Engel TMAX experts - need help troubleshooting issue

[RCSubGuy]

Hokay, I'm stumpified.

I'm working on an Engel Typhoon with dual 750ml 6V piston tanks running off of the TMAX controller. I fired up the system for the first time today and the stern piston is working correctly. The forward one, however, is exhibiting exceptionally odd behavior:

• Upon power-up, it will cycle outward, but not back inward as they are supposed to do
• Commanding neutral buoyancy with K5 channel, it extends until it reaches proper extension with the sensor bar halfway (yay)
• It will not retract at all after that

I have checked the polarity of the motor. I have checked the wiring for correct ports. I have checked the sensor strip for proper seating on the control board.

Does anyone have any ideas regarding what the heck is going on?

[JHapprich]

Hall sensor itself is fried?

No PPM-mode supported by receiver? PCM wont work.

Low voltage enables the fail-safe. The voltage guard may not be set to the proper on-board current.

[RCSubGuy]

I'd entertain some of those ideas, but the other piston tank works perfectly. Viable that the sensor isn't working. Hmmm... I have a spare piston tank here, maybe I'll jump the leads to it and see if it works...

[Subculture]

If you're getting the correct status LED's lighting up on the board, then the likelihood is it's the relays or microswitches, which tend to be the most common cause of issues with these boards.

If I read your description right, the tank floods but doesn't empty.

Isolate the board from the tank connect to a bettery and a servo tester and command the board to empty, then with a volt meter, test between pin 1 positive and pin 3 negative. If you get an output there then the fault is most likely with the wiring and/or microswitches on the tank.

If no feed, then you need to check whether you're losing your positive or negative feed.

1. Test pin 1 positive to battery ground on the board. If you get a feed then goto test 2. No feed suggests an issue with your positive (high side) relay contacts.

2. Test pin 3 negative to battery positive. No feed there will suggest an issue with your negative (low side) relay contacts.

[Subculture]

Saw your video showing the yellow light indications, which suggests to me that the control circuitry is fine, and that the problem is with the relays or tank microswitches, with the relays being the most likely candidate.

[trout]

I would lean to micro switch. If you switch pistons you can eliminate part of the issue if it does not follow the bad one.

[Subculture]

Substitution is a viable test, but in the time it takes to loosen just one of the terminals he can do the checks I suggest and it will at least confirm whether the issue is with the board or the tank.

[trout]

Agree. I have good feeling Bob’s got this.