MM Pro BEC not holding voltage under load - Page 2 - RC-Monster Forums

BrianG · 12.15.2009, 06:00 PM

Depending on the duration, amount, and frequency of the bursts, you might even want something like 3300-4700uF.

Unsullied_Spy · 12.15.2009, 06:08 PM

People run caps about that size on their ESCs to help with ripple current, is it really necessary to run that much on the Rx?

SpEEdyBL · 12.15.2009, 07:11 PM

I guess I will try a novak 2700 uF 25V cap that I have lying around. Or will that draw too much current when charging? My main concern is whether I will have this problem if I buy another MM Pro. The one I have now was for my touring car, though I tried it in my 8ight to see how it would work. Also, like I said before, another person running the exact same servo doesn't have this problem.

whitrzac · 12.16.2009, 12:55 AM

I ran 6600uf and was still able to get the transponder/RX to cut out... in a t4/6.5 on carpet with a bms617 servo and MRT transponder, not stressing the esc by anymeans

I wouldn't mind paying a few $$ more to have a WORKING bec

J57ltr · 12.16.2009, 01:06 AM

Do you have an Eagle Tree datalogger or can you borrow one? You can measure Servo current with it.

Jeff

BrianG · 12.16.2009, 01:55 AM

Wow, I wonder if there is something wrong with either that servo or the BEC? ~2.5A with a cap that size should have solved it.

whitrzac · 12.16.2009, 09:31 PM

Quote:

Originally Posted by BrianG

Wow, I wonder if there is something wrong with either that servo or the BEC? ~2.5A with a cap that size should have solved it.

the bluebird servos draw ALOT of current...

the MMp isn't the first esc to cut out when useing them, the stock SC10 esc will also do it.

I know for a fact that the MM will not cut out.

BrianG · 12.16.2009, 09:37 PM

That's because it's a linear regulator. They tend to be more bullet-proof, but also heat up a LOT more especially with higher currents and higher differential voltage.

Arct1k · 12.16.2009, 11:18 PM

i have a servo guage tester which measures peak and ave servo draw...

whitrzac · 12.17.2009, 12:43 AM

Quote:

Originally Posted by Arct1k

i have a servo guage tester which measures peak and ave servo draw...

I should pick one of those up for my eagletree..

.

Pdelcast · 12.17.2009, 12:53 AM

It's entirely possible that there is a bad chip, cracked solder joint, etc. etc. Feel free to send it in for a checkup.

Patrick

BrianG · 12.17.2009, 12:53 AM

You can easily make your own. Simply take a servo extension lead, cut the red and black wires somewhere in the middle, and put connectors on them that match whatever you have on the ET wires.

whitrzac · 12.17.2009, 09:11 AM

Quote:

Originally Posted by BrianG

You can easily make your own. Simply take a servo extension lead, cut the red and black wires somewhere in the middle, and put connectors on them that match whatever you have on the ET wires.

I know you can use a yharness to find servo position, but in order to measure amps I thought you needed one of these

http://www3.towerhobbies.com/cgi-bin...?&I=LXSDX4&P=7

BrianG · 12.17.2009, 11:14 AM

Yes, that will work, and can probably measure smaller currents more accurately, but a simple Y harness can be used to measure voltage and current just like how it would measure ESC current.

03.06.2010, 12:44 AM

I just bought a new align servo for my 10th scale rt5 its model DS610 i connected it to my mmp and the reciever started to lose power when turning fast. This is with no load on the servo. I also have a JR 9100 high torque servo which i tried on the mmp and had no problems, this was just to test the BEC with a known trouble servo. So at this point i assumed I had a bad servo but when i connect it to the rx8 in my 8ight it works fine. This servo is smaller than my JR and does not have nearly the torque. What is going on? Was the fix mentioned earlier in this thread about adding a delay ever implemented in new mmps. Should I send the mmp in?