3LikesTekin RX8 1/8 Scale Brushless ESC Thread
02-26-2010, 02:13 PM
#6781
After all, other than heat or shock/vibration, I don't see what could kill the ESC if they didn't make any stupid design errors. One problem that could happen would be if the temperature sensor detached from the MOSFETs and the heatsink also began to detach. Then the MOSFETs could fry without the thermal shutdown kicking in. Or maybe they put the sensor on the heatsink, which would be dumb. How securely is the heatsink attached to the MOSFETs?
One other thing is that MOSFETs are really sensitive to static electricity. If they didn't put some ESD diodes on the inputs, that could eventually cause flaky operation leading to failure. To prevent this you can wire up a "Tranzorb" diode across the battery input terminals.
One other thing is that MOSFETs are really sensitive to static electricity. If they didn't put some ESD diodes on the inputs, that could eventually cause flaky operation leading to failure. To prevent this you can wire up a "Tranzorb" diode across the battery input terminals.
Both are ESC's are well built and have plenty of copper on board to support the heavy current burst.
I do use additional TVS and caps on most of my ESC's as I use A123's. The voltage spikes during braking can be high when running near the voltage limit of ESC's.
02-26-2010, 02:17 PM
#6782
i only race in the winter and theres no doubt in my mind that at the end of this winter my esc will still have the same issues it has now and i will put it away for the summer and come back to race next winter it will break again the first time i use it and its out of warranty already so it will be waaaay out of warranty and im not paying to get it fixed so we can start this whole sending it in for repairs every two weeks again for it just to break again, again, again ,again and again if it was the first time it broke sure but it doesnt even last a month. so guess i will have to save up this summer for a mamba for next winter because im done with tekin they have lost me as a customer
02-26-2010, 02:47 PM
#6783
At the end of the day, speculations/assumptions can be made and preventive measures be put in place. But you won't really know exactly what the issues are unless Tekin releases a list of failures (and causes) that they've seen so that the community can implement their own fixes temporarily, or in this case, "band-aids" to the problem. There are just so many ways that a piece of electronic device can fail whether it be due to user error or not. The preventive measures that tetris suggested are a step in the right direction, but again, at the end of the day, you won't really know if you're fixing anything since no one seems to know what the root causes are in the first place.
02-26-2010, 03:33 PM
#6784
oooh i forgot the last time it failed (my red heat sink rx8) i was using this stuff as a mount
http://www.amainhobbies.com/product_...ng-Gel-1-Sheet
http://www.amainhobbies.com/product_...ng-Gel-1-Sheet
02-26-2010, 03:43 PM
#6785
02-26-2010, 03:43 PM
#6786
DING DING DING. We have a winner. (most of the time, we all know that there are excptions) & Tekin has told us this (I think even in this very thread). Internal solder joint failure.
Tetris, I'm sorry for my comments to you but I've been fooling with E-1/8 for almost 3 years now. I've worked in eletronics for a living for 25 years now and have more than a bit of real world failure analysis experiance. I've dicected MMM's & Tekins (under the microscope). I'm not basing my opinion on what I've read in these forum but rather on the failed hardware I've inspected & communications I've had with Patrick & Jim.
02-26-2010, 03:55 PM
#6787
I have seen a few MMM combos fail (i have two and they have been 100%) one was from a huge jump out of a skate park.. im talking huge air, as fast as a 8ight-t could jump out of the bowl. and the other was in a flux.. but im almost 100% that that thing was cooking wrong gearing and the HPI and traxxas products that come with this stock seem to have way more drag than the race truggys..
So like you guys have said the RX8 just needs a bit more time to be 100%.. and when its there I will pick one up.
So like you guys have said the RX8 just needs a bit more time to be 100%.. and when its there I will pick one up.
02-26-2010, 03:59 PM
#6788
lol no no i love the tekin system and i like it better than the castle ....... its just that i "hate" that i have to keep sending it in for repairs other wise i think its superior to castle............and tekin did tell me every time i sent mine in for repair that it was a solder problem on the circuit board something about the board not being in the oven long enough? or something like that..........tekin dont make me buy a castle. i dont want to but if mine keeps failing i will have to.
02-26-2010, 04:11 PM
#6789
Well, if you want to get really crazy you could manufacture a little foam box that goes up to the bottom of the heat sink. One thing that works well for vibrations and shock is "lead foam". Its layers of lead and foam.
At first, I was thinking about just mounting it with 1/8" 3M foam mounting tape. But now I'm thinking something even better like 1/4" with a layer of vibration dampening gel/rubber, with some hot glue on the sides of the case to keep it from flopping around. There's got to be some way to mount it sufficiently well that solder joints aren't likely to crack....Well, if only the Mamba Monster was sensored, life would be easier. I bought one recently and immediately returned it since it was my first experience with brushless, I was taken aback by the lack of smoothness compared to brushed motors.
EDIT: Actually, the more likely explanation for cracked solder joints, considering that John_stu already mounts his well, is thermal expansion. And, unfortunately, you can't do much about that. They would need to redesign the layout so that when it heats up and cools down many times, it doesn't eventually crack something.
Maybe one could mod the fan to keep it running cooler. For example, hardwire it on 100% or run it at a higher voltage.
Last edited by tetris; 02-26-2010 at 04:56 PM.
02-26-2010, 04:28 PM
#6790
Lotts of MMM's died for the first months, now not so many but I like the Tekins better.
On the FET's, most of any brand ESC's that burn are going to be due to FET failure. Infant mortality of the FET itself or poor gounding (solder) or over heating due to user error incorrect set-up.
Most the Tekins I've seen fail just stopped & have been repaired by replacing the little bottom board(not where the FETs are).
It will all get worked out.
On the FET's, most of any brand ESC's that burn are going to be due to FET failure. Infant mortality of the FET itself or poor gounding (solder) or over heating due to user error incorrect set-up.
Most the Tekins I've seen fail just stopped & have been repaired by replacing the little bottom board(not where the FETs are).
It will all get worked out.
Last edited by RBMike; 02-26-2010 at 05:49 PM.
02-26-2010, 08:32 PM
#6791
My failure's went like this........First round of practice on a Working set-up, roughly 2 or so month's old with a couple races under its belt (1900kv on 4S 5000's) all of a sudden the thing cuts out....Drake picks it up....all of a sudden its alive again....drive it a couple more turns....dead.
Bring it back to the pits...check it out....something's up with the ESC.......talk to a fellow losi E guy who says try a Rx pack on the RX to see if its the BEC......Sure as shi* it works....but there's no place to rig a Rx pack anywhere safely so i Get the Tekno boys to swap it out for me (i had no soldering gear and wasn't prepared to do a swap)
Come back 15 min later they got my spare all wires up ready to go......next practice round is up.....fire it up...everything is kosher for the first min or 2.....make a couple laps.....it falls flat on its face again....this time the Rx pack will power up the ESC somewhat but now seems like something in the motor let go....(similar to one of my earlier failure's with something up with the motor or the rotor)....Pulled the end cap and cant see anything visibly wrong with it.
So here i sit with 2 Burnt out Rx8's and a Bum motor and this was on Practice day.
My set-up is as standard as you get....4S 5000's running 44/15 gearing....motor temps were no where near the danger zone and never got more then 2 or 3 lights on the ESC after a quali or hard run.
1 funny thing is Both the recent ESC's failed when i made a soft mount for the esc using Longer screws and foam underneath the ESC to give it a cushion....i dont think that was part of the failure.....but i did have it solidly mounted to the battery tray prior to.
Bring it back to the pits...check it out....something's up with the ESC.......talk to a fellow losi E guy who says try a Rx pack on the RX to see if its the BEC......Sure as shi* it works....but there's no place to rig a Rx pack anywhere safely so i Get the Tekno boys to swap it out for me (i had no soldering gear and wasn't prepared to do a swap)
Come back 15 min later they got my spare all wires up ready to go......next practice round is up.....fire it up...everything is kosher for the first min or 2.....make a couple laps.....it falls flat on its face again....this time the Rx pack will power up the ESC somewhat but now seems like something in the motor let go....(similar to one of my earlier failure's with something up with the motor or the rotor)....Pulled the end cap and cant see anything visibly wrong with it.
So here i sit with 2 Burnt out Rx8's and a Bum motor and this was on Practice day.
My set-up is as standard as you get....4S 5000's running 44/15 gearing....motor temps were no where near the danger zone and never got more then 2 or 3 lights on the ESC after a quali or hard run.
1 funny thing is Both the recent ESC's failed when i made a soft mount for the esc using Longer screws and foam underneath the ESC to give it a cushion....i dont think that was part of the failure.....but i did have it solidly mounted to the battery tray prior to.
02-26-2010, 09:19 PM
#6792
Guys understand that mounting does play a role in the failures, but may not be the root cause. So far nearly all of our failures are failed solder joints on the control board. It's not a loose physical connection rather a solder joint that gets a stress crack in it from the abuse we're subjecting it.
It's like a stress crack on a car frame. It's not any one jolt rather the multiple jolts that finally create the crack. This is also why it will work from one jump to the next. As the joint expands and contracts physically it will make a connection.
It is unfortunate that some individuals have more failures than others. I'm pretty certain that I run as much if not more than most of you guys and I've only had 2 or 3 fail on me at all. I run either Losi buggy or Truggy or my V8e Hotbodies car. I mount mine all the same, two layers of the clear parma tape.
The chassis slapping from REGULAR racing is a huge factor in these failures. The Rx8 should be abe to handle this. However this is why you will see more failures in buggies vs. truggies. The buggy sits lower and lands/slaps more frequently. I do think that a good majority of buggy racers do make the mistake of running gas car setups on their E buggy's. This will be too soft and underdampened because of the near 6 oz's or more that the e buggies carry. I personally went up one spring, 2.5wt in oil and on piston size smaller on my losi and feel that it's nearly identical in the handling of my gas version.
John Stu and others, we're working dilligently on resolving this and any issue that may come up. The guys running at the Motorama like Barry Baker, Andy Casetellini, Jason Ashton, Mark Calandara and other had not a single failure.
I do understand your frustration. We are racers too and realize that it sucks to have a good weekend of racing spoiled by a failure of anykind. Like I've said prior, we all normally carry some form of spares: servos,receivers,esc's, motors,etc. Brushless in general has managed to get this "bulletproof" label unfairly I believe. Anyone who's in the electronics industry will tell you that some failures are going to happen. And while we can strive for perfection, some failures are going to happen. It is unfortunate that some have had more than their fare share. WE are here to help you though and take each failure as a personal challenge.
It's like a stress crack on a car frame. It's not any one jolt rather the multiple jolts that finally create the crack. This is also why it will work from one jump to the next. As the joint expands and contracts physically it will make a connection.
It is unfortunate that some individuals have more failures than others. I'm pretty certain that I run as much if not more than most of you guys and I've only had 2 or 3 fail on me at all. I run either Losi buggy or Truggy or my V8e Hotbodies car. I mount mine all the same, two layers of the clear parma tape.
The chassis slapping from REGULAR racing is a huge factor in these failures. The Rx8 should be abe to handle this. However this is why you will see more failures in buggies vs. truggies. The buggy sits lower and lands/slaps more frequently. I do think that a good majority of buggy racers do make the mistake of running gas car setups on their E buggy's. This will be too soft and underdampened because of the near 6 oz's or more that the e buggies carry. I personally went up one spring, 2.5wt in oil and on piston size smaller on my losi and feel that it's nearly identical in the handling of my gas version.
John Stu and others, we're working dilligently on resolving this and any issue that may come up. The guys running at the Motorama like Barry Baker, Andy Casetellini, Jason Ashton, Mark Calandara and other had not a single failure.
I do understand your frustration. We are racers too and realize that it sucks to have a good weekend of racing spoiled by a failure of anykind. Like I've said prior, we all normally carry some form of spares: servos,receivers,esc's, motors,etc. Brushless in general has managed to get this "bulletproof" label unfairly I believe. Anyone who's in the electronics industry will tell you that some failures are going to happen. And while we can strive for perfection, some failures are going to happen. It is unfortunate that some have had more than their fare share. WE are here to help you though and take each failure as a personal challenge.
02-26-2010, 09:39 PM
#6793
Thx randy...I myself appreciate everything you do for us in regards to R&D to make these thing's solid....i 100% agree with you, that you run A lot more then the normal weekend warrior and you would obviously know what failing when they do....I know you guys are behind the product 100% and appreciate it 10 fold.
02-27-2010, 04:19 AM
#6794
