Heng Long M26 turret rotation (or not)

[Spam In A Can 26]

OK, next Heng Long M26 Pershing (Snow Leopard) issue.
Turret doesn't rotate. It used to work then I accidentally over rotated it & after clicking twice it was stuck in the 5 o’clock position.
Ring gear is free, 2 separate turret turning motor/gearboxes will turn the motor & the turret if I jump 7.2 DCV into the motor leads.
With motor/gears disconnected I manually rotated the turret back to dead ahead, just in case, but it still doesn't work. VOM says no voltage at motor terminals when left/right transmitter lever is pushed, but I do get a turret motor sound effect. To my mind that eliminates the transmitter as a problem, so what is messed up seems to be in the tank itself.
I'm going to start tracking the wiring back step by step through upper hull connector & connector to MFU socket next.
Anyone have any bright ideas for me?

[PainlessWolf]

Good afternoon,
HL gear rotation motors are cheap as chips. Ask on the board here if someone has an extra they can spare or go to ForgeBear's website and see if he can be of assistance. If you are in the States, Spam, use Taigen Tanks\IMEX in Florida. Again, cheap and cheerful.
regards,
Painless

[Spam In A Can 26]

Why am I replacing the motor when I have 2 that are working?
When I give them voltage they both work. My problem is not getting voltage to the motor.
I don't understand.

[RobW]

Do you get power from the board when using the rotation? I'd start there if the motors are OK.

[PainlessWolf]

Spam,
"No voltage at motor terminals" is what sent me down that path. When you hit the stick on the TX, do you see the little gear on the rotation assembly turn? Or just hear the motor whine?
regards,
Painless

[Spam In A Can 26]

Neither.
All I hear is the sound effect for the turret turning.
The motors (& gears) both turn normally If I apply voltage to the motor terminals.

[AlwynTurner]

Hi Spam, it sounds obvious I know but have you checked for loose/bad connections working from the board through the upper hull connector into the turret? It might be worth checking for voltage at each connection point. It could be that there is a bad solder to one of the connectors.
Alwyn

[AlwynTurner]

Hi, you will probably find it useful to have a standard Heng Long wiring diagram and I have used this in the past


Hope it helps
Alwyn

[Spam In A Can 26]

Hi Spam, it sounds obvious I know but have you checked for loose/bad connections working from the board through the upper hull connector into the turret? It might be worth checking for voltage at each connection point. It could be that there is a bad solder to one of the connectors.
Alwyn

That's the next step going over everything with a meter to see what I can discover.
I don't understand how it would suddenly no longer work though. Maybe it tugged on the wiring when it over rotated?
When I work it out I'll report to save the next poor devil this frustration!

[AlwynTurner]

Hi Spam I think you have hit the nail on the head. When it over-rotated it probably did something to the wiring so I think that should be your starting point. Use the circuit diagram and a meter and see where the circuit fails

Alwyn