Genie TMZ 50 stuck in down only mode

[DaveP52462]

Hi,
Working on a TMZ 50. Its spitting out a code 0003-- "Down only mode"... We have checked continuity on the out rigger switches back to the control board. It checks out fine. The bubble level is reading 2.5V on the X and Y-axis. It is stuck in "down only mode". The service manual breaks it down to a leveling issue. The outriggers switches function as they should. The bubble level is output is 2.5V on either axis as should be the the turn table switch, the main boom and the platform switch which are in series function as expected. We can level the base manually but we still do not get any upward movement at all. All down functions work fine. Last year we got alarm beeps while in the air, It came down fine and we never again got any upward movement..

 

[VoodooMojo]

not sure where you got the voltage readings for the level sensors from but they should be taken at pins 34 and 35 of the lift/drive connector located at the bottom of the ground control box.

also verify that the outrigger switches are checked by taking voltage readings at pins 18, 6, 29, 17, 20, 8, 30, and 19 at the outrigger connector located at the bottom of the ground control box. The voltages on these pins must all be within a volt of each other when the outriggers are deployed. If any of the terminals have no voltage on them then there is an open in the circuit somewhere.

 

[DaveP52462]

Thanks for the quick reply...

The voltage for the bubble sensor was first taken at the sensor wires by pricking into it then verified at the connector. Getting about 2.5v on both axis when leveled using the bubble.
We have no voltage on any of the pins relating to the outrigger switches on both sides of the switch. What voltage should I see? 5v...12v? I'm assuming the voltage is fed from the controller side and then passes thru the switch and monitored by the logic circuits. Is the feed voltage to the outrigger from a common bus? relay? I have the box out of the machine on the bench testing with a 12v power source. We have the lift control box hooked up to it. We did check all the pins you mentioned while installed on the lift also at the connector. We did not see any feed voltage to the switches. The switches do function continuity wise.. Looks to be a fried board? I will take the board out of the case and see if I see any burnt traces on the bottom side of the board. we only have a few hours of work to finish our project and wonder if I can feed in external feed voltage to the switches to get it to go up to fish the job for now.. Also, do they repair my board or do they just replaced the board when I send it in for repair? Where can I get the board repaired and how much. Thank you in advance for any help you can provide me...

Dave..

 

[VoodooMojo]

Dave, what is the serial number of this unit and any other info you can provide.
DC only, Gas or Diesel only, etc..
thanks

 

[DaveP52462]

Ser:T5003-228
2003
Gas model

I'm following schematic from page 6-18, 19 from the service manual.
I took the board out of the case and got some more info.
Traced one side of the circuit, Pins 6,8, 29 and 30 go to U4 and U6 pins 1 and 4.
This chip is a MCT62 which is a 2-ch opto isolator. Anode side so it is expecting a positive voltage.
The other 4 pins are the bus feed which are all connected together. Pins 17, 18, 19 and 20.
I traced the lines they go to a via that does not seem to have a connection from top to bottom.
Seems that the connection is open from the top to bottom of the board.
It seems that it should be feed 12v and is not seeing it.
I can solder a jumper wire and things should be fine.
Does this sound right to you.

 

[VoodooMojo]

As a representative of the manufacturer I cannot agree that doing as you suggest will facilitate a repair.
I can say as a test procedure that it makes perfect sense.

 

[DaveP52462]

Thanks for you help. You led us down the right path.
We found that the feed voltage trace was open at the via from top to bottom of the PCB.
We soldered a wire and all is well.
We will send the board in for repair after this job is done.
Thanks Again and have a great day.