Also, this was the first time I found the thread pitch to be different from my other switches, so you’d need a nut that matches. You can see the measure of the “Bushing Thread” in the specs, which will help find a match.

https://www.digikey.com/products/en?keywords=100DP7T6B11M1QE-ND

The reason I picked this switch is that it will stay ON for CAM DIRECT view to the LCD, stay in OFF for DVR DIRECT view to the LCD, and switch momentary for pressing the MENU button on the DVR. I have yet to test this, but this is my plan.

Also took an unused switch from my Taranis Q X7 for RWD | IDLE | FWD controls of the DVR. This is a MOM-OFF-MOM switch, thus it will go FWD or REV while the switch is held in that position.

When I tested continuity on the first switch, I got these measurements:

image

I’ll use this info when wiring to the DVR. Feeling excited to put it all together, but trying to do this methodically to make sure I don’t do something prematurely.

Here’s the planned switch layout:


#16

Well, finally wired things up, and did a “dry fit” test (before cinching the case back together. I get all the functionality I expect, except I can’t seem to get the “menu button” feature to work properly when I use the wiring harness. The “menu button” works when I use the actual button on the ProDVR circuit board, so the board is okay.

But when I use the harness connected to my moment switch, I expect to be able to do two things: “tap” the switch down for short press, and “hold” the switch down for long press. Unfortunately, I can only get it to respond as a long press, regardless of how quickly I tap the switch; only once was I able to get it to respond as a short press, but haven’t been able to reproduce that behavior.

I’m wondering if I need more/less resistance in the switch? @Bobnova, or anyone else, any ideas?

Besides this, I’m done, and I can complete the documentation.


#17

For documentation purposes, here are the messy shots I took before closing the case. I’m going to live with the switch problem because I’ve run out of patience.


I need a more secure mounting for the ProDVR board inside, as it moves too much when I insert/remove the MicroSD. Aside from that and the switch problem, this is done, and I’ll tidy up documentation soon.


#18

My first time out with this was a mixed bag. The mounting of the board is inadequate, as inserting a card moves the board way too much.

The switch issue is still there, but tolerable.

The more mysterious thing is that switching between DVR and CAM seems to have stopped recording prematurely. I’ll need to investigate that more fully.


#19

Hi burtlo, how is the status of your project? Did you made any improvements ont the issues? I’m very interested in doing it!


#20

I’ve only been able to find this schematic from the “Tarango” project, am hoping to review my wiring sometime soon: