kevenoco

My Feedback: (1)

Hi,
I am reviving an old Traxxas Rustler (1995) with an Tekin Titan ESC and Orion Rush 15T motor, Futuba Magnum Junior Radio but having trouble getting reverse to work properly using the SET button on the ESC (QuickTune setup).

I accidentally soldered both + & - leads to the same side of the motor and of course it did not work, so I resoldered to correct this. I reset the ESC with QuickTune before testing it out. Now forward works but reverse does not. It acts like the "reverse bypass" is on. Braking works fine.

With full Reverese:
When motor is disconnected I get negative volts coming from ESC.
When motor is connected I get 0 volts. I think this is how the braking works? (If motor is not turning then no more negative volts otherwise you would go in reverse)

I checked the motor. It will run in reverse if you hotwire it backwards, so I know it's not a motor issue.

I also checked the Throttle channel on the RX by hooking it up to a servo. Reverse works fine on the servo.

I am wondering if I am missing something during the Quicktune setup (after light starts blinking I go full forward, full reverse, then neutral). I've tried multiple settings on the reverse delay from 0 through 4 seconds as specified, but nothing works. It always acts like it's on Reverse Bypass.

Did I short out something in the ESC? Would braking work if I shorted something?

Below is the link to the manual. Any help is very much appreciated.

Keven





[link=https://docs.google.com/viewer?a=v&q=cache:SWTThso6j2QJ:http://www.competitionx.com/pdf/esc/...L1rVJKOw]Tekin Titan Manual[/link]

DieHarder

Well, I think I found your problem. According to page 12-13 (The wiring diagram) and your picture, on the ESC, you soddered the motor wires to the battery terminals, and the battery wires to the motor terminals. So simplified, the wires are mismatched.[:@] So your esc is freaking out because the power is coming in on the motor terminals, and not the battery terminals. So you need to resodder the wires. Once you have the wires resoddered, please post a picture to I can confirm it. Then run it through the QuickTune process and see if it works. Please keep me updated!

Be sure when resoddering, you scrape the sodder off (after heating it up) and add new sodder so it doesn't end up being a cold joint.

kevenoco

My Feedback: (1)

DieHard,
Thanks so much for your help. I rechecked my wires and I think they are correct. The picture is confusing because it looks like the battery cables are going right into the motor but they're not. Sorry about that. I've attached a better picture.

Keven

DieHarder

Oh....sorry.  Um...Geee....I really don't know what's wrong. You may have a faulty ESC. I'd take it in to a hobby shop.

EXT2Rob

My Feedback: (1)

Is there some sign from the ESC that confirms the Reverse Delay setting?  It still sounds like by-pass mode.
OR, is there a "double-tap" you have to do for reverse to work? As in full-reverse once is brake, second stab activates reverse?

kevenoco

My Feedback: (1)

Thanks EXT2Rob,

The manual does not mention any indication of Reverse Bypass. I have tried setting the Reverse Bypass deliberately but everything still acts the same (brakes work, no reverse, same LED signals).

The double tap method is not a feature of this ESC as I was just driving the car right before I reset the Quicktune feature and it just has a simple delay that's adjustable from 0-4 seconds.

Keven

DieHarder

So your saying that after you brake to a complete stop, you try reverse and nothing happens? (The double-tap theory)

kevenoco

My Feedback: (1)

That's correct. Brakes work fine and I have tried everything I can think of but no reverse.

EXT2Rob

My Feedback: (1)

It's beginning to sound like something in the ESC is not working properly.  Major bummer, I know. 
WAIT!  Just thought of something......when you did the quikset thing, did your throttle trim on the transmitter happen to be not centered?  (I'm reaching)  You might try PM'ing FOXY. He's pretty knowlegeable.

kevenoco

My Feedback: (1)

Thanks EXT2Rob. I did make sure that the throttle trim was centered but no luck. I'm going to disassemble the ESC tonight to see if anything looks burnt. I will follow up.

Thanks!

Keven

DieHarder

Maybe a bad sodder joint on the inner circut board?

kevenoco

My Feedback: (1)

I took apart the ESC. I can see a lot of amber build up and a weird white blob of something. Maybe that's supposed to be there? I'm afraid to scrape it off.

kevenoco

My Feedback: (1)

Here are comments from Nick Marson, a designer of ESC's.

From yesterday:

"I suspect that one of two things is wrong:

· The sense circuit has blown

· One of the 4 sets of FETs has blown. You can get forward and brake with just 3 sets of FETs being functional

Generally when FETs have blown you can see a tell tail. Look at the junction of the FET, where the metal tab and the plastic meet. If you see what looks like solder beads, then the FETs have blown. Did you note a smell similar to an overheated transformer? Another way is to remove the ESC case and look to see if the FET have cracked bodies."

Today:

"It looks like you will need at least 2 off SMP60N03 MOSFETS. These weren’t around when I was still active..."

"If you replace the 2 FETs there is a good chance that the controller will work, no guarantees however."


Thanks a lot Nick!

Keven

nosram

Keven,
The picture isn't too clear, but it looks like the solder may have reflown under the suspect FETs. This would be consistent with the small balls leaving the crime scene as it heated up!
No attempt was ever made to remove the excess flux, which makes getting a good picture even more difficult.
Nick Marson

kevenoco

My Feedback: (1)

I think I noticed that too. I wire brush cleaned the bottom of the circuit board and noticed some solder where it isn't supposed to be but I did not take a picture. I will tonight and post it.

Keven

DieHarder

Ok, that greasy stuff is conductive grease. It's put there to make a ground or a better connection. I say scrape it off because it's not supposed to be used on ANY circut boards. It's probably not only touching the terminal it's supposed to, but maybe some others. It could be shorting two terminals together. Since the components on a circut board are soo small, the grease is hard to get on one terminal. And from what I see there, it looks like someone just dumped a glob on. I really think you should scape all remains of it OFF. That isn't right. It doesn't look factory put there either. Any broken parts should be replaced.

kevenoco

My Feedback: (1)

Here is a picture of the bottom of the circuit board. You can see some solder from a battery terminal spilling over into an adjacent trace. I've ordered MOSFETs too. We'll see what fixes this thing.

SyCo_VeNoM

that "spill" don't matter
looks like it might have been meant to be connected, and even if it wasn't the coating on the board should prevent it from making a connection. Not good practice but I've seen it done on boards just like leaving the excessive flux(also not a good thing to do as some can cause corrosion)

martijefre

Once you have the wires resoddered, please post a picture to I can confirm it.

DieHarder

Hey! You trying to mock me?!

EXT2Rob

My Feedback: (1)

Yeah Keven, that amber colored stuff is solder flux. You can clean it off with rubbing alcohol. DON'T use a wire brush!!! Toothbrush will suffice. 

How good are you at soldering, and what kind of iron do you have?  Unless you have some experience removing soldered components from circuit boards, you could be in for a frustrating time with those thru-hole FETs, and a few burnt fingers. Be careful, go slow.  In order to remove one of those FETs, you're going to have to heat ALL THREE pins at once. That can be tricky if you haven't done it before, you'll feel like you need three hands, and you just might. Just be careful not to ruin the board.  Good luck!

kevenoco

My Feedback: (1)

Thanks EXT2Rob
Several people have told me not to use a wire brush but it was too late.

I fixed the solder that was spilling over into an adjacent trace and retested the ESC. Still the same problem. Nick is going to help me replace those MOSFETs. He is highly qualified. I bought them off Ebay ($22/qty 4) and they will arrive by Friday next week. I will post the results.

Thanks for everyone's help.

Keven

SyCo_VeNoM

Hate to tell you that it would have been cheaper, and easier to just order a new ESC like a XL-5, and you would have known for sure it worked, and not tinker with this one which might have more wrong with it.
I know sometimes its just the principle of making it work, but you also hae to know when to call it quits in this hobby or the cost will explode fast, and you will be left with either something inferior, or non operative (this is just in general holds true for nitro motors, RC's, and RC parts like the electronics)

kevenoco

My Feedback: (1)

You are so right. The economics on this one totally do not add up. This is mostly for pleasure. I would not recommend to your average guy to do electronic repairs on something like this. I love fun projects like this. I hear you though. At some point I will call it quits.
Keven

SyCo_VeNoM

ahh so its a more just cause I can approach then
I know how that is I'll be honest I repair some stuff, and people wonder why I keep resurrecting old things when I could just chuck it and get a new one.