LFEP problem with motor

[palo974]

Hello,
Yesterday I tested the last update. The clouds wasn't there since a wide.
Usualy, I used to going at 100X for the goto with my CG5 original motors but now i need to fix them donw to 50X.
At 100X, my motor don't work at all, at 50X they work good but it too slow. Between these values motors don't run aconstatilly.
even if the 40V delevery is on.
I didn't change any courants values for the motors.

Did I need to change something?

CS
Patrice

Hi Patrice,

Did I need to change something?

Issues related to motor speed are obviously not related to the ASCOM driver in use: you will find the same speed limitation also by using previous releases or by moving the mount by hardware handbox.
Maybe you're using a too low current value for your motor or your battery is not properly charged (if you're using a battery to power your LFEP).
Keep in mind a too low voltage will make V40 board not working: some days ago I started to think my V40 was faulty (I can hear a louder motor noise while V40 is enabled). Then I realized the battery voltage was well under 12V... 
You can also try to set an higher ramp value, if available.
Another cause of the speed issue could be a low temperature so that an higher load torque is required (e.g. because of bad grease or too small worm-worm wheel play).

Clear Skies!
Armando

Hi Armando,
Thanks for your reply. I move to a nex topic.
Yes I have the same behavour with the ASCOM and the hadbox.
It wasn't a problem of main power because I used a 15V laptop power.
I tried different value for the ramp between 10 to 150 but nothing was good.
For the temperature, actually I've got at least 16°C at the morning at 25 m above the sealevel.
We need to go at 2200m to expect to have arond 10°C at night (Réunion island).
And I changed the grease.
I tried value between 600/1200 for the motor.
How can I check the output value. I don't think voltmeter is good for that?
Maybe this is the 40V board because It was the speed of 50X I had before this option.

Thanks for your help because I lost in electronics.

CS
Patrice

[Armando]

Hi Patrice,

It wasn't a problem of main power because I used a 15V laptop power.

Ok, first of all check the output voltage... 
If there is still the need to check V40 board then a voltmeter is enough to check 40V inside the LFEP... 
But frankly I think you can simply hear noise coming from RA motor: you should find tracking noise (with no need to send any GoTo command) really louder as soon as you enable V40...

If you were able to move at 100x only with ramp enabled, then keep in mind that ramp starts at backlash speed. Maybe now backlash speed is too high and makes ramp not useful...

CS
Armando

[Armando]

Another reason of the issue could be related to speed ramp: some motors are affected by small pull-out torque values around some frequencies.
Setting Goto speed fixed at 100x and playing with ramp_value and starting_ramp_speed (backlash speed) maybe you make the motor not working at these bad frequencies...

CS
Armando

[the_lizardking]

Hello Patrice,

when it works with 50x and you tried to change the ramp settings as well as the current or you really did not change anything on the old setting and you cant hear the motor stucking,... you have an absolut unusual problem.

You can try to check with voltmeter and if you have power there check the movements when motors are stripped down. But turn the tracking off - so there should noit be any power when doing nothing and really take out the motors completely. Try one after the other, first voltmeter and then take out the motors.

cheers

[palo974]

Thank for your reply.
I try to change value of the setting but It was unsuccessfull

During my tests, I finally had a problem more seriously.
I had a funny smell which is not good just before LFEP is reset.
So I opened the box and outlet plates to visually check the condition of the circuits.
I found a component that overheats and bears signs of this heating.
I enclose you a picture that I have identified the component in question.

Could you tell me what it does and if I can change to solve my problem?

thank you for your help.
Patrice

[Armando]

Hi Patrice,

Could you tell me what it does and if I can change to solve my problem?

L6258EX, it's the RA or Dec motor driver. 
It should disable its outputs if temperature exceeds the safe limits. But if you see signs of failure... 

CS
Armando

[palo974]

Armando thank you for your reply.

I worried that I'll need to change this component because I can see cracks on it.
Do you think that it's possible?
I hope the rest is correct.

Thank you very much for your help.

Patrice

[Armando]

Hi Patrice,

I worried that I'll need to change this component because I can see cracks on it.
Do you think that it's possible?

Heat dissipation is critical. This is the reason why PowerSO-36 package makes use of via holes.
As there is no need to take care of the broken IC, removing it should be not so critical; cutting the pins could be of help...
As the IC slug is soldered on the via holes, heating them from the opposite PCB side should make removing the IC possible... Then the PCB should be properly cleaned.
But I think that soldering the replacement IC by hand is really difficult: pins are too thin; I would suggest a soldering lab to exclude possible mistakes. 
I never attempted to solder any SMD IC. But online you can see some DIY guys are really able to make "everything"  with no need of the specific/required tools...
Anyway a lab is surely able to replace the IC.
 
Armando