DSM mod resistor and antenna questions

sberri · Post by **sberri** » Fri Jun 15, 2012 7:17 am

I have a dx4e module, 3.3v ubec, and a brand new parkeflyer Flyer9x that comes from factory flashed with Er9x r708( it's basically a flashed Turnigy 9x version 2 hardware) and will be picking up a 4k7 ohm resistor and diode tomorrow. After reading numerous posts here and on 9xforums, including the wiki, I still have a couple of questions before I attempt the DSM mod though ....

1.Does the 4k7 resistor need to be a metal film resistor or will a carbon film work as well? I know that metal film resistors have have better tolerances and are usually used in high frequency applications over carbon film alternatives.

2. The antenna situation is confusing. I do not plan on using any type of RX other than DSM/DSM2/DSMX compatible units. I will not be using telemetry either. Can I simply replace the stock antenna with the antenna from my dx4e module? In other words, is it possible to simply desolder both antennas from their respective transmitters and solder the dx4e antenna to the exact contacts the 9x's original antenna was soldered to?

Thank you in advanced for your help.

Post by **Crucial** » Fri Jun 15, 2012 3:06 pm

Have you checked out the wiki article? http://openrcforums.com/wiki/index.php/ ... tocol#DX4e

There are pics that show the dx4e antenna which is not soldered but uses a connector. You will be removing the stock module and antenna completely and mounting the dx4e antenna somewhere on the radio. The most logical place would be to put it where the old antenna was mounted.

sberri · Post by **sberri** » Fri Jun 15, 2012 3:33 pm

yes, i have read that wiki article. the removal of the dx4e module was very well documented. but, i found it rather vague in regards to what happens to the original 9x module and antenna. thank you for the answer.

do you have an opinion on whether a 4k7 metal film resistor is needed for the dx4e module, or can a 4k7 carbon film resistor be used?

Post by **Crucial** » Fri Jun 15, 2012 4:58 pm

carbon is fine.

sberri · Post by **sberri** » Fri Jun 15, 2012 5:10 pm

thank you very much

Post by **cre8tiveleo** » Fri Jun 15, 2012 5:13 pm

sberri wrote:,.i found it rather vague in regards to what happens to the original 9x module and antenna. ...?

That solution is up to you.

From the wiki...

'The final step is the antenna. You can leave the stock module in the unit and use both. Some opted to use a switch and connect the ppm and power to it, so one module works at a time. I have removed the old module and placed the DSM antenna in place of the stock radio antenna.'

Its left up to you, be creative. Its rather straight forward, remove the old one, put the new one there, or just use both, you have to mount the other antenna where you want it to be. Your choice, you had the nerve to mod your radio with the guide, now it's your time to shine and be creative.

Cheers.

mbanzi · Post by **mbanzi** » Fri Jun 15, 2012 7:23 pm

I found RCModelReviews had a pretty good explanation on how to do the antenna mod. The video is long but worth the watch, look at around 8:00 for the antenna mod:

http://www.youtube.com/watch?v=DHnV6hGH ... age#t=481s

sberri · Post by **sberri** » Fri Jun 15, 2012 11:52 pm

I'd like to thank all of you for your help. I'll be performing the mod tonight. I'll be sure to post my results....

sberri · Post by **sberri** » Sun Jun 17, 2012 1:20 pm

Okay, got mod installed but I'm experiencing a weird problem. I cannot change menu pages at all. All six buttons do nothing once transmitter has finished booting up. I can hold down any of the six buttons during boot and the each button functions normally, i.e. forces the loading of one of the existing configured models. I also can't get transmitter to bind with either of my DSM2 helis. The binding issue may be occurring because I can't get into the menu to enable the DSM protocol . Any ideas on what may be the problem?

Post by **MikeB** » Sun Jun 17, 2012 1:28 pm

Where are you trims? If a trim switch is 'seen' as held ON, it will lock out the six buttons.

Mike.

sberri · Post by **sberri** » Sun Jun 17, 2012 1:48 pm

post edited

sberri · Post by **sberri** » Sun Jun 17, 2012 1:56 pm

both trims on right stick are centered and adjustable. left stick, throttle not centered. Throttle trim is displayed at the bottom of its range and I can't change it. pressing the trim button up results in two beeps. rudder trim is centered, but pressing its trim button results in nothing happening. Nothing has been changed in programming other than a Parkeflyer installed clean flash of Er9x

Post by **MikeB** » Sun Jun 17, 2012 2:16 pm

Sounds as though the throttle trim down switch is appearing as connected to 0V. Check for shorts on the signal. The switch connects to a small, T shaped PCB just towards the centre of the radio from the stick assembly.

Mike.

sberri · Post by **sberri** » Sun Jun 17, 2012 3:51 pm

You hit the nail right on the head with your assessment. I used a can of compressed air to blow out some strange metallic "dust" from under the throttle trim switches. Thanks for your help

Post by **MikeB** » Sun Jun 17, 2012 4:01 pm

No problem, I came across the trim switches locking out the 6 buttons before.

Mike.

sberri · Post by **sberri** » Mon Jun 18, 2012 8:35 pm

Well, the lockout problem came back. The 9x is sensing 3 of the 4 left stick trim buttons as stuck in a closed state. I've verified each of the three circuits paths from their starting points at the buttons to the cpu pins that not shorts to ground exist. the three buttons themselves are fubctioning correctly as well. The 200ohm resistors in the circuits meter correct values. I'm at a loss, could a corrupt firmware flash be causing this

sberri · Post by **sberri** » Mon Jun 18, 2012 9:11 pm

Another quick note, unplugging the trim harnesses from the board eliminates the lockup problem but that obviously is not the solution I'm looking for.

Post by **Kilrah** » Mon Jun 18, 2012 9:15 pm

I have read about someone who fried one of the processor's input ports by sending an excessive voltage into it when doing a mod, that's pretty much what the result was.
Are you sure you never made a wrong connection?

rperkins · Post by **rperkins** » Mon Jun 18, 2012 9:24 pm

If I recall there are trim harnesses for each gymbal/joystick. Can you plug the trim harness from the working side into the socket of the non-working side ? this could determine if the trouble is in the harness or in the main board.

sberri wrote:Another quick note, unplugging the trim harnesses from the board eliminates the lockup problem but that obviously is not the solution I'm looking for.

sberri · Post by **sberri** » Mon Jun 18, 2012 9:36 pm

@ Kilrah No wrong polarity or voltage wiring issues. I'm beyond anal when it comes to that kind of stuff. I do understand the question has to be asked. Asked others that question hundreds of times over the years.

@ rperkins there are two harnesses, one for each stick. the connectors however are different sizes so a quick flip flop isn't possible. I can do a little MacGyvering to make the swap possible. hang on for a few while I get to riggin'.

sberri · Post by **sberri** » Mon Jun 18, 2012 10:27 pm

okay, swap finished. problem stayed on left stick. I'm going to go over the boards with a fine toothed comb. I have a feeling though that I won't find anything. In an attempt to stay ahead of the curve, I'll be presented with two options after finding no physical circuit problems......1. buy a smartie board for $35(out of stock until mid Jukly) and hope flashing fixes the issue or 2. buy an Ersky9x board for $95(in stock), thus solving the issue and getting a kick ass upgrade at the same time...a penny for your thoughts

Post by **Crucial** » Mon Jun 18, 2012 10:37 pm

I'm confused as to why flashing it or replacing the mainboard will fix it if the problem stays with the trim buttons. It sounds like you should be emailing the parkeflyer guys and asking them to repair it or send you a replacement gimbal.

Also, you aren't limited to just the smartie parts board if you want to reprogram it. If you have basic soldering skills you can get a programmer for $5 and solder in a cable.

sberri · Post by **sberri** » Mon Jun 18, 2012 11:25 pm

I think you misread my results...the problem stayed on the left side of the board. I tried swapping just the trim boards and harnesses as well as the complete gimbals and netted the same result...whichever one got plugged into the left stick board interface had the problem while the other unit worked in the right stick board interface.

which cheap programmer do you recommend ?

rperkins · Post by **rperkins** » Mon Jun 18, 2012 11:55 pm

sberri wrote: which cheap programmer do you recommend ?

Well glad you got it narrowed down, sorry it is on the main board. maybe you can remove one pin at a time from the plug and see if that helps. really I havent looked at your problem or the board enough to say any more.

I have been using these cheap chinese USBASP. Depending on whether you want speed in shipping or low cost, this seller Industryland has been good to me. Dont buy one, buy 2. that way you can reflash one with the other if you want to put custom or at least known firmware on it. These chinese ones come with a locked version of the firmware that does autospeed. If you want a seller closer to your location , these particular units are identified by having the microcontroller set at a 45 degree angle referenced to the board edges. this appears to be the source as betemcu.cn resolves here http://item.taobao.com/item.htm?id=17718224418

http://www.ebay.com/itm/USBASP-USBISP-A ... 407wt_1165

Post by **Crucial** » Tue Jun 19, 2012 4:49 am

http://www.hobbyking.com/hobbycity/stor ... duct=21321

This one works well.

Post by **Kilrah** » Tue Jun 19, 2012 6:48 am

Do a thorough inspection/cleaning of the main board. Some found solder residues around the processor pins that were causing shorts.

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