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View Full Version : Stacked fet's?


JamesJozef
2006.05.19, 10:29 PM
Since I'm a bit of a noob to mini z's,i was wondering if I'd need to go with stacked fet's to run this http://cgi.*******a/ws/eBayISAPI.dll?ViewItem&item=250000037097&rd=1&sspagename=STRK%3AMEWN%3AIT&rd=1 motor in an MR-01. If I need to go with stacked fet's, is their a tutorial for it for the MR-01? Wich fet's would I need if I were to stack them?

Draconious
2006.05.19, 10:39 PM
if you have to ask such questions, you will need to find some one to do it for you...

JamesJozef
2006.05.20, 10:08 AM
Har Har. Why couldn't you have just told me, instead of just dismissing me as inferior (which I most likely am), and actually try and answer my question?

JamesJozef
2006.05.20, 12:10 PM
Sorry to double post, but are there any tutorials out there for stacking the fet's on an MR-01?

Fish
2006.05.20, 02:22 PM
byebye has a video here: http://www.minizracer.com/forums/showthread.php?t=19645

That should help you figure out what you're up against.

JamesJozef
2006.05.20, 03:23 PM
Thanks. That's gonna help alot.

*Edit* Argh! I can't get them to play. Can you put them on google video? Or maybe putfile? That would be very greatly appreciated.

ph2t
2006.05.20, 07:14 PM
JamesJozef, help yourself, don't be lazy and stand on the shoulders of others...

Just download the latest windows media player to play those WMV files from www.microsoft.com

Also the mosfets you want are either Si4562 or IRF3717, they re both the same interms of performance. You will need to buy them from somewhere, several mini-z stores sell them. I get mine from http://shop.ausmicro.net

There's a simple rule of thumb to be used in determining if a motor requires a fet stack and that's if the motor is less than 45turns then you'll need at least a 2x2 stack, if the motor is below 30 turns, then you're better of with a 3x2 stack. That's about it and don't stack any higher than a 3x2 since your throttle response will get choppy.

You know, did you ever try the search function? Most likely that's all that Fish did. As I said, help yourself and don't sit on your arse waiting for answers from everyone. Then you may get better responses.....

ph2t.


ph2t.

JamesJozef
2006.05.20, 08:39 PM
Well, I have ,edia palyer, Although I have an issue with it, and haven't been able to find the uninstaller. And I did search, and found a topic where the links took me to a search engine. Well, anyways, I got the video to work, and I've removed the first fet, however, I am have ing trouble with the second one (the one close to the big black thing, i have no clue what it's called), is this usually a problem or is mine just being difficult?

byebye
2006.05.21, 10:50 AM
It's usually a problem but just take your time. My video is Crude and was done late at night. If you add a little solder to the iron it will help melt up the solder on the board making it easier to remove. Just use some solder removing mesh to clean up the pads.

-Byebye

JamesJozef
2006.05.21, 07:33 PM
It's usually a problem but just take your time. My video is Crude and was done late at night. If you add a little solder to the iron it will help melt up the solder on the board making it easier to remove. Just use some solder removing mesh to clean up the pads.

-Byebye

Ya, I'm folowing that vid, except with a 15 watt soldering iron, It's slow, but I think theres less of a chance of burnig the board. If I can't get it out, I'll try snipping the legs off it, and heating them seperately, and pulling them out individually with tweasers. I touch that big black thing witht he soldering iron a tiny bit, and melt the plastic the smallest little bit in one spot. Have i damaged it, or is it only the cover I've damaged.

Thanks for all you guys' help, andI'll try and pull out the second one in a lil' bit.

herman
2006.05.21, 10:14 PM
do a search on "fets" and you get this result...
http://www.mini-zracer.com/forums/search.php?searchid=493149

luckily some dude compiled some sort of fet guide (a bit old though)...
http://www.mini-zracer.com/forums/showthread.php?t=10419&highlight=fets+101

read through it, i'm sure you will be able to pick up somthing... hope this helps... :D

byebye
2006.05.22, 01:50 AM
If you hit the black box even quite a bit and it won't damage it. I have a couple that are pretty beat up. You can use some of that aluminum tape and wrap it up.

-Byebye

JamesJozef
2006.05.22, 11:54 AM
Well good news and bad news. Fet came out relatively easily. Unfortuntaely it took t2 of the pads out with it. Is the board ruined? If it is, I'm screwed untill I can aford a new one, and I'd buy one with them already stacked. anyone have an MR-02 board with stacked fets that they will sell?

Spoon
2006.05.22, 12:02 PM
Well good news and bad news. Fet came out relatively easily. Unfortuntaely it took t2 of the pads out with it. Is the board ruined? If it is, I'm screwed untill I can aford a new one, and I'd buy one with them already stacked. anyone have an MR-02 board with stacked fets that they will sell?

Which two pads did it take out? Do you have pictures?

If the black box is on the left, Pin 1 is the top left on the chip from there the numbering goes counter clockwise, like this.

1 8
2 7
3 6
4 5

It depends on which pads you lifted but it may be salvagable (sp?).

JamesJozef
2006.05.22, 12:23 PM
Salvagable?

byebye
2006.05.22, 12:26 PM
Well that sucks!

-Byebye

JamesJozef
2006.05.22, 12:33 PM
Not salvagable?

Spoon
2006.05.22, 12:36 PM
Sorry dude, I think you might be screwed. If it were two pads on the right side (5-8) you probably would have been ok since they are all connected.

I don't know if this (http://www.egrracing.com/mart/product_info.php?cPath=21_27&products_id=897) is a decent board or not, but it's pretty cheap. And I think it has a single layer of upgraded FETs on it. It will be faster than what you had on there.

JamesJozef
2006.05.22, 12:43 PM
Ah screw! I won't be able to buy anothe rboard for a while because I bought a nealy $200 model the other day. I'd be looking to upgrade to an MR-02 board, so I can run lithiums.

sciencemike
2006.05.22, 05:09 PM
It sucks you pulled those fet pads off. They are the only two really essential ones! Pins 1 and 3 control the fet 2 and 4 are the power lines, then 5-8 are the output side pins.

Im looking for some salvaged parts off some boards. If you consider trashing the board ill take it off your hands.

JamesJozef
2006.05.22, 06:00 PM
I'll trash it, sure, coz it's no use to me, how much are you willing to pay for a trashed board, coz I'm looking to buy aboard with already stacked FET's, but I'm a little low on cash.

sciencemike
2006.05.22, 06:20 PM
Ill give you 10 bucks shipped?

Or, if you would rather i can do the fet stacking service for free for you. Just get me the fets, and the board and ill do your next one.

E mail me for the deal.

Mreid at Caltech dot edu. Just replace the @ and .

JamesJozef
2006.05.22, 06:22 PM
I'll think about it. You think I'd be able to send it in an envelope? Boards are hard coem by up here in canda.

sciencemike
2006.05.22, 06:47 PM
Think about it. ill throw in another 5 for you to ship it properly.

JamesJozef
2006.05.22, 06:54 PM
It's gonna cost me that much to ship it properly.

sciencemike
2006.05.22, 07:00 PM
Is that a deal then? E mail me when you decide.

Shipping shouldnt be too hard, just wrap a big wad of tissue paper around it and throw it in a padded envelope. Shipping should be about 2-3 bucks.

JamesJozef
2006.05.22, 09:16 PM
A new board comes with the switch, and all the wires, that go into the servo and everything, or do I need to save any of that when I remove the board?

sciencemike
2006.05.22, 11:26 PM
Your new board should come with everything. A board, servo motor, pot, and a switch.

For example if you buy the atomic board that has fets on it. It comes with a board, servo and a steering motor and a pot and a switch.

Heres a link. Its a cheaper brand of board.

http://www.egrracing.com/mart/product_info.php?cPath=21_27&products_id=897

It comes to 32 bucks and has everything installed.

SuperFly
2006.05.23, 12:46 AM
Um, I think that board is salvagable, but you'll need a multimeter (or just a cicuit-checker will do), some small guage insulated wire for jumpers, and patience.

If you can find even just a shred of the trace where the pad lifted off, touch one end of the circuit-checker to that trace, and just start checking the vias (the little round metal holes) down at the other end of the board. Once you find another connection point, solder one end of a jumper wire into the via, and the other to the leg of the FET where the pad lifted off.

Here's a thread where I did a similar thing with an MR02 board, and some of the results of my testing. I fixed that board and it's been running fine for over a year.

http://bitpimps.lixlink.com/pages/phpForum/viewtopic.php?t=6838

Spoon
2006.05.23, 11:18 AM
@ SuperFly

You might be right and I almost mentioned this but (and no offense) if he couldn't remove the FETs, I think he is going to have a hard time trying to do that kind of rework. I used to work with a guy that could do something like that in his sleep but that was a former life.

That would take some soldering skills, patience (like you mentioned) and a decent iron with a small tip.

imxlr8ed
2006.05.23, 11:31 AM
Yeah... tiny jumpers like to dance around when you get the heat to them, it's a real pain. If it would've happened anywhere else on the board it's alot easier to deal with, but trying to lay clean jumnpers when you're up against the box is near impossible. I just gave up on a board with the same situation just this weekend... real bummer. :(

JamesJozef
2006.05.23, 04:36 PM
@ SuperFly

You might be right and I almost mentioned this but (and no offense) if he couldn't remove the FETs, I think he is going to have a hard time trying to do that kind of rework. I used to work with a guy that could do something like that in his sleep but that was a former life.

That would take some soldering skills, patience (like you mentioned) and a decent iron with a small tip.

No offence taken, I've already tried, and zero luck. The board in the minizracer shop comes with everything?

JamesJozef
2006.05.23, 06:44 PM
I meant the stage 2 spec 2 board. I was tired whn I replied... Stupid thing won't let me edit my post.

ph2t
2006.05.23, 08:16 PM
James, I could fix it for you if you'd like. As superfly said, it's a matter of finding the right jumpers. I did a lot of work on this in the past and have alternate signal points mapped out. If you interested just shoot me an email at ph2t at netspace.net.au (at = @). Cost would be for fixing + shipping back to you + mosfets = $25USD.

cheers,

ph2t.

SuperFly
2006.05.23, 08:42 PM
James, I could fix it for you if you'd like. As superfly said, it's a matter of finding the right jumpers. I did a lot of work on this in the past and have alternate signal points mapped out. If you interested just shoot me an email at ph2t at netspace.net.au (at = @). Cost would be for fixing + shipping back to you + mosfets = $25USD.

cheers,

ph2t.

Lol, if he doesn't want it, I'll take it! $25 is a bargain for a kyosho board with upgraded fets.

Let me add that while you can get iwaver boards (which I suspect that EGR board is) for about the same price, they are nowhere near as good. They are much more prone to twitchyness, and the granularity of the proportionality is not even half of a Kyosho.

ph2t
2006.05.23, 08:54 PM
lol, so you've got a bung PCB too mate? Just shoot me a PM at bitpimps. I was going to ship out a refurbished nelly for hue shortly as well.

ph2t.

SuperFly
2006.05.23, 09:31 PM
lol, so you've got a bung PCB too mate? Just shoot me a PM at bitpimps. I was going to ship out a refurbished nelly for hue shortly as well.

ph2t.

heh, no all my boards are fine, but I'd still pay $25 + shipping for a repaired Kyosho board. So I guess I'm half recommending JamesJozef spend the $25 and get it fixed and half saying that I'd take it off his hands if he doesn't want to. ;)

Speaking of stuff, should I be expecting a package to ship to you, ph2t?

JamesJozef
2006.05.24, 09:56 AM
$25 is a good deal. That's USD, right? Do you have paypal or something? If you do, email me where to ship it to, and how to pay for it. My email is onyschuk at shaw.ca

JamesJozef
2006.05.25, 09:26 AM
As soon as I get an emil telling me how to pay for it, and where to ship it to, I'll ship it out. emil is onyschuk at shaw.ca (at=@).

SuperFly
2006.05.25, 11:55 AM
As soon as I get an emil telling me how to pay for it, and where to ship it to, I'll ship it out. emil is onyschuk at shaw.ca (at=@).

Click the link in ph2t's signature, you can probably find an e-mail addy there.