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Z_408
2006.05.21, 11:42 PM
Hello,

I just picked up a few MZM's and one of them is having some issues. It worked fine the first few days. However today it does not have any response to throttle. The steering works fine. I have messed with the throttle trim with no luck. Sometimes it will only work in reverse. I have also messed with the A-B position with no luck. Should they work on either? Please let me know if I need to return this one.

thanks,
Z_408

im8im8
2006.05.22, 04:34 AM
Did you race them? I encountered a similar problem after I raced my bone stock enzo. After my most recent race, the throttle just stop working. I had the throttle on full not thing responed at the motor however the steering worked. I then checked the connection to the motor and that was fine. Then I took a screwdriver and tighten up the two screws that mounted the motor wires to the PCB. I was able to tighten it arount a quarter turn. After that the throttle control was back to normal.

Z_408
2006.05.22, 12:16 PM
No racing, just bashing. Sometimes when I turn off the TX, it will go in reverse, but when I turn the TX back on it will not respond.

Spoon
2006.05.22, 12:27 PM
You could try a couple of different things.

Swap the transmitter (if you have another one)
Swap the crystals (not likely the problem if steering works)
Check motor wires (at the circuit board and the motor itself)
Swap the motor

If none of that works, you could have a fried or loose FET. You can pull off the top cover and look at the FET's. If there is a really small raised bubble on one of them, it's fried.

If the FET's aren't fried, you could try pushing down lightly on the FET's while you pull the throttle. If you have a loose connection, it may connect and start working.

If it's a FET problem, you are going to need to fire up a soldering iron. I would HIGHLY recommend getting someone to do it for you or you could end up damaging the circuit board beyond repair.

Z_408
2006.05.22, 12:52 PM
Spoon,

Thanks for the reply, I have tried to swap the TX and crystal with no luck. I will check the motor next. If it is the fet, I will not do it myself.

thanks for the info, I will keep up updated.



You could try a couple of different things.

Swap the transmitter (if you have another one)
Swap the crystals (not likely the problem if steering works)
Check motor wires (at the circuit board and the motor itself)
Swap the motor

If none of that works, you could have a fried or loose FET. You can pull off the top cover and look at the FET's. If there is a really small raised bubble on one of them, it's fried.

If the FET's aren't fried, you could try pushing down lightly on the FET's while you pull the throttle. If you have a loose connection, it may connect and start working.

If it's a FET problem, you are going to need to fire up a soldering iron. I would HIGHLY recommend getting someone to do it for you or you could end up damaging the circuit board beyond repair.

rharris
2006.05.23, 01:18 AM
I just ran into a similar problem with my stock race car.

After 5 months of racing almost every weekend, and running time trials twice a week for the last two months, the forward throttle will not respond.

I checked the radio, crystals, motor connection (even tried another motor). I took the board out of the car to inspect the FET's and they seem fine. The board was a bit dirty but I can not see any visible damage.

I don't know what else to check.

Thoughts?

Spoon
2006.05.23, 11:24 AM
Hey Z,

I was just wondering if you had any updates on the state of your board...

Rereading your post it looks like you just got these. If you got it new, the best bet would be to return/exchange it (if you can). Also, if you got it stuck somewhere or it was against a wall or something while you were holding the throttle then something like that would fry a FET.

I think there are a couple of members in CA that would offer the same services, but if it's a FET problem, I can replace or resolder the FETs for you. You might just need to track down some FETs, I don't think I have any spares.

Email me if you are interested.

Z_408
2006.05.23, 12:28 PM
Spoon,

I did purchase the Monster new. I know for sure I did not hold the throttle down when it was pinned against a wall. I barely went through a set of batteries. It actually happened when I first turned it on, but it went away.

I took the board apart yesterday and touched the FET and put it back together and it worked for about five minutes. I also tested the motor by putting a multimeter on the terminals off the board and pressing the trigger. No response.

So now I am assuming that it is the FET. It is a bummer because I got it over the internet and shipping it back and forth would cost some change. Do you know how much someone would normally charge to change out the FET?

Also should the Monster work on both the A and B setting?

thanks for all the info,
Z_408



Hey Z,

I was just wondering if you had any updates on the state of your board...

Rereading your post it looks like you just got these. If you got it new, the best bet would be to return/exchange it (if you can). Also, if you got it stuck somewhere or it was against a wall or something while you were holding the throttle then something like that would fry a FET.

I think there are a couple of members in CA that would offer the same services, but if it's a FET problem, I can replace or resolder the FETs for you. You might just need to track down some FETs, I don't think I have any spares.

Email me if you are interested.

Spoon
2006.05.23, 01:27 PM
Spoon,

I did purchase the Monster new. I know for sure I did not hold the throttle down when it was pinned against a wall. I barely went through a set of batteries. It actually happened when I first turned it on, but it went away.


Cool, the holding-throttle-while-pinned thing is usually a young child thing, but I thought I would mention it.

From everything else that you mentioned it does sound like it could be a bad solder joint on a FET. I am on the other side of the country but I would fix it at no charge if you wanted to ship it to me. I have done a couple of FET replacements for some of the local guys.

There may also be a member closer to you that would be willing to do it. I think ScienceMike is on your side of the country.

Either way, if you can get someone to do it, I would recommend just going with the upgraded FETs you can get from the shop here.

http://shop.tinyrc.com/product.php?productid=16723&cat=0&page=1

You could just get two of them and replace the two stock FETs on the circuit board. Your monster would be a little faster and have a lot more acceleration. You could also get a reasonably priced 2 x 2 stack from the shop for $35.

http://shop.tinyrc.com/product.php?productid=16793&cat=0&page=1

Of course if it's just a bad solder joint, it could be fixed in a second by reheating the solder. It's hard to make a call without seeing the board.

Anyway, if you wanted to strip everything off of the chassis you could probably Priority Mail ship it anywhere for about $4.

I hope I am not overwhelming you with options. Let me know if you have any questions.

and oh yeah....1000th post :cool:

Z_408
2006.05.31, 08:42 PM
Cool, the holding-throttle-while-pinned thing is usually a young child thing, but I thought I would mention it.

From everything else that you mentioned it does sound like it could be a bad solder joint on a FET. I am on the other side of the country but I would fix it at no charge if you wanted to ship it to me. I have done a couple of FET replacements for some of the local guys.

There may also be a member closer to you that would be willing to do it. I think ScienceMike is on your side of the country.

Either way, if you can get someone to do it, I would recommend just going with the upgraded FETs you can get from the shop here.

http://shop.tinyrc.com/product.php?productid=16723&cat=0&page=1

You could just get two of them and replace the two stock FETs on the circuit board. Your monster would be a little faster and have a lot more acceleration. You could also get a reasonably priced 2 x 2 stack from the shop for $35.

http://shop.tinyrc.com/product.php?productid=16793&cat=0&page=1

Of course if it's just a bad solder joint, it could be fixed in a second by reheating the solder. It's hard to make a call without seeing the board.

Anyway, if you wanted to strip everything off of the chassis you could probably Priority Mail ship it anywhere for about $4.

I hope I am not overwhelming you with options. Let me know if you have any questions.

and oh yeah....1000th post :cool:

Spoon,

Thank you for all the information and you offer to help. I have contacted the company I purchased it from to see if they could help. I will keep you upated.

thanks,
Z_408