Main board problem, Looking for some advice

[Miracle Boy]

Hi Guys,

My Nano main board has a new problem, Might be a dry joint somewhere.

It sort of looks like a bind issue i.e. it is a PITA to bind and when it does it cuts out on spool up, (Blue LED turns off, then comes back on again after a few seconds), but with one small difference.

If I can get it to spool up to ful head speed, sometimes, but not every time, just before it cuts out I loose all tail authority as the tail motor either stops or runs at full speed for maybe half a second before tail and main cut out and LED goes off.

Could this be a failing tail FET? I was under the impression that when a FET goes it usually burns out, and the tail FET looks ok.

I have re-flowed all the joints on the RX chip, and all the joints on the gyro, thought it was ok, I test flew 5 lipo's in the house and it was fine, took it to my flying site & the fault is back again

I'm confident that the joints I have re-flowed are fine now, I have fixed the "won't bind" issue many times before by reflowing joints, but I can't seem to get it sorted this time around.

I'm rather subourn and refuse to give up on a faulty board.

[Russell Harding]

Megasmicros.com

$25 repair and back to you in just over a week.

[NCcraig]

What TX? My DX7 does some weird things with nanos from time to time. No clue why and it use to do the same thing when I owned a 130X. No problem with the rest of my helis.

[Miracle Boy]

Originally Posted by Code3Medic

Megasmicros.com

$25 repair and back to you in just over a week.

Thanks Code3medic, but I live in the U.K. so postage would be a killer, sendig the board back and forth. I may well contact Kevin & Megamicros though, He's been gracious enough to help me out with advice when I've had probels in the past.

[Miracle Boy]

Originally Posted by NCcraig

What TX? My DX7 does some weird things with nanos from time to time. No clue why and it use to do the same thing when I owned a 130X. No problem with the rest of my helis.

Hi NCCraig, I'm using a DX6i with the Nano, never had any problems with any other heli with it. It might be that it's just something that's happening because I've mybe been inputting some rudder at the time it happed as I was trying to spin the tail back around as I always lift off tail in.

I'm really not sure, this board has been repaired so many times now it's silly. It acts like a common fractured solder joint issue to me, but maybe since it's been reflowed so many times something has broken down inside the silicone Rx chip. Many months ago, when I was still learning how to reflow the joints properly, I broke one of the legs off, along with part of the track. I did a "wire add" repair to what was left of the leg by adding a tiny piece of magnet wire, that's where it always breaks now in a crash, since it's a weak spot. Heating and cooling so many times since when doing a repair, maybe the Rx chip has just had enough.

I think I'll remove the conformal coating on the big controller chip on the back of the board and reflow that. Every joint under that conformal coating looks bulbus and dry, but that's lead free solder for you

Maybe it's something else, like a cracked SMT capacitor or resistor, IDK

But I refuse to give up on it!! I wonder if I could maybe get a new Rx chip and replace it? Do you know if it has to be programmed in any way to work?

[rcdave13]

Recently saw someone in UK selling repair services on ebay.

[Miracle Boy]

Originally Posted by rcdave13

Recently saw someone in UK selling repair services on ebay.

Thanks rcdave13, I appreciate your pointing that company out to me. I've had dealings with them in the past when I had a mSRX that had board isseues too (bought second hand) and via e-mail they were pretty much non-comunicative. I would only send my board to a company I feel I can trust, and sadly, I don't feel I could trust them.

Like I said though, I appreciate the thought!!

[NCcraig]

Originally Posted by Miracle Boy

Thanks rcdave13, I appreciate your pointing that company out to me. I've had dealings with them in the past when I had a mSRX that had board isseues too (bought second hand) and via e-mail they were pretty much non-comunicative. I would only send my board to a company I feel I can trust, and sadly, I don't feel I could trust them.

Like I said though, I appreciate the thought!!

May just have to break down and buy another board.
I have bought a few for around $30 used.

[Miracle Boy]

Originally Posted by NCcraig

May just have to break down and buy another board.
I have bought a few for around $30 used.

Hey NC, Yeah, I bought a spare board a while back, but what I don't have is servos and motors etc to allow me to continue to try to keep messing around & try to fix it.

The last few months have been mental at work, but that's me on christmas holidays starting today. Off for a few weeks now, so maybe I'll be able to get some more time to try re-flowing more solder joints and hopefully figure it out.

My BL is down a/w carbon rod to make a new boom, and my Trex 150, that's been a disaster staight out the box, not impressed with that at all!!

If I figure it out I'll update this thread. I've not written to Kevin (@Megasmicros) yet, maybe he'll be able to point me in the right direction if he's not too busy.

Cheers!!

[puretech]

code3medic Can you fix my nano?
Thanks!
-Dwayne
760-207-0547

[-רחל]

I had similar probs when I was flying with a DX6i. I sent the TX to HH and they swapped a pot, the 2,4GHz module and antenna.

Check the servo monitor on your DX6i
Maybe you'll already discover something weird there.

[DPW]

Mini Plug Extension for Micro Battery 10cm (5pcs/bag) $2.22
Replace
Battery connector
Could not find a identical replacement for the battery connector but these extensions work.

[Miracle Boy]

Thanks for the advice guys

I've still not been able to get my little Nano sorted, I now seem to have probs with the motor spooling up, but it might just be that I've not soldered the motor BL motor wires to the XP3A ESC that well, it was a rush job late last night in the hope I could get it flying today. Solder joints are "spikey".

At spool up the rotor head turns maybe 270* and then stops and sort of vibrates like it's trying to go backwards then forwards really quickly. Sometimes it spools up o.k. then shuts down as the rotor head gets up to full speed and the main board blue LED goes out for a few seconds, then comes back on again. It's got me thinking..

What does the main board do if I have an intermittent short in the BL motor wires? Would that cause the main board to shut down? The FET's on the ESC look fine and I've not touched the signal wire from main board to ESC & it looks fine too, but if the enamel has worn though on one of the motor wires somewhere, might that be the cause of my intermittent shut downs?

Thanks!!

[-רחל]

1) I don't know if that's your problem but it looks like after plugging in the battery you have to arm the motor by short pushing the throttle stick and pull it back again (you hear 2x beeps)

2) If you have a short then your board may shut down due to over current protection.

Your batteries are good?

3) Throw away that lead free crap!

[Miracle Boy]

Originally Posted by -רחל

1) I don't know if that's your problem but it looks like after plugging in the battery you have to arm the motor by short pushing the throttle stick and pull it back again (you hear 2x beeps)

2) If you have a short then your board may shut down due to over current protection.

Your batteries are good?

3) Throw away that lead free crap!

Thanks for your reply

I've not had another chance to look at my little Nano, but it arms just fine and batteries are good. It might well be an intermittent short in the motor. When I get a chance to carry out further investigation I'll update the thread.

I'll prob try another main board & see how I get on with that.

Cheers!

[Miracle Boy]

Just a quick update, I wrote to Kevin @ Mega's Micro's and he thinks that the problem might be a faulty 2.7v DC (LDO) voltage regulator for the Rx chip.

I've ordred various replaement parts from Kevin, but does any body know where I can get one of those sooner (they are shipping from the US to the UK so that will take about 4 weeks)

If anyone can provide a link to a datasheet for the right part I can use the info too track one down from a UK supplier and keep the parts ordered from Kevin as spares.

Thanks!!

[Miracle Boy]

Well, I think I have found the correct part. It's a MCP1700t-2702E/TT Made by Microchip Technology. It can be found bellow.

http://www.digikey.co.uk/product-sea...00t-2702e%2Ftt

Annoyingly I can't find a supplier for it here in the U.K. AT ALL. Not unless I were to buy a minimum of 3000 of them!!

[Bhujang]

I bought a load of upgraded fets for my xp03 from them and it arrived very fast. They do have a .co.uk website but still ship from the US. Arrived in 3 days! But did cost $12. Hope you get it sorted. Let us know how you get on...

[4712]

Originally Posted by Miracle Boy

Well, I think I have found the correct part. It's a MCP1700t-2702E/TT Made by Microchip Technology. It can be found bellow.

http://www.digikey.co.uk/product-sea...00t-2702e%2Ftt

Annoyingly I can't find a supplier for it here in the U.K. AT ALL. Not unless I were to buy a minimum of 3000 of them!!

Forget the MCP1700t-2702E/TT.
They will work somehow, but not as good as the originals.
The original ones are much better in filtering voltage peeks from the power line...
Better than this, would be to use the 3V line for the 2.4Ghz chip.

Best solution: Take the LDO from a servo Board!

[Miracle Boy]

Sorry 4712, I've only just picked up this thread again

Thanks for your reply I didn't know I could get away with using the 3v line to power the 2.4ghz Rx, good to know!!


Anyway, I got the 2.7v Reg from Kevin at Mega's Micros. Fitted it, but I still have the same fault as described above.

I had sort of admitted defeat with the board and fitted a new board and XP-3A ESC. The fault is gone with the new board and ESC fitted, but I'd still like to try and repair my original board if possible.

Now that the Nano is working properly, I have now realized something that may be quite significant.

With NEW board in place, When I arm the ESC (gov arm mode) by moving the throttle from min to max and back to min again, the tail motor will gradually get faster as I increase the throttle. (normal behavior)

With the FAULTY board, as I raise the throttle to arm the ESC, once I get to about 15% throttle the tail motor starts to spin up, but it is not a gradual increase as I move the throttle stick up like it should be, the tail motor jumps straight to full speed.

The tail motor will still respond to commands from the AS3X as the tail motor will start and stop if I wave the tail boom around, and it will also stop if I move the rudder stick (I can't remember if it stops with left or right rudder input)

It's like the inputs from AS3X or rudder stick are acting purely as an on / off switch to the tail motor.

I was under the impression that if a motor FET is blown, the tail motor would run at full speed regardless of any other command from rudder or AS3X. Is my understanding wrong?

Would a faulty tail FET,cause the power to the tail motor to be simply on or off?

This is with a stock brushed tail motor BTW, not a brushless tail motor!!

Any advice anyone can offer about this would be very much appreciated!!

Thanks!!