What is behind this black board?

[kaos]

I am going to mod my Sky9x installed T9X to run telemetry tx/rx through the original antenna wire hole to the module cavity and wire 2 spring loaded pins and contact on the back of the module cavity (from the Sky9x board) and the Frysky module (inside module the Tx/rx pin will extended to this area with contact/spring loaded pins). This way the module is completely removable without connecting telemetry wires. (done by the 2 spring loaded pins, while still be able to swap to other module).
But to do that I need to cut that antenna hole on the back board the Tx to accommodate 2 spring loaded pin/contact.
My question is what is in that area of the board that is covered by the black coating? Any circuitry I need to avoid in that little square area?
here is the area looking through the module cavity of the Tx:

[Clivew]

If I understand correctly, you intend to connect the 2.4ghz antenna through spring loaded pins??
If that is what you intend to do I would suggest you didn't

Sorry, just re-read your post, me being stupid!
As I remember most of that black bit is just groundplane, with a few tracks
running vertically on the side where the pins are, maybe 15mm or so??
I would sand the black off carefully and have a look to be sure.

Clive

[jhsa]

it's like having a look at the dark side of the moon.. we know there's something there but we don't know what

[kaos]

NO, not the antenna. the telemetry tx/rx wires from DJT to SKY9X telemetry header.

The DARK LORD always wins.

[jhsa]

yeah, may the force be with you.. to do that mod...

[Rob Thomson]

I have drilled through that area before. Just a big ground pad!

[Kilrah]

Why not use the 2 free pins?

Sent via SGS3

[ShowMaster]

Is it possible it's left over as part of the original antenna counterpoise system or a rf shield to keep any leakage radiated from the module from getting into the radio?
I know the case is plastic and the main CPU board is lower on the case so maybe it's a old counterpoise and not a shied.



ShowMaster
Sent from my iPod touch using Tapatalk

[kaos]

Thx Jhsa and Rob. I will just drill then. But now Kilrah brought up those 'two free pins' thingy.
I sort of vaguely remember the two free pins, but can't remember where it is now.
Kilrah, refresh me about those 2 free pins.
keep in mind, this mod is to have the DJT telemetry module completely removable with one plug in and the Txd/Rxd is connected at the same time without plugging in additional wire. while still can use other module with/without telemetry.

[Rob Thomson]

Check the telemetry mod docs on the wiki. The one Mike did is the one with the guide you want

[jhsa]

There are also some good pictures of the cuts that have to be done on the traces on both sides of the board in order to free the two pins.. one of them (pin 2 I think) is grounded on both sides of that board and must be disconnected from it.. one of these traces is under the black material, so care must be taken that the pin is really isolated from ground as that could damage your frsky module..
The problem is that I can't find the link on the wiki.. It was written by someone that did the mods and did a very guide as well with lots of pictures.

Joao

EDIT: Found it.. This is very well documented..

http://openrcforums.com/wiki/index.php/ ... _Telemetry

[Kilrah]

Or this: viewtopic.php?f=23&t=430

Being able to swap modules cleanly was obviously the goal.

[Crucial]

http://openrcforums.com/wiki/index.php/ ... on_your_9x

I had never seen this before. It is a buried gem in the wiki.

[SkyNorth]

One thing to consider , doing any mods to the RF module , voids all CE and FCC certifications.
If that maters to you...

-Brent

[Rob Thomson]

So really..., frsky need to sell their modules with the rf mod done!

[kaos]

thx, now I remember that mod. Read that while still on the stock board. I was going to do it but stopped short because of the cpu legs soldering techical issue. Then the SKY9x board came out. so that faded.

Ok, if I go for the 'level converter' route, do i need do mode the original Flysky module as listed in Crucial's link?
and I should be able to just connect the 2 wires from the back board straight to the txd/rxd header on the SKY9x board?

Kilrah: why you have 2 DJT modules in the pic? any different function between them?

[kaos]

One thing to consider , doing any mods to the RF module , voids all CE and FCC certifications.
If that maters to you...

-Brent

I may be wrong, I sort of remember reading the module mod actually means the module board (like the DSMX module board, like the DX6i module pulled from the DX4e, not the other part inside the module or tx box. I may be wrong. Some where in my brain I had that impression.

[mbanzi]

http://openrcforums.com/wiki/index.php/ ... on_your_9x

I had never seen this before. It is a buried gem in the wiki.

Why thank you! I created the Wiki to have single source of information after having to dig around a lot to find info on all the different mods.

[kaos]

yep, I read all those mods prior the SKY9x board. but not sure how those exactly applied to the Sky9x board. I am not going to 2nd guess of electronic circuitry.

[SkyNorth]

All your doing is moving the external rs232 connections to the 2 unused pins on the plugin port for the Module.
Not that anyone would know you have done it ..BUT ....
There are some anal people out there that might not let you fly at "their " fields if they see the hacking done to the RF module

I dont see anything wrong with it , but when things are changed without approval , then there are No approvals anymore .... This is how UL and CSA and VDE stay in business....

The black board and the 2 fingers are the Ground Plane for the old 72mhz antenna system , The 2.4Mhz modules should have there own
built-in ground planes

-Brent

[Kilrah]

Ok, if I go for the 'level converter' route, do i need do mode the original Flysky module as listed in Crucial's link?

Ah, sky9x board. Forgot that.

The sky9x board has an integrated level converter. So no need to put one, and no need to scratch tracks like I did in my mod. Just use Mike's guide for what needs to be done in the module:

Then yep, directly connect the 2 pins from the backplane to the header on the sky9x board.

Kilrah: why you have 2 DJT modules in the pic? any different function between them?

As it's my main system I got one for each radio, everything modded identically

I've actually given that 2nd radio away to a friend with the module sometime ago, and then re-modded a set last week, including the atmega128 mod this time

[kaos]

OK, back here again. I was stuck with the placement of wheel encoder for a day. but now it is all OK.

Kilrah, that is a BIG 'forgot'.

yes, before I start I definitely want to make sure every thing works as intended.
Yes, again this is for a Sky9x board.

OK, once I do the Mike's mod in DJT (which is simpler too ) , I will cut tract on the back board of the TX according to Mike's guide pin2 cut both side of the board to free pin2 and only cut the solder side on pin 5.

After I have done this. Ok, my DJT is simple to be removable for the SKY9x board. now If I put this module back to a Tx with stock board (no telemetry mod) can I use the module (of course no telemetry either) which does not have the track cut on the back board?
and once I cut the traces on the back board , should I still be able to use stock module and my DSMX module? or I have to cut tracks on the push button board for those two module like in Mbazi's guide in wiki?
These are the areas I am confused/not sure.
Doing mod on one Tx is not too bad. but to work with all 3 Tx and 3 modules is where I am not sure.

I am thinking which way is easier. If I add two spring loaded pins in the tx with SKY9x board and 2 contacts in the DJT module (as implied with this thread title), this module can be put in any Tx I have like it is now. no change unless there are two spring loaded pins in the tx with a sky9x board.

I have one T9x with stock board/FW, one T9x with SP board, no mod/er9x, one T9x with Sky9x board/ersky9x.
I think I will upgrade the 2nd one to Sky9X v3 and use that tx with open9x.
then the sp board will go back to my old trusty Turnigy Tx.
But any mod I make, needs to be compatible with all 3 Tx.

Did i confuse you?

[MikeB]

I think a modified DJT module is OK to put into an unmodified stock system. The RXD signal has a resistor in line which will protect it, the TXD signal goes, I believe, only to the connection to the old FM aerial.

The problem with the stock Tx module is pin 2 is connected to ground. This will short the transmit data from the TX level shifter to ground, not good, if you plug it into a tk with the telemetry mod. If you added a 4K7 resistor in the lead from the TXD of the level converter leading to the pin this connects to, you should be OK, otherwise you need to cut the tracks in the stock module on pin 2.

I have no idea regarding the DSMK module.

Mike.

[kaos]

hmm, looks like from all I read here. the simplest way for my situation would be adding two spring loaded pins to get the Txd/Rxd from DJT. with 2 Tx will be loaded with Sky9x that take care of the problem of easy plug in and still both tx still can use stock module / DSMX module.
The one still has the stock board, when modded with telemetry I just use the same spring loaded pins and do the conversion in the Tx for Txd/Rxd from DJT.

Hmm, I think I never really think about this only been fooling around with DJT with sky9x so far: I can plug a stock module and DSMX module to the SKy9x equipped Tx, right?

This will work?

found these:
for contact on the back of DJT module:
http://www.mouser.com/Search/ProductDet ... 0150000030

for spring loaded pins for the tx placed in the 'black are':
http://www.mouser.com/Search/ProductDet ... 5208214110

[Clivew]

Hey, where did you get a DSMX module from?
Just checked my DM9 DSM2 module, there is no problem there.
The pin in question isn't connected to anything.
I seem to remember this pin was used for 9 volts supply
on JR transmitters when using a 35mhz module for the pa stage
Of course, if you made your own DSMX module. you wouldn't
use that pin anyway

Clive

[kaos]

Pulled from a DX4E , THe how to is in wiki now.

[Kilrah]

I think a modified DJT module is OK to put into an unmodified stock system. The RXD signal has a resistor in line which will protect it, the TXD signal goes, I believe, only to the connection to the old FM aerial.

The problem with the stock Tx module is pin 2 is connected to ground. This will short the transmit data from the TX level shifter to ground, not good, if you plug it into a tk with the telemetry mod. If you added a 4K7 resistor in the lead from the TXD of the level converter leading to the pin this connects to, you should be OK, otherwise you need to cut the tracks in the stock module on pin 2.

What I've done is protect the 2 TXD's. RXD's as inputs won't mind being pulled to ground, but I've put a resistor inline with the module's TXD in the module so shorting it on the back board is no problem, and one inline with the radio's TXD in the radio, so inserting a module with grounded pin is no problem either. My only radios with JR slots are 9x's, so I didn't add Mike's res in the module on the RXD line. You might want to do it if you think you might insert your module in an old JR radio that supplies the battery voltage there.
I also isolated the 2 pins on my stock module and stock-based DSMX module for peace of mind although it wouldn't be strictly necessary with the above.

Stock - sky9x cooperation interoperability shouldn't be an issue.

[kaos]

Thank you all.

I think what I summarize from you all is: my sky9x board, I can use stock module, DJT module and the DSMX outlined by kilrah without any problem. so to me the easiest way for me would be adding the spring loaded pins for txd/rxd from DJT to the SKY9x board header. This way I don't need to change any thing for stock module or DSMX mdodule and no mod beside solder 2 single wire to Txd/rxd in DJT.

From Mike's pdf file, he mentioned there is plenty of room to solder 2 wires in DJT 's txd and rxd and still be bale to plug the FLD-02 screen (when needed) to the connector without any problem. If I go this way, before my stock Tx is modded with telemetry, I can still use DJT and attach the FLD-02 screen to get DJT telemetry.

Down the road, I think I will just mod my original stock T9x for telemetry (if I ever done that, since I will have 2 T9X with Sky9X board by that time) and use the same layout of the spring loaded txd/rxd pins and connect the rs232 converter to those 2 wires. This way one module of each kind can be swapped among all 3 Tx without any problem. (all 3 Tx will have the spring loaded pins in the 'black hole' for DJT's txd/rxd).

I like to do things the 'easy' way, which may not be the 'cleaniest way'.

Kilrah: can you confirm what I layed out will work? Thx.

[kaos]

OK, got the pins and contacts for routing txd/rxd to the back of Tx. opened up the DJT module. what is hold the pcb in the module? Is it glued to the back of the module box? Just can't get it out of the box. anyone taken out this board before know what is going on between the pcb and the box? Is mine just wedged perfectly in the module box?

[Kilrah]

Not glued, just "pinched" between the side walls. Pull on the little board with the DIP switches while twisting the case a bit.