Tekin Mospower esc problem

[Sunseeker]

Hi everyone,

I have recently bought a buggy that came with a Tekin Mospower esc. I think it may be the Pro version? I have connected it to a modern 2 cell lipo battery and a 2.4 ghz receiver and I am having a problem with it. It has had the on/off switch removed, so as soon as the battery is connected it gives the motor what seems to be full power or very close to it. I can get it to slow a little by using full reverse/brake on the transmitter, but it's not by much. I have tried reversing the throttle signal and adjusting the trim on the transmitter. I have also tried the adjustments on the speed control it self. Also are the Mosfet and Mospower controls closely related? I can find a manual for the Mosfet esc, and it seems that they may need specific adjustments to me made to the transmitter depending on brands?

Is my speedy faulty or have I missed something? Any help would be very much appreciated.

Peter

[Bormac]

I've found in the past that once a trim pot on these old esc's are overturned they can create problems. Not sure this is the case here but something to consider. I love these old esc's.

[Sunseeker]

Thanks Jason, the adjustment dials feel fine to me but I will keep in in mind. It would be great to get it going properly it looks like a nice speedy.

[urban hype]

I would check the drive fet's. Your speed control most likely does not have any brakes and the brake fet's are blown. For some reason when the brake fet's are blown it will run full throttle only. I have had several esc's with this problem.

[Sunseeker]

Thanks urban hype. Is that hard to do? It sounds like it might be above my skill level. I can do basic soldering but that's about it.

[urban hype]

To change a FET is not very hard but first see if the fets are good in the first place. The easiest test is done with a digital multimeter. Use the resistance (Ω) setting. Place - probe on of the three pins. Pick any other pin for the + probe. The number might be small something like .00001 but there must be some sort of resistance. If you get 0 open or ∞ the fet is blown. Test each one individually. You can have 1 bad fet in the bank and it still can work. If you need to change a fet you should get the right tool. It is not too hard to overheat the pad and destroy the board. I suggest you get a tool like SH-60. Here is a link so you can see what it look like.

http://www.a1parts.com/solomon/index.html

I have used all methods and tools that are available and this is the best tool by far.

If you need to change the fet you will have to get the number from it to get a replacement. Kevin Orton was a bit of a nut job and he would sand the numbers off of the case so the competition would not know what parts he used. There is a possibility that the number is missing off of the case. If it is missing you may have a hard time getting a replacement. There are usually cross reference replacement parts but you will need a identical package for it to work.

I hope this helps you.

[Sunseeker]

Thanks urban hype for taking the time to reply to my post. I have a Digitech multimeter but I don't know very much about how to use it, so I'm sorry if my results seem wrong or don't make a whole lot of sense.

I set the meter on resistance (Ω) setting 20K and noted the readout at neutral, full forward and full reverse of the transmitter. The bank of six (forward?) had a neutral reading of 14.15, a forward reading of 2.22 and a reverse reading of 14.12.
The bank of two FETs (brake?) had the same reading of -17.00 at neutral, forward and reverse.

Thanks again for all of the information you have posted,
Peter

[urban hype]

Sunseeker, you should do the readings with no power. With the unit live it is rather easy to slip with the probe and cause a bunch of problems. Retry the readings with no power. Please post the result .

[Sunseeker]

Ok, did I just break the No.1 rule for using a multimeter?

This will get confusing for you and my terminology will be all wrong, but I will try to explain it as best I can.

If I use the 20K setting I get a reading of 1_.___ before touch the probes on any of the pins. I started by placing the - probe on the outermost pin of the bank of six FETs and then placing the + probe on one of the two parallel pins (as you explained earlier). I repeated this across the six FETs to the bank of two FETs, the reading of 1_.___ does not change until I make a connection from the common track of solder (the centre line for the bank of six FETs and also the top line for the bank of two FETs) and one of the two four remaining pins from the bank of two FETs. At this point I get a reading of 0.21 and a reading of .000 if I test without using the common track.

I then repeated the process but now used the 2M setting. The reading was .705 for the bank of six and .000 for the bank of two (no matter what two of the six pins I tested).

I then repeated the process but now used the 200K setting. The reading was 1__._ for the bank of six, 00.2 for the bank of two when using the common track and 00.0 for the bank of two without using the common track.

I then repeated the process but now used the 2K setting. The reading was 1.___ for the bank of six, .213 for the bank of two when using the common track and .001 for the bank of two without using the common track.

Does any of this make any sense? I'm in over my head on this one

[urban hype]

Ok, did I just break the No.1 rule for using a multimeter?

Yes, if you can help it, do not work on anything electric while it is live.

You have now done the test correctly. From the information that you have posted it is as I thought the brake FET's are blown. This is a common problem with these old speed controls. ESD was not a well known fact at this point in electronics manufacturing.

This is repairable if you can get the correct FET. If they did not sand the number off you can cross reference the part number and get a new parts.

[Sunseeker]

I promise to keep the knife away from the toaster from now on

I can see some numbers on the side of one of the FETs , so it looks promising. This may take me a few weeks to do, but I think I will give it a go.

Thanks again for your help urban hype,
Peter

[slapshot1979]

This is a really good info thread. Good work guys

[urban hype]

I can see some numbers on the side of one of the FETs , so it looks promising. This may take me a few weeks to do, but I think I will give it a go.

Just remember that in most cases the drive fets (the bank of 6) are different from the brake fets (the bank of 2) Also if you get a chance please post the fet number so that others that have broken speed controls can have a chance to repair them.

[Sunseeker]

Hi guys,

I have removed the brake FETs from the circuit board. There are quite a few markings on the FETs, There is a "B" on the heat sink, "100163" on the top of the face, a "M" on the centre of the face, "F721" on the side of the face and "G D S" above the legs?

From what I can see of the the drive FETs they have the same markings. Unfortunately I damaged some of the printed circuit during the removal so I don't think I will continue to try and fix this speed control.

Thank you urban hype for you help,and hopefully this may help someone else out.

[urban hype]

Sunseeker, All is not lost till you see fire! You may be able to bridge solder the fet if you damaged the trace. If you can post a picture of the board and fet. Hopefully I can help you to get this old girl going again.