Panther Speed controllers question

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Lawrence Godson
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Panther Speed controllers question

Post by Lawrence Godson » Thu Jan 23, 2014 1:55 am

I have a first generation Panther with two Q4D VTX 40-24 speed controllers. A few months ago I experienced a malfunction whereby the left track would refuse to run. Upon recharging the batteries the problem seemed to resolve itself. Recently however it has returned and for a while tapping on the left track speed controller would result in the track working again. Eventually the symptoms got to the point where constant tapping was necessary and the running was very erratic. It would run until shut down and then require one or several taps to get going again.

Finally it refused to run at all. Mark felt that it was most likely one of the relays which are 2 small square black boxes sitting next to one another in the speed controller housing just next to an aluminum heat sink. Mark feels that the relays are "standard" components but does not know the make or model because he does not use them any more and there are no markings on the visible 5 sides.

Before I attempt to unsolder them and see if I can find replacements - has anyone else had this issue and what was the actual culprit? Did anyone experience a similar problem that turned out to be some other component in the speed controller? Does anyone know where I might be able to purchase the relays?

I did remove the board and examine it carefully with a strong light and magnifying glass but could find no breaks in the circuits or solder joints. I also checked the four main connecting wires to be sure that they were solid connections. Any help/suggestions would be greatly appreciated!

Lawrence Godson

Maarten Schutjes
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Re: Panther Speed controllers question

Post by Maarten Schutjes » Thu Jan 23, 2014 7:36 am

Perhaps ask 4QD?

And You can still buy new ones at 4QD.
Interested in animatronics for your tank? Contact me at | See examples at

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Adrian Harris
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Re: Panther Speed controllers question

Post by Adrian Harris » Thu Jan 23, 2014 8:36 am

4QD provide quite a surprising amount of information about their controllers, and servicing them:

They also don't seem to averse to people undertaking DIY repairs:

Given your location, and the cost of returning a controller, they may be able to assist with the relay part number.

I use Farnell to purchase a lot of my components. The US site is here:

If the specific parts you require are only available in the UK, I'd be happy to order them for you and forward them on.

Contact me at for details of my smoker fan control module and other electronic gadgetry

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Re: Panther Speed controllers question

Post by leesellars » Thu Jan 23, 2014 7:30 pm

Hello Lawrence

I have a brand new set if you are intersted.

Dont hit me so early in the morning with those negative waves.
Listen carefully i shall say this only once.
If its not broke dont fix it.
Ich Hatt Einen Kameraden

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Robert E Morey
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Re: Panther Speed controllers question

Post by Robert E Morey » Fri Jan 24, 2014 5:18 am

I had a problem with my Panther back when I first installed the speed controllers. One of the 4QD was apparently defective. On one side the track would only go in reverse. The other side worked well both forward and reverse. I had a Sherman which used the same 4QD controllers. I replaced the Panther speed controller with those from Sherman and the Panther tracks worked fine.

Gill replaced the defective unit and it has worked fine ever since. It could be a relay issue as well. They will be cheaper to replace than the 4QD.
Best regards,

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