Electronical problems

[Marcel de Groene]

Hello guys,

It's been a while since I have finished my Panther. I'm back now because I'm experiencing electrical problems which I can't pinpoint to a specific part. I'm still running the "old" Amortek setup and using a Futaba 7 channel transmitter (one stick driving and turning)

Problem description:

Wenn I'm driving Panther seems to have less power on the right track. Driving and rotating the turret at the same time makes the Panther move jerky. Turning to the right, the Panther keeps turning to the right even if the controls are returned to neutral and I have to counter steer to get the Panther driving straight again.

I put the Panther on the bench to check this weird behaviour when running free. This is what I see. When giving full throttle the right track stops moving. Giving 75% throttle both track run but it seems that the right track is not running as fast.
I connected to servo to the left/right track channels to see if the servo's move different but both of them go to there max (left and right) Did this to check if it might be a transmitter problem. Also checked al the mixer settings on the transmitter and checked if some channels were setup less than 100% which wasn't the case. I also killed the mixer and tried two stick driving with the same result.
So it has to be something else.

My first thought would be the speed control units, but I don't have spares to check this. I think I'm using these in my Panther:

1x 4QD DMR-203 mixer controller
2x 4QD VTX 40-24 motor speed controllers

I hope some experienced similar problems and found a solution, because at the moment I can't figure it out and don't know in which direction to search.

Regards,

Marcel

[phil fitzpatrick]

Hi Marcel
Try putting some wood blocks under the floor plate to
raise the tracks off the floor and try pulling the tracks round to
see if there is any significant friction in the gear box on one side
and less on the other.
Cheers
Phil

[Marcel de Groene]

Hi Phil,

Will check this later today. What if this is the fact?

[Peter Silcock]

It could very well be a problem with one of the motors. Try switching the 4qds over so that the one operating the right track operates the left track.If the problem shows on the left track you know its the 4qd or the wiring to it. If the problem doesnt show on the left track when the wiring is switched over I think you will find it is a problem with the motor. I had exactly the same problem on one of my models. It turned out that one of the gears in the gearbox had slipped out of position.It was plastic! Returned it to Parvalux for pinning but if the gear itself is not damaged its a fairly easy fix to do yourself. I would think that the problem with the turret rotation is one of interference.I would try checking the wiring and plug the rotation into another channel on the receiver to seeif the problem persists.

[Adrian Harris]

This should be easy to narrow down.

The control of the track goes:

Transmitter -> Receiver -> DMR203 -> VTX40 -> Motors.

If you swap the left/right leads from the DMR203 to the receiver, and the problem swaps tracks, then the issue is with the transmitter or receiver. You will need to bind another transmitter to the receiver to eliminate the transmitter as the problem, and bind another receiver to your transmitter to eliminate the receiver.

If you swap the drive leads between the DMR203 and the VTX40 units, and the problem swaps tracks, then the problem is the drive voltages being produced by the DMR203.

If you swap the power cables from the VTX40 units to the motors, and the fault swaps tracks, then the problem is with one of the VTX40 units.

If you try all the above, and the fault is still with the right track then it's probably the motor/gearbox/running gear. If you leave the tracks in place and remove the motors, you should be able to test the track movement by hand and see if they seem to be as easy to move as each other. You can then also test the unloaded performance of the motors.

If you can measure the voltages between the blue/yellow drive cables for the motors when running at full speed, this should give a rough idea of whether they being driven at the same rate. You'll need to remove them, or elevate the tank first

Adrian.

[Marcel de Groene]

Hello Peter, Adrian,

Thanks for the solutions to narrow the problem down. Tomorrow I will have time to do this. I will let you know the outcome. I do hope its not a gearbox problem. I guess it will be very hard to get the motor out.

Marcel

[Adrian Harris]

Good luck Marcel.

The motors should only be three or four socket head bolts to remove. Easy enough with the right sized allen/hex key.

Support the motor as you loosen the screws, to prevent putting undue strain on the shafts etc.

And I would recommend wearing gloves, to protect your knuckles

Adrian.

[Marcel de Groene]

Problem solved. One of the speedcontrollers was toasted.

Thanks for all your helpful replies.

Regards,

Marcel

Panther is sold now and hopefully the new Owner will enjoy it as much as I did. If Armortek will bring a new StuGIII or Panzer II I might consider this as a new project. Once the Euro gets back its value.