Boom Crane

Given the potential liability issues should the crane become the leading agent in an accident that involves damage to property, injury or death, contacting the manufacturer immediately for a service call-out is the only sensible way to go, and may even be a requirement for insurance indemnity cover on the crane.

• Prohibit the use of the crane until the manufacturer's appointed local service agents have carried out the repair, and there is a document from them saying that this repair has been completed and tested to be working correctly.

Hi Guest

Not withstanding PW's reply which is absolutly correct, try looking for a 'wire pull transducer' usually threaded up the inside of the boom. If the wire has become dirty or the 'snubbing gromit' that allows the wire to return to the drum is grooved, the transducer will give erratic readings (or if the wire has broken, a static reading). This is a relatively cheap component and should not be ignored on cost grounds.

Good luck with it!

Ok, just to satisfy your curiosity:

1.-Try retracting the boom completely and measure the voltage across the pot (ends only, not wiper).

2.-Disengage the pot mechanically from the boom, find the negative side of the pot and measure the wiper against it, as you turn it fully ccw and then cw.

3.- You should read from 0% to 100% of the voltage across the pot ends. (keep an eye on the crane's display).

4a.-If the voltage increases smoothly and you have a proportional readout on the crane's display from Min. to Max. lenght, then you have a problem with the mechanical linkage to the pot.

4b.-If you have "bumpy" voltage readouts, then you have a bad pot.

4c.-If you have smooth voltage changes as you rotate the pot, but your cranes's display shows erratic measured lenghts, then the module receiving the signal has a problem.

Once you isolate the problem, have a certified service contractor to fix it. (You don't want liability issues).

Let us know how you finally got it up and running.

Yahlasit

hi,

i did test the voltage received on the module, its changing as the potentiomater turning, but there is no change on the display readings. when i turn the potentiometer and it reach some point, the display show dashes and alarm is on. when i turn the potentiometer opposite way, the display shows back the 12.1 meters, the lenght of the boom.

in other words, the display shows either 12.1 or dashes! no thing else!

It sounds to me like a saturated ADC (analog to digital converter), if you are willing to troubleshoot it yourself (which I don't advise) take out the board, identify the signal input components and gunshoot 'em all (replace them all without detailed testing), this is also called "the bulldozer technique". Just make sure you don't replace any programmable chips, (unless you have new blank chips, the software + the hardawre to "burn them" and the source code).

BUT before you embark on this adventure, why don't you call a friendly competitor? ask him to lend you the module, or have a service company to replace it as a "diagnostic" procedure. And if it is the culprit, buy a new one.

Keep us informed

Yahlasit

Test if at fully redrawn boom your screen shows the right length. If yes it's pre A/D input cirquitry (probably an op amp) gain problem. There must be pots to adjust. If not it's pre A/D input cirquitry biasing problem. There should be pots for this also. If there aren't pots meaning calibration is done digitally just forget the project and seak manufacturer help. Any changes/servicing done recently on the crane? (e.g boom pot changing etc)