Telemetery now working- just cant get the voltage to work

JASON128 · Post by **JASON128** » Fri Mar 01, 2013 5:17 am

What have i done wrong?

I have been thought the process if connecting up my frsky module for telemetry, and on firing everything up, the screen is now blank. Radio beeps, tx module gets power, but no nothing shows on the screen.
I suspect I have fried something, although no tell-tale smells or smoke….

I had already flashed the radio for the telemetry firmware, and everything, including sthe screen was working fine.

Does anyone have any thought on what I’ve done wrong .. even if its only knowing for the next radio

So what I think I have done is this:

-Frysky module jumped to the spare two pins with a 2.7K resistor in line

-Sparkfun 232 board connected to the smartie parts board.

-Feed out to the two spare pins on the back board of the radio. These appear to be completely isolated from everything else when tested with a meter, so I have just connected them directly on.

The standard removal of the 2x 200 ohm resistors and adding jumper wires. Note I did not replace the 200 ohm resistors in line, but my understanding is these resistors are only required if the unit is flashed with the power on (which I have not done)

thomas9x · Post by **thomas9x** » Fri Mar 01, 2013 5:28 am

I have been thought the process if connecting up my frsky module for telemetry, and on firing everything up, the screen is now blank. Radio beeps, tx module gets power, but no nothing shows on the screen.
I suspect I have fried something, although no tell-tale smells or smoke….

Relax, take a deep breath, everything will be fine.

I'll bet that you disconnected the LCD ribbon cable from the main board. Because I can see the cable's left side lock is still unlatched. I recommend you unlock both sides, slide the ribbon cable out, visually inspect the contacts with a 5X lens to ensure they are undamaged & virgin clean, then re-seat the ribbon and LOCK both latches. That should fix it.

Note I did not replace the 200 ohm resistors in line, but my understanding is these resistors are only required if the unit is flashed with the power on (which I have not done)

I recommend you install those missing series resistors on your two new wires.

- Thomas

Post by **jhsa** » Fri Mar 01, 2013 5:54 am

Also make sure that those pins are really free. Normally one must cut tracks on both sides of the board..

JASON128 · Post by **JASON128** » Fri Mar 01, 2013 6:17 am

Thanks Thomas,
I have just been down in the shed and double checked- I'm pretty sure the latch/ribbon is not the problem- its just loose in the photos as i had had it apart thinking that was the problem. Even with it seated perfectly it still does not work, and there is no damage to the ribbon itself.

I have run a meter over all my wiring and there no shorts/ all looks fine.

really dissapointed pointed of I've ruined it, as it's been a very reliable radio for the last two years.

Post by **jhsa** » Fri Mar 01, 2013 6:23 am

well it's time to start trying to find the problem..

First, you said that it beeps?? does it control the servos?
Time to undo the modes you have done..

As far as I know, most people that had problems with the radio not working managed to fix it.

You are using a level converter, right? where did you power it from? also make sure that you didn't connect it the other way round. RS232 side of it goes to the frsky module, and the TTL side goes to the 9x. Also a 470 ohm resistor from the level converter to pin 2 (I think) of the processor is necessary.

This should get you started. If you're lucky the problem is one of these things and can be easily fixed.

João

JASON128 · Post by **JASON128** » Fri Mar 01, 2013 7:43 am

Thank you both for the fast & detailed replies.
I decided the best approach was was to undo what I have done and see if I can get the screen live again.
This was easy- just remove the smartie parts board and unsolder the yellow green wires i have going to the spare Frsky module pins on the back board.

Even with the 232 converter completely removed, things are still not looking good.
although the Tx module is getting power, it does not appear to transmit anymore- i cant get any recievers to respond to it.

sot he transmitter is not completely back to the origional factory design, The only part I have not removed is the 2 fine wires off the main chip and missing resistors but i cant see how these can relate to the screen. looking at it all i wonder if i have overheated the chip when soldering the two wires onto it?

Post by **jhsa** » Fri Mar 01, 2013 10:11 am

unsolder the 2 wires from the side where the resistors were. you will have to put resistors on them anyway..
Also check if the 2 pins at the top are not shorted..
If all this fails you will have to measure voltages on the regulators, carefully not to shor anything.

Flaps 30 · Post by **Flaps 30** » Fri Mar 01, 2013 2:31 pm

JASON128 wrote:What have i done wrong?

The standard removal of the 2x 200 ohm resistors and adding jumper wires. Note I did not replace the 200 ohm resistors in line, but my understanding is these resistors are only required if the unit is flashed with the power on (which I have not done)

Looks like you haven't done this part of the modification correctly, as it does look like you have missed the vital part where you have to cut the traces/tracks at the top of the two resistors that go to the two pads which feed pins 2 & 3 on the chip. The way you have it now, looks like pins 2 & 3 connect to pins 41 & 42 of the chip via the two 200 Ohm chip resistors which is wrong.

Post by **MikeB** » Fri Mar 01, 2013 2:37 pm

Looks to me that you have wired to pins 40 and 41, not 41 and 42. Pin 40 is one of the LCD control signals.

Mike.

Post by **jhsa** » Fri Mar 01, 2013 2:42 pm

Mike you are absolutely right.. good catch..

Flaps 30 · Post by **Flaps 30** » Fri Mar 01, 2013 2:58 pm

Ohh yes... Good one Mike.. I was so busy looking at other things that the obvious got missed.

Scratch what I said earlier. I have noticed that the two resistors in question have been removed. Poor angle on my nasty LED monitor (I love CRT's) darkened that area so much that I couldn't see clearly.

JASON128 · Post by **JASON128** » Fri Mar 01, 2013 9:49 pm

Awsome!
thanks so much guys- looking at it I cant believe i messed that, I must have checked it all a dozen times!
will unsolder and report back as soon as I have a chance.

in the meantime I now have a 9xr on its way too..... I couldn't risk being stuck with nothing for too long, as this is my only tx. Ill be curious to see how it compared to the 9x

JASON128 · Post by **JASON128** » Mon Mar 04, 2013 7:01 am

yep the mis-allocated pins were the problem. i Just cut the wires to test.
will resolder it all and get it going soon

thanks so much for the words of wisdom

Cheers

Post by **jhsa** » Mon Mar 04, 2013 11:59 am

Don't forget to solder two 200 or 220 ohm resistors on those wires.. they are necessary..

João

JASON128 · Post by **JASON128** » Sat Apr 20, 2013 11:35 pm

I finally found time to re do the mistakes I had made- and its all almost working- fantastic.

Thanks for all the help to this point- I would have not have it working without the help of this forum.
So the TX/ RX levels not show up- which i assume means everythign must be working perfectly hardware wise. However i cannot get a voltage output off the D8R-XP or D8R-SP receivers i have.

I have tried rebinding them etc, and made sure the jumoer between A1 & X is in place.

the TELEMETERY 10/12 pages shows:

UsrProto FR Hub Met
A1 Channel 0.0v 0.00

am i missing something , or i still have something wrong in the hardware side of things?

Post by **Kilrah** » Sun Apr 21, 2013 6:01 am

You need to set the "0.0v" to the full scale span of the sensor (3.3V * 4 = 13.2)

JASON128 · Post by **JASON128** » Mon Apr 22, 2013 6:09 am

Fantastic thanks- i had tried to adjust this but didnt seem to be able to- after trying a few more times- perfect!
thanks so much for your help

All fully telemetry functioning now- so very cool

Post by **jhsa** » Mon Apr 22, 2013 1:41 pm

Great.. well done..

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