Battery operated power drill chuck rotation opposite of intened direction

[videobruce]

This is a good one, especially since it involves the drill changing directions from one day to the next. (The motor assembly was changed out previously)

Long story short:
Bosch hand held drill chuck rotation was reverse what it should be. I opened the enclosure and reversed the motor leads and all was fine. I used it a number of times that same day. The very next day when I checked to confirm all was ok, it reverted back to opposite rotation by itself. Forward was reverse, etc.

There are two transistors (3 leg) attached to the heat sink in the base of the handle and one other component (2 pin), rectangular in shape. My guess is it's a capacitor, but I never saw one like that before, the corners were not rounded. If there are any other components, they would be in the trigger switch itself.

Ok, would someone like ti explain WTF is going on? I haven't tried to re-reverse the motor leads again yet.

[SeanB]

You have a reversing switch and are randomly operating it. only real explanation, most electric drill now do have them.

[videobruce]

The switch is not "randomly" being operated. I have used enough hand held tools to know how to operate them especially drills and more especially since I have a 2nd exact same model.

[David_AVD]

Are you the only one with access to the drill?  ie  Could someone be messing with your sanity?

[xavier60]

Usually with battery powered drills that have a brushed motor, any electronics in the drill are for PWM speed control only, not for reversing polarity to the motor. I wonder if there is something loose or slipping inside of the reversing switch causing it to sometimes reverse its action.

[videobruce]

Yes, I'm the only one that uses it.
The reverse switch is solid, no glitches, dead spots etc. It was suggested elsewhere that there is a microprocessor somewhere. If so, I'd like to know where it is. Like I said, I only see 3 components at the base of the handle just above where the battery pack is and nothing else.

See this link;
https://www.boschtoolsservice.com/Order/IPL/IPLDetails.aspx?tn=3601H66110&mn=DDS181-02&RelatedTools=3601H66110;%203601H66111;&init=1

I contacted their support. The support guy I talked to says there is a microprocessor in or attached to the trigger switch. He didn't know what this large retangular component was. He had no idea why it did what it did either and will pass it up the chain.

In the mean time, I will re-open it back up, swap leads again and see what happens (without closing it up again).

[StillTrying]

Brushes moving/rotating around a bit?

https://www.toomanytools.com/moteur-bosch/2000-bosch-moteur-a-courant-continu-18v-2609199359.html

[videobruce]

Are you referring to 'slop'?

Ok, there apparently is, or probably is a microprocessor, it's in a sealed (epoxy) circuit board at the very base just above the plate that holds the battery. I didn't notice it before, but I did now. It's surely isn't in the trigger. I swapped the leads, it runs correction for now.

That mystery part on the heat sink # is 2109771077, but a search only turned up phone numbers.

[AF6LJ]

I remember this discussion...

[videobruce]

Details?

Bosch did get back to me and suggested the 'plate' that has the brushes a possible problem. I have examined it and see or feel no exception. They told me to let them know of any developments which was refreshing for a change..

[AF6LJ]

This was discussed yesterday over here...
http://www.eham.net/ehamforum/smf/index.php/topic,116942.msg1023776.html#msg1023776

[videobruce]

With no resolve either.

[StillTrying]

You can get a close up view of the brushes on here, and here. But I don't know anything more about this type of DC motor. (or any other type come to think of it!)

http://www.elektroserw.pl/product-pl-2770-Bosch-silnik-do-wkretarki-2609199359-GSR-18V-LI.html
http://ctn.home.pl/pl/p/Silnik-wkretarki-Bosch-GSR-18-V-LI-.-GSB-18-V-LI-.-GSR-18-V-LI-HX-2/1391

[xavier60]

My Makita charger went from making beeping sounds to playing tunes because by chance I did a series of actions that changed a setting.
I wonder if there is a sequence of actions that will toggle the action of the direction switch on the Bosch drill.

[Cyberdragon]

A DC motor requires an H-bridge to reverse, which is not possible with only 2 transistors. It's either in the motor or the gearing.

[Nusa]

If the reverse switch works, wouldn't simply changing that switch be a lot easier than swapping the motor leads? I know it doesn't explain the phenomenon, but it's eminently more practical than opening it up every time it goes the wrong way.

[AF6LJ]

With no resolve either.

Truthfully; I wouldn't worry about it, just use the drill.

[videobruce]

I did open it up again and swapped leads. Checked it twice afterwards before I buttoned it back up. Did so today, re-assembled it and used it. So far so good. If it happens again, yes I will just use it as remembering that the directions are reversed. 

[Cyberdragon]

I might be talking nonsense but is it ok to run a DC motor going in the wrong direction for the given polarity? (if it is the motor at fault)

[AF6LJ]

I might be talking nonsense but is it ok to run a DC motor going in the wrong direction for the given polarity? (if it is the motor at fault)

It won't hurt the motor to run it en ether direction.

[Theobald]

Following Cyberdragon: is it possible for a DC motor to start in the wrong way ?
Interesting question, because the mechanical design is symetrical, if you want to make it turn in the both directions. I guess brushes vs magnets position is crucial.


Any DC motor specialist on duty ?

Theo

[David_AVD]

Measuring the voltage polarity applied to the motor in the "normal" and "wacky" states would clear up whether it's the motor (unlikely) or electronics playing up.

[Cyberdragon]

Measuring the voltage polarity applied to the motor in the "normal" and "wacky" states would clear up whether it's the motor (unlikely) or electronics playing up.

The electronics can't change the polarity with only two transistors unless they have three rails, plus, minus, and 0V. It might also be some oddity with the snubber causing a reverse pulse that starts it in the wrong direction.

[David_AVD]

OK then, how about "Measuring the voltage polarity applied to the motor in the "normal" and "wacky" states would clear up whether it's the motor (unlikely) or switch (including whatever circuitry) playing up."