Small / Micro sized ESC help needed

[rcs2die4]

HI All,

This is a bit of a help needed / ESC wanted post !!! :smiley14:

I have a LRP QUANTUM REVERSE ESC here that I got second hand to try
and get my M18 back on the track!!

I got it knowing that the forward side didn’t work but was told the reverse
side worked perfectly and the previous owner said he just swapped the wires
around and used the reverse side as forwards !! which was cool by me as I
only wanted to go forwards anyway and just really wanted to get the car going
again !!!

Apon installing the ESC I noticed that the reverse side only works for a
maximum of 8 seconds then it cuts out and you have to go back to neutral
to reset it and then go again !! (safety feature for reverse !) Which makes it
basically useless…

So this part of the post is for the FET techs out there !!
Can any of you help me out with getting this going again ?? I pulled
it apart and of cause there were a few blown FET’s. I have removed them but don’t know which FET’s to get to fix it (or where to get them) or if I can
replace the FET’s for different ones !! The FET’s that are in it have 4420
written on them as did the two I removed… any help would be great !!!

Now to anyone and everyone !!
Does anyone have a micro sized (around 26mm x 26mm) ESC they would like
to sell or swap for something of interest ?? it’s for my M18 which has a
Speed 300 motor in it… Can be Forward/Brake or F/B/R, Not to concerned
about the brand !! same as above, any help would be great !!!

I would prefer to fix mine but shit happens, if I have to get a another one then so be it..

Thanks Guy’s

[klims]

first off 4420 doesnt really mean much on its own. usually there is something like IRF7201 written on top in the setup

I*R P537H
4V0P
F7201

meaning that IR(international rectifier) is the manufacturer and F7201 is the part number. when you google “IRF7201 datasheet” and open the datasheet it will tell you all you need to know about the mosfets. ie: n-chan or p-chan.
with this info you can select a mosfet that will suit you needs/budget.

if all that is written on the mosfet is 4420 then it may be a little more difficult. i’ve seen it similar on some elcheapo ESC’s before. your gonna need to work out whether the blown ones are N or P chan with a multimeter. do you have the skills?

[Dangerous Dave]

I was doing some learnin about FETs. seems alot of the rc popular ones eg IR7317 are dual n/p?

Matching the package type should be easy (SOT 8 or whatever).

[rcs2die4]

Thanks guys,

OK all thats writen on the fets is

some have

4420
5DWA <– the 5 looks like an S or 5 it's in a different font and the A is more of a symbal that looks like a letter A
.W012

some have

4420
5D1A
.W006

and some have

4420
5BTA
.W952

I have a multimeter but I’m not sure how to test for N or P chan.. any help with this would be great !!!

The ones that were blown were to blown to do anything with but once I removed the bits that were left the PBC and
tracks are fine !!!

L8R

[klims]

considering what PH2T told ya 1y ago they may be Si4421DY mosfets, meaning they are N-chan. not sure how your ESC works but i’m thinking there should be a h-bridge in there.

you confuse when you say “some have”… how many are there? maybe a photo would help.

personally i would use my multimeter to find out exactly what they are, n or p, and take it from there.

the ( . ) you included in the description on the mosfet tells you which is pin1.

open this link and click on any one of the data sheets. you will see the ( . ) you were looking at on the picture. so now that you know what it looks like and you have the pin configurations here is how you check whether the mosfets are n or p chan.

as seen in the pin layout in the data sheet, pins 1-3 and 5-8 are connected together inside the mosfet, leaving pin 4 on its own. if you look at the track layout on the board of your ESC you should see something to that effect. if your lucky they might even be bridged just as you would when doing a stack. this is just a check to make sure your looking at the right pin, pin 4.

now that you know which pin 4 is, you can measure its voltage with respect to ground. pin 4 is the activator pin that tells the mosfet to either open of close the connection from one side to the other, source (S) to drain (D), pins 1-3 and 5-8.

so now grab a pen, turn the ESC on and in the neutral position measure and record the gate voltages of each of the mosfets. be very careful not to bridge any of the pins while doing this. you could fry the mosfet. better yet see if you can follow the track to another component like a resistor or something that you are less likely to fry.

now that you have measured and recorded the gate voltages at neutral, do the same with the trigger in the full forward position and again in the full reverse position

oh i should also mention that the esc only needs to be hooked up to power, not the motor.

how was that? do you follow?

Andrew.

[rcs2die4]

Yep, I follow and I’ll give it a go !!!

I’ve attached a link to a pic of the PCB !! The ESC is two layered,
this is the top PCB… The two plates beside are little heat sinks they are
lined up beside where they go !!!

the other side of this PCB has about the same amount of Fets but they still have there heat sinks on

The ESC specs are

voltage input is 4.8 to 8.4
On Resistance is 0.0038ohm
current rating is 1 sec 70A
30 sec 45A
5 min 30A
PWM Frequency 2100 Hz

http://i23.photobucket.com/albums/b362/RCS2DIE4/My%20Xray%20M18/P1020144.jpg

thanks again

[klims]

yep as you can see in the photos there is a single thin track going to pin 4, the gate. if you measure that voltage your set.

just for reference, those chips are an S-08 package

[rcs2die4]

OK Excellent, will sort that out ASAP !!

For the instrum with that pic or if I send you some more pics of both sides of the PCB would you be able to tell me if I could remove two of the fets from the reverse side so I could put them on the forward side as just so I can get it going for now, till I sort the rest out ????

I know it’s a bit dodgy but I really just want to have a go as it’s been over a year since I’ve had my M18 running and as A mate of mine is a HPI Micro in the next few days I want to be able to have a run with him !!

Thanks again

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