Trouble during start up

Submitted by Devil p on Fri, 12/01/2023 - 15:04

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I recharged the batteries and when I put them back on and switch on the Monsterborg the lights start flickering through all colors. (No WLAN connection) I suspected a voltage or connection problem but can not find a solution ???
The battery level is at 12V and the connection seems to be o.k.
Any advice where to look and what to try.

Devil p

Sat, 12/02/2023 - 17:19

I found this:
http://forum.piborg.org/node/2727
and checked the voltages .. there is nothing on either pin.
Does this probably mean it is the LED again (see http://forum.piborg.org/node/2943)?

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piborg

Mon, 12/04/2023 - 12:16

These are rather odd results, they appear to be contradictory...

No power on the measured pins suggests the power from the battery is not making it to the 5V regulator. This means the regulator cannot power the 5V pin and nothing on the ThunderBorg or Raspberry Pi would be powered, so no LEDs should be able to turn on at all.

On the other hand the LEDs turning on would imply the regulator is powering the 5V line enabling them to turn on. If they are going through a red-green-blue sequence repeatedly that would suggest the ThunderBorg's logic chip is restarting repeatedly as well.

Since the logic chip restarts when the 5V line dips too low and the apparent contradiction I think it is probably a bad connection somewhere, likely between the battery and the 5V regulator. Possibly a bad solder joint or a faulty power switch.

I have attached an image of where the battery 12V path should be all the way from the pack to the regulator. The first thing is to check the connections at each point and see how far the 12V is getting.

Images: 

Devil p

Mon, 12/04/2023 - 13:25

Thanx piborg for reply!
The connections show the following:
(from lower part to upper part of your picture)
the 3 on the lower end of the picture are o.k.
the one next to the capacitor is dead
the one on the switch is o.k.
the remaining two are dead

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piborg

Mon, 12/04/2023 - 18:32

The one next to the capacitor is the connection between the two PCBs, so the main PCB is not getting any power.

Did you check both sides of the switch? If 12V is only on one side with the switch on then the switch is the problem.

Devil p

Tue, 12/05/2023 - 09:10

you are right: it seems to be a switch problem, at least I could get it into a state where I got the %V and 12V on all the positions correctly. Looks like it is stable, but i'm not sure ?
Any suggestion ? where could I get a replacement switch ?
Thanks a lot !!!

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piborg

Tue, 12/05/2023 - 10:37

The part number for the switch is JSA4-1-G0. Most of the big electronics resellers have them, but you might be able to get one cheaper on eBay.

Here is a Farnell link for them: https://uk.farnell.com/erg-components/jsa4-1-g0/switch-jumper-1-way-spst...

Devil p

Tue, 12/05/2023 - 13:43

Thanks for the information: the cheapest I could find so far is 10€ (w shipment) would be easier and cheaper I would need 10K of those :-))
Thanx again for all time support !!

Devil p

Sun, 02/11/2024 - 12:48

Sorry Piborg getting back that late (had some other projects in the meantime)
I checked all the voltages on the board and they looked o.k. but the voltage still breaks when I try to start the motors.
I got a new replacement board in the meantime but it shows the same problem: as soon as I try to run the motors the voltage gets low, the lights change colors, the WLAN connection breaks, the low voltage sign comes up, it doesn't seem to be the board ???.
I checked the Rpi and it seems to be o.k.
Getting a bit desperate!
After reading again the previous notes and some further testing:
sometimes it does not even start the Rpi, running the LED cycle as you mentioned
sometimes it is able to start the RPi but latest when I try to run the motors the voltage
gets low
I'm pretty much convinced now it is not the switch, with the old and the new board
I get the same performance.

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piborg

Mon, 02/12/2024 - 17:26

At this point I think the problem is either a faulty battery or faulty motor. In both cases this would cause the power to drop out when trying to start the motors.

Since you seem to be seeing problems even starting the Pi occasionally, it is more likely that the problem is a faulty battery (possibly more than one). We have had that happen a few times when we were running Formula Pi, occasionally one of the MonsterBorgs would not run properly but swapping the battery pack out for another set fixed it. Each time we would find that a battery in the pack was not holding charge properly when we checked them the next day.

If it is a failed battery then replacing it will fix the issue. The tricky part is figuring out which battery is the problem. You can try measuring each one with a multimeter and see if one is noticeably lower voltage than the others when charged. This doesn't always find a bad battery, but it is a quick way of checking them.

The faulty battery will discharge much quicker than the others, so if you have anything that can run off 1 or 2 batteries that drains them reasonably quickly you can try each in turn and see if any run flat quicker than the others. Some chargers have a test or discharge mode that can do this check. This can take a while, especially if all the batteries turn out to be fine.

Alternatively if you have another set of batteries you can try replacing all of them and see if the problem goes away. If it does you can try swapping a single suspect battery into the pack at a time until you find the ones which cause an issue.

Devil p

Tue, 02/13/2024 - 09:14

...this sounds very reasonable !! After I had changed the battery set, I got it working again and could run the motors. Now I have to find the faulty battery (and think about what I can do with the second board :-))) ).
Thanks a lot, your help is always very much appreciated !!!

Devil p

Mon, 02/19/2024 - 16:42

..sorry I have to come back once more ... the results don't look very conclusive ?! (sometimes the change of batteries helps, sometimes it works with the same battery set?!)
Is there an easy way to test the motors ?

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piborg

Tue, 02/20/2024 - 13:14

Generally speaking motor faults don't tend to be intermittent, so it probably is a battery issue still.

Faults that can occur:

  1. Shorted coil
    In this case the motor won't work at all and will consume more power than normal.
  2. Partly shorted coil (unusual)
    In this case the motor will run slowly compared to normal and may get hotter than normal. Should be very different compared to the other motors when running at a fixed power.
  3. Broken power wire
    In this case the motor won't work at all and would read as open circuit with a multimeter. This wouldn't cause your problem since it is the same as the motor being disconnected.
  4. Damaged gear
    This will prevent the motor running smoothly and in the worst case will cause it to jam up. You can feel for this by slowly and gently rotating the motor by hand via the attached wheel for several rotations. If it feels crunchy or has a spot that is harder to move past

Devil p

Tue, 02/20/2024 - 15:13

I ordered a new set of batteries ... will see ??!!
Thanks for fast reply

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