More 222 Gremlins

Lawrence Godson · Post by **Lawrence Godson** » Mon Oct 08, 2007 8:59 pm

Here goes with some new "challenges"

I'm still having issues with the sound system (Engine sound starting and shutting down randomly).----------but the new big issue is that yesterday I suddenly had the control system stop working. I was in a turn and everything suddenly stopped. No radio control of anything. Then it started up again and shut down again ---and over and over. Seems like attempting to make any type of turn tends to bring on the problem. Control usually comes back after a few seconds to a minute and I have all controls on all channels again ---but operating the steering servo will inevitably bring everything to a stop again. I recharged the rec. battery pack and checked all connections and anything mechanical that might be moving a wire when I operate the steering servo. Any ideas anyone? Is there some sort of circuit breaker that can trip out and then come back? Also at times the engine sound will spontaineously start while this problem is manifesting itself ---so the sound system is getting power.

Help!
PS All three lights remain "on" on the control box during the episodes.

Ad Wouterse · Post by **Ad Wouterse** » Tue Oct 09, 2007 12:08 am

Hi Larry,

Going through the Vortex 40 manual ( http://www.4qd.co.uk/instrs/PDF/vtx.pdf ) may give you some idea of what can go wrong.
I don't know if a thermal protection is included in the controller supplied by Armortek. Mark should be able to shed a light on that
My best guess based on your description would be the "current limit" protection. This is activated when a high current surge threatens do harm the mosfets. This may occur when the motor is close to getting blocked (your problem occurs in curves, is there any chance that part of the drive train locks up while steering ? ) or at start-up ( part of your problem too ).
Just my 2 cents.

Lawrence Godson · Post by **Lawrence Godson** » Tue Oct 09, 2007 3:19 am

Does the Vortex 40 control all RC functions including the sound system. It's interesting that at times when I've lost control---- the engine sound may start up and then I'm unable to shut the sound down (because, of course, it is also controlled by one of the channels and none of them are operable during this time). I'm assuming that the random engine start up problem is separate and possibly caused by interference---------but first I've got to track down this bigger problem......

Lawrence Godson · Post by **Lawrence Godson** » Tue Oct 09, 2007 3:22 am

One more thing......You said: This is activated when a high current surge threatens do harm the mosfets.

What is a mosfet?

Ad Wouterse · Post by **Ad Wouterse** » Tue Oct 09, 2007 11:48 pm

Larry,

The only "contact" between the controller and the sound unit is the data that the sound unit retrieves from the controller to adapt the engine sounds to the actual speed of the motor.
You mentioned that the 3 Leds on the switchbox stay on during the faillure. This means that the power is still on and this possible cause of faillure can be eliminated.

Mosfets are a special type of semi-conductors that are used to control currents in electrical circuits. They are in fact the components that regulate the speed of the motor. Although they are quite robust there is a limit to their capacity. For that reason a safety device called "current limit protection" is integrated in the 4QD controllers to prevent an overload.

As I mentioned in my earlier post, my gut-feeling says that something in the drive train is causing excessive friction or maybe even a full lock-up when entering a curve. This will lead to increased currents and may trigger the current limit protection to temporarily shut down the controller. I do not know what impact this can have on the other electronic components like receiver and sound system.

Adrian Harris · Post by **Adrian Harris** » Wed Oct 10, 2007 7:28 am

It may be unrelated but I get similar unexpected startup of the engine sound on my Sherman when the aerial wire shorts to earth due to the way I have the turret configured.

It may be worth checking if there is any damage on the aerial wire.

Adrian.

Lawrence Godson · Post by **Lawrence Godson** » Wed Oct 10, 2007 9:24 am

OK, I've not been able to get back to it for a bit but I intend to check evrything having to do with the steering before trying to operate again. Thanks for the information-----will let you know what I find.

Ad Wouterse · Post by **Ad Wouterse** » Wed Oct 10, 2007 11:45 am

Hi Adrian,

You may have a point there, the aerial should be fully isolated from any metal parts. Do you use a scale aerial or just the wire sticking out ?
Because Larry's problem seems to occur only when going through curves, my initial thoughts went in the direction of the drive train.
We will see what his findings are

Patrick O'Donnell · Post by **Patrick O'Donnell** » Wed Oct 10, 2007 1:09 pm

Lawrence,
Yes I think Ad is correct. I would suggest that the clearances are checked, especially the dog bone drive axles as they might be touching the the ladder frame on tight turns. Also check the diffs. in their Armortek metal cases as there could also be some binding there between the diff face and the case wall. You can tell if there is binding by checking the face of the diffs and case inner wall, you will see wear!

Patrick O'Donnell · Post by **Patrick O'Donnell** » Wed Oct 10, 2007 5:14 pm

Lawrence,
Another idea! Try running without the sound unit connected and if the 222 still stops in corners then it is most likely to be that the suspension, steering and diff. clearances need looking at.

Adrian Harris · Post by **Adrian Harris** » Wed Oct 10, 2007 5:20 pm

> Do you use a scale aerial or just the wire sticking out ?

A bit of both. I have one of John Grima's resin antenna bases, through which the aerial runs but as the tank isn't finished yet I haven't rigidly attached the antenna base. This means it periodically leans over and the metal part of the aerial touches the turret top.

You can see the aerial base in:

http://www.armortek.co.uk/gallery/main. ... temId=2487

Adrian.

Lawrence Godson · Post by **Lawrence Godson** » Thu Oct 11, 2007 5:06 am

Sorry didn't get to it today---trying my best ----"life" continues to cause delays.

Lawrence Godson · Post by **Lawrence Godson** » Fri Oct 12, 2007 3:24 am

I put it up on blocks today and removed the steering servo connection from the receiver. Problem gone ---- everything working fine (except of course for the steering).

Put steering servo connector into channel one connection (usually used for throttle) and throttle into channel two connection (normally used for steering. Problem returned with slightest deflection of channel one. (up /down motion of right joystick) Bad servo?
(wires to steering servo look good).
Larry

Allan Richards · Post by **Allan Richards** » Fri Oct 12, 2007 9:33 am

Lawrence,

All the troubles you have described point to a high current being drawn through the R/C circuit from the receiver battery. This powers the servo motors as well as the receiver circuit. When the current is too high the voltage on the receiver will not be sufficient and then you get all these funny seemingly un-related problems. I think you have got very near the bottom of the problem by isolating the steering servo, it sounds like the servo is either faulty and drawing a lot of current or its stalling out, not being allowed to move to full defection due to mechanical interference.

Post by **Armortek** » Fri Oct 12, 2007 10:02 am

Gentlemen

The servo supplied with the 222 simply does not have the current demand, even at stall, to cause the problems that Lawrence is describing, UNLESS, the receiver battery is nearly discharged. Even in these circumstances our test model does not demonstrate this effect. All that happens is the steering servo just fails to operate. Neither is the problem coming from the VTX40 speed controller because this device does not provide the output signal for the sound unit. Both the sound and the speed controller receive their signals directly from the receiver.

We have written directly to Lawrence to try to resolve his specific issues.

Mark