View Full Version : No Drive, only reverse!

2007.04.18, 11:41 AM
My iWaver worked fine when I got it out of the box and I was driving it around then the drive went... So I took it apart to see the problem and a power cable came off the motor...

So I thought "I'll just wait until my new motor arrives".

But ofcourse, I couldn't wait and tried my mini-z motor in it and still the same thing happened. What's going on? I thought it was one of two things.

Drive FET has gone
Something has come loose

Any help would be appreciated.

2007.04.18, 11:51 AM
ok, a bit of confusion.... you looked and the motor wire had come off? if so thats the problem. if you assumed it had and it actually has not, you fried the fets.

2007.04.18, 11:57 AM
Sorry I should have been more clear. The motor wire fell off and I thought "Oh, that's it, that's the problem", but when I put another motor in the same thing happened.

So this must mean it's the drive FET?

2007.04.18, 12:35 PM
I'd say you're bang on Tommy boy from what you've described to me and what you've tried. Upgrade time?


2007.04.18, 12:50 PM
Before assuming its the FETs check and see if the motor wires are stable on the board. Check other connections as well.

Ive now owned 2 Iwaivers and 1 Firelap. Every single one of them had multiple loose connections and took some soldering to get the to work correctly. I just got the two Iwaivers and the guy that sent them to me had to resolder the servo wires for there to be any steering. They were NIB when he bought them and he had never taken them out of the box until checking them before sending them to me. Ive had to resolder the lead from the power switch on one and resolder the motor wires on the other.

On my Firelap one of the motor wires just fell off. When I changed over the a kyosho motor, I noticed that the positive lead from motor to PCB wasnt real tight. Come to find out it wasnt connecting hardly at all, and was causing my car to cut out at times. More soldering....its now permenantly attached and running pretty well.

Bottom line, these thing arent the quality of miniZs and I dont even think have the quality control of xmods. More than likely (from my experience anyways) there is a loose connection causing your problem.

2007.04.18, 12:58 PM
Thanks for that, great reply!! I've had a look and I can't find anything out of the ordanary, although the connections do look ready to go!!

Everything looks fine to me... Can anyone else spot a problem?


2007.04.18, 01:07 PM
^ Looks pretty decent to me. The black wire going out of the top of the pic looks a little stressed :D

The reason I notice it is because it was one of the wires I had to resolder on my Firelap. It comes from your batteries though, so if its real bad, you wouldnt get power to the steering either. Its just in a position to get kinked and pulled off, and the solder doesnt look real good around where its connected.

Are the motor wire screws tight when you screw them in?

2007.04.18, 01:22 PM
As tight as I can get them. :S I'm miffed. Must of certainly fried the drive FET.

2007.04.18, 01:55 PM
Im not saying you didnt. I just wanted you to check out the simpler stuff before you go trying to change them out :D

I guess I shouldnt go against the experts around here :p

2007.04.18, 01:59 PM
Hmmm... I wanted to avoid a FET upgrade too... Oh well... May as well make it a good one!! :rolleyes: :D

2007.04.18, 03:23 PM
Tom, perhaps we should have updated this thread a little before hrdrvr started his queries on the rest of your Iwaver board! As you yourself know, my diagnosis was based on chatting with you via MSN Messenger, about what was happening and what to check before I posted here, hence me stating 'from what you've described to me and what you've tried' in my post. Just helps to avoid people going through the same stuff and not having the intel on what's already gone on behind the scenes.


2007.04.18, 04:23 PM
Yeah, good point. Sorry.

2007.04.18, 08:16 PM
FWIW, there is no such thing as "the drive FET", or a "forward FET" or a "reverse FET". Power for forward drive goes through both drive FETs, and power for reverse also goes through both FETs. Each 8-pin "FET" actually has two MOSFETs devices, one N-channel, and one P-channel. If you blow the whole IC (two MOSFETs), you lose both directions. If you've lost one direction, then it's likely that only one MOSFET is bad, or has a bad connection. I would touch up the solder joints first. Be sure to remove your batteries first.

At least this is true on MR02's, and I'd be shocked if it's different on any of the others.

Also, if you lose a wire off the motor, you'd lose both directions. Current doesn't flow through the motor in either direction unless both wires are connected.

2007.04.18, 09:04 PM
lol, I was wondering when someone was gonna post this, but nobody has, so here goes. On the far right of the pic you posted, there are 2 FETs. The one towards the top has a white blister/bubble on it. that one is fried. FET replacement is necissary.

2007.04.19, 03:11 AM
Thanks guys. :) I'm getting it sorted. :D

2007.04.19, 03:51 AM
I'd dismissed that as a spec of something on the FET, as I thought it would have been the first thing you'd have queried if it was bubbled! LOL!


2007.04.19, 07:10 AM
^ Me too! I thought it was a spec of dust based on the debris across the rest of the board :/

No prob as far as me asking a bunch of questions. I came up in sales and qualifying customers got me into asking a lot of questions before I begin to help some one :lol: I guess old habits die hard.

2007.04.19, 11:09 AM
The company are replacing the car free of charge! So I should have a nice new one soon.

Thanks for your help everyone! :D

2007.04.20, 04:30 AM
hrdrvr, lol. You sales guys. Made me realise though to remember to include any privately discussed info into a public post, so it's all good.

Tom, Pleased to hear you're getting it sorted - the company sounds helpful, as Mal also was able to get a transmitter changed over without sending the complete readyset back.


2007.04.20, 04:38 AM
Yeah, I was thinking they probably make a lot of money and if we're lucky... MAYBE, they might just send us a whole new kit back. I've had similar experiences in the past. I hope so. :D