Bosch 1199 VSR Hammerdrill - quit

Discussion in 'Tools' started by Sparky617, Jun 15, 2018.

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  1. Jun 15, 2018 #1

    Sparky617

    Sparky617

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  2. Jun 15, 2018 #2

    Sparky617

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    According to the website I linked above the brushes are the most likely cause followed by the switch.
     
  3. Jun 15, 2018 #3

    nealtw

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    Check the condition of the spring and the connection to the brushes, usually you can see the problem
     
  4. Jun 15, 2018 #4

    Snoonyb

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  5. Jun 16, 2018 #5

    joecaption

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    Brushes sticking in the holders, worn brushes, dirty commentator, trash between the segments in the commentator, bad cord.
    Dead segment in the commentator.
    Unless the brushes are so worn there not making contact with the commentator that's not the issue.
    Brush holder, simple to check, slide the brush up and down, sticking, remove the brush and blow it out with air.
    Amature glazed wipe it down with sandpaper.
    Clean up between the segments on the armature with flat bladed jewers screwdriver.
    Dead segments in the armature can be checked with a volt ohm meter set on ohms between the segments.
     
  6. Jun 18, 2018 #6

    Sparky617

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    I have power through the switch and to the contacts on the brushes. I'm not a contractor so over the 7 or 8 years I've owned this it hasn't gotten the use a contractor would give it in a couple of months.

    The brushes look OK and are making contact. I need to dig into a bit more with my VOM to check for continuity. It was working ok before it stopped, no excessive sparking or problems with not starting. When I went to use it last weekend it was like it wasn't even plugged in, not a twitch, nothing. I did blow it out with compressed air. I'll pull the commutator out and see it looks like.
     
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  7. Oct 26, 2019 #7

    pjones

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    Did you ever find the problem?
     
  8. Oct 27, 2019 #8

    Michael Armstrong

    Michael Armstrong

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    I rescued one of those from a dumpster outside the company shop about 25 years ago. Same symptoms, an old tool, so they just trashed it. Turned out the power cord had an internal (and intermittent) break right at the strain relief. I just pulled about 8" of cord through the strain relief, cut off the bad segment, and reconnected at the good end of the cord. Time to fix, about 1/2 hour. Cost, $0.00.
     
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  9. Oct 28, 2019 #9

    Sparky617

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    Nope, I was looking at it last week and I have continuity from the plug to the commentator when I pull the trigger. I wound up buying a new one, because I needed one right away for a project I was working on and didn't have time to play around with this one. The neutral has continuity through as far as I can test.

    I'd love to fix it, and I haven't given up.
     
  10. Oct 29, 2019 #10

    pjones

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    Did you confirm the brushes move smoothly in the brush holder? They can be prone to dust causing them to jam up.
     
  11. Oct 29, 2019 #11

    Sparky617

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    Yes, they slide easily. The inside of the tool is pretty clean. It really feels like there is an open because it doesn't twitch or do anything when you pull the trigger, though I have power to the armature. I guess it could be an open neutral, but I have continuity into the connections to the motor.
     
  12. Oct 29, 2019 #12

    pjones

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    Is there a thermal fuse you can check for continuity?
     
  13. Oct 31, 2019 #13

    Sparky617

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    None that are easily accessible, so I think probably not. I have continuity from the plug, through the switch to the contacts on commutator. I'd think if I had a dead segment on the commutator that when I move it around I'd get some kind of response out of it.
     
  14. Nov 1, 2019 #14

    tmiskimen

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    You described the drill as variable speed (VSR). There is some electronic circuitry in there then that controls the speed. If you are careful and are fairly knowledgeable of electric circuitry you can jumper out or bypass the electronics and see if it runs then (doing this will make it run at high speed, so be prepared).
     
  15. Nov 1, 2019 #15

    Michael Armstrong

    Michael Armstrong

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    Yeah. If you've got 120VAC at the commutator, it ought to work. I'm stumped too, if that's any consolation.
     
  16. Nov 1, 2019 #16

    Michael Armstrong

    Michael Armstrong

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    The more I think about it, 120VAC at the commutator doesn't make much sense in this variable-speed, reversible device. This thing has a very fancy trigger assembly (with a reversing switch), that I suspect converts AC to variable DC to drive the motor, control the speed, and reverse it. I can't find any Theory of Ops - kind of documentation anywhere, but I'll bet this switch has gone TU. They're about $40, readily available, and worth a shot.
     
  17. Nov 1, 2019 #17

    Sparky617

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    Check out the diagram and parts list here: https://www.ereplacementparts.com/b...rque-hammer-drill-parts-c-128_1032_14808.html
    There is nothing in there to convert it from AC to DC.

    The switch (part 804 on the diagram $39) is 120v.
    You change the direction of the drill by rotating the brush holder assembly (part 76 on the diagram $16). Checking with my VOM the voltage changes as you pull the trigger.
    I pulled it apart and used 400 grit sandpaper to clean the armature contacts (part 3 on the diagram $35). Still nothing.
    It really feels like an open on the neutral to the field (part 2 $14)

    At the price of parts, you can quickly pay more in parts that it costs to replace the whole thing. If I feel motivated again, I'll try pulling it apart again and removing the field coil. To see if I can test it.
     
  18. Nov 2, 2019 #18

    Sparky617

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    The trigger switch has a variable resistor that controls the speed, there aren't any electronics in it to convert the AC power to DC, just a simple variable resistor that my VOM says is OK. When I test it with my VOM the voltage changes as you squeeze the trigger it moves from 0vac and goes up to 120vac at the brushes. Bypassing the switch won't prove anything since I'm getting voltage out of it to the commutator.

    I really think the only thing left is the neutral wire to the field coil. Though this thing hasn't really been abused since I'm not a pro using it all the time. The brushes move freely, I get power from them to the contacts on the armature. Since I've already bought a new hammer drill, I'm not inclined to buy a bunch of parts to try to fix it as it wouldn't take many parts to equal the cost of a new drill, which I already have. At this point, it is just the challenge of trying to figure out what the heck is wrong without spending any money on it that keeps me from just chucking it in the bin. It certainly isn't worth taking it to a tool repair shop, if they even exist anymore to try to get it fixed. It was probably $100 new, the replacement I bought was around $100 and the parts I listed above would get me to $100 pretty quickly. These tools really have become disposable.

    Anyway, thanks for the suggestions.
     
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  19. Nov 2, 2019 #19

    pjones

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    Have you checked for continuity in the neutral from the plug to the motor?
     
  20. Nov 2, 2019 #20

    Sparky617

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    As far as I can, yes. That would be to the point where the jumper goes from the switch body into the case for the connection to the field winding.
     

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