ESC repair, fried transistor- I need help from an expert!

[85Edinger]

Now I'm getting somewhere!
The guy I emailed turns out to be an extremely helpful electronics expert.

The transistor is a 2sb1184 i have a electronic business for 30 years do not sub this for a american transistor no ECG NO NTE STUFF THERE IS ALSO ZENER DIODES THAT WORK WITH THIS TRANSISTOR THEY NEED TO BE TESTED BEFORE YOU PUT NEW TRANSISTORS IN THE BLACK TRANSISTOR BEHIND THE 2SB NEEDS TO BE TESTED THEY ALL WORK TOGETHER MOST LIKEY THEY ARE BAD ALSO

[urban hype]

That is good to hear that you are getting somewhere. Bad to hear that there is no easy part substitution. You can go to some place like aliexpress where the would sell you a sample pack of 10 parts. That is a much better solution than having to buy a reel to get 1 part.

[jwscab]

I hate to say it, but you might be better off just finding a whole replacement esc, might ending up spending less time and money.

if you are heart-set on the esc case, maybe you can stick a newer smaller esc into the orginal case.

[85Edinger]

Ok. I don't have any real special attachment to this esc and I can easily afford a new brushed ESC, I just thought it would be cool to get this old one working.
Also, I went to do an FET test and realized that the FETs have no exposed wires to put a multimeter on.

[urban hype]

You do not need an exposed wire. You test from the bottom of the board.

[backlash]

dinger,

Does the esc work at all when you plug it in and turn it on??

Does the steering servo work.??

If nothing works when you connect the battery to the ESC (that is, motor and steering servo does not work) then the Mosfets could be OK, and the BEC could be what is blown.. You could try connecting that battery holder with 4AA cells to the receiver, and see what happens then..

If it starts to work, then add a little throttle and carefully check the temperature of the MOSFETS.. If the MOSFETS start to get really hot, then the brake fets could be short circuit, and this continuing to run the motor could also damage the foward fets as well..

If everything works OK with the 4AA batteries connected, and if that component is just part of the BEC, then you could just replace the 4AA batteries with an external BEC like the ones used in nitro / gas cars when using a LiPo receiver battery..

Goodluck..

[85Edinger]

Here are some tests I did.
Sorry about the picture quality. It's hard to use a multimeter one handed ant take photos with the other.
First, there seem to be two banks of FETs. On the left, there's a line of solder connecting (What I believe to be) the leftmost pins on the left bank of 3. The middle pins on the left bank don't actually seem connected to anything (?), they just stick through the bottom as three individual solder blobs. AS shown in the pictures, the resistance from each middle wire to the line of solder on the left was 3.9-4 megaohms.
What I believe to be the rightmost pins on the left bank (the third row from the left) is connected together by a solder line that then goes to the fifth row from the left.
I'm confused. From left to right, there's (1) a line of solder that starts at the red motor wire, (2) a line of 3 solder blobs, (3) a line of solder, starting at the black motor wire that is connected to row 5, (4) a line of solder starting at the black battery wire, (5) a line of solder connected to row 3, (6) a line of solder connected to the red battery wire, and (7) another row of 3 solder blobs.
Why are there seven rows? There are two banks of FETs, each has three terminals right? What's going on?
I just need to understand what I'm looking at a little better.
Sorry for the bad pictures. I just need to know what I'm looking at a little better.
Also, I tested the little black transistor next to the spot the burnt up transistor was.
Between the outer two pins, I got 3.25 Megaohms.
Between the middle and left pins I got 3.25 Megaohms again.
Between the middle and right pins I got 3.9 megaohms.
Thanks!
Backlash, the ESC used to power on when I tried to turn it on. The servo worked fine. I never got it to work quite right, the motor always either went forwards or backwards. Now it just won't power on- you saw that blown transistor.

[backlash]

dinger,

What brand radio gear are you connecting that ESC to?

I may have just worked out why the BEC transistor blew...

Take note where the positive wire goes in the servo plug...

[85Edinger]

I know what you're thinking. I used it with a compatible Airtronics receiver.
Good idea though.

[backlash]

dinger,

When MOSFETS fail, they usually fail Short Circuit, (close to zero ohms) between the Source and Drain terminal..

Again, if it were me, I would try powering up the receiver from a 4 AA battery pack, and ensure that the steering works.. You could also plug in a second servo, (or use the steering servo if it works) and connect it to the receiver where the ESC would normally connect, and test that CH2 on your receiver works also..

Then, with the ESC disconnected from the receiver (and motor) connect a 7.2V battery to the ESC, turn the ESC power switch ON, and test to see if you are getting any voltage between the positive and negative wire in the receiver plug.. The positive will have the red stripe, and the negative should be the middle/centre pin in the receiver plug.. I expect that you will get 0 volts... If you get 5 to 6 volts, there is no reason why the ESC should not power the receiver and servo in your car..

If the radio gear works OK, I would then connect the ESC (Without the 7.2V NiCd/NiMh/LiPo battery connected) and see if the ESC responds to the receiver.. I would expect that you may get some lights/LEDS to light, and that relay should click when going from forward to reverse..

If the ESC seems to respond to commands from the receiver, AND if you are getting 0 volts at the ESC's receiver plug, then I would try connecting a 7.2V battery to the ESC and see what happens... It may also be an idea to remove the motor pinion gear to save your car running away..

Not having your ESC here in my hand to look at makes it hard to determine how it is suppose to work, but after looking at your pics, and at a guess, I would say that one bank of MOSFETS are to control the speed, the other bank will be the brakes, and the relay is what changes it from forward to reverse...

The brake FETs will sit across the motor wires, and the speed FETs (Typically) will sit between the battery negative and the motor negative, although I would expect that the speed FETs will connect to the battery negative and then to the relay..

Thoughts..

[85Edinger]

Thanks for the advice. I think I can figure out the FETs now.
I think I will test the radio gear.

[85Edinger]

I tested the radio gear.
First I hooked a battery up. I turned on the controller, and the servo worked perfectly whether it was in channel 1 or 2.
Then I tested the voltage from esc + to - (BEC wires) with it turned on and a battery plugged in. 0. Just in case I wasn't clear, the ESC is dead- no lights, clicks, anything.
Then I pulled the ESC + and - wires out of its plug, and plugged just the signal wire into the receiver. With the battery plugged into the receiver but the 6s NiMh not plugged into the ESC, the servo worked but the ESC was totally dead.
With the ESC signal wire plugged in, a battery plugged into the receiver, and a battery in the ESC, with the ESC turned on, it was the same as before. The servo worked, but there were no signs of life from the ESC.
Attached is a picture showing the bottom of the ESC and the wires coming off of it. I still can't figure out why there are seven rows of solder. Any idea why two of them are just blobs while the other 5 are lines?
There were no dead shorts between any two rows, so does that mean all the fets are good?
I still need to test the diodes in the circled area. He said they were zener diodes, so I'll just test everything in the general area.
Advice or comments are appreciated. Don't assume I know anything, I'm in over my head.

[85Edinger]

I circled some of the diodes.
The one all the way on the right was 19.88 kiliohms one way and 19.47 kiliohms the other way.
The next from the right was 19.85 kiliohms one way and 19.39 kiliohms the other way.
Before I go on to the others I have to ask: am I doing something wrong, or are they both dead? I'm using a Fluke 73 Series II, set to resistance. I'm putting one probe on each wire (from the bottom of the board), recording the resistance, and reversing.

[85Edinger]

I've tested a few more diodes, including the one on the bottom. So far, every single one has the same resistance in both directions.
Could they all be either open or shorted?

[85Edinger]

Now I'm even more confused. I tested the diodes that gave the same resistance in both directions with the same Fluke multimeter on the conductivity setting, and that time they all gave conductivity in one direction but not the other.
I got conductivity between the middle pin and one outer pin on the black transistor immediately next to the spot where the burned out transistor was. It's code is M5236L, and below that, 7Y06. Here's the datasheet: http://www.datasheetarchive.com/M5236L-datasheet.html
So, is it good?
AS for the burnt up transistor, there are a few places here with a minimum order of 1.
http://www.alibaba.com/showroom/transistor-2sb1184.html