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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#1
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Intermittent motor problem
I'm trying to fix a vacuum cleaner.
When switched on the motor fires for about half second on, half second off... The wiring all checks out so I'm left with the motor itself. Brushes all seem fine, plenty of life, strong springs and good contacts. What else should I check, and how do I check it? TIA -- Mike W |
#2
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Intermittent motor problem
"visionset" wrote in message ... I'm trying to fix a vacuum cleaner. When switched on the motor fires for about half second on, half second off... The wiring all checks out so I'm left with the motor itself. Brushes all seem fine, plenty of life, strong springs and good contacts. What else should I check, and how do I check it? I've now had it in more bits, cleaned the commutator to v. shiny, reassembled and no improvement. ??? -- Mike W |
#3
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Intermittent motor problem
On 28 Feb, 17:32, "visionset" wrote:
"visionset" wrote in message ... I'm trying to fix a vacuum cleaner. When switched on the motor fires for about half second on, half second off... The wiring all checks out so I'm left with the motor itself. Brushes all seem fine, plenty of life, strong springs and good contacts. What else should I check, and how do I check it? I've now had it in more bits, cleaned the commutator to v. shiny, reassembled and no improvement. ??? hopefully a multimeter will let you know where the o/c is. NT |
#4
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Intermittent motor problem
Sounds like an open circuit armature winding, you need a Mulitmeter across
it and turn it slowly by hand checking there is continuity reading between the brushes for each segment of the commutator. Sam Farrell "visionset" wrote in message ... I'm trying to fix a vacuum cleaner. When switched on the motor fires for about half second on, half second off... The wiring all checks out so I'm left with the motor itself. Brushes all seem fine, plenty of life, strong springs and good contacts. What else should I check, and how do I check it? TIA -- Mike W |
#5
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Intermittent motor problem
"Sam Farrell" wrote in message ... Sounds like an open circuit armature winding, you need a Mulitmeter across it and turn it slowly by hand checking there is continuity reading between the brushes for each segment of the commutator. Thanks Sam, I attached my mulit meter ;-) to both brush holders and turned motor (armature) very slowly. Readings were between 1.5 and 4.5ohms - no open circuits. Any other clues? -- Mike W |
#6
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Intermittent motor problem
On Mar 1, 8:33 am, "visionset" wrote:
"Sam Farrell" wrote in message ... Sounds like an open circuit armature winding, you need a Mulitmeter across it and turn it slowly by hand checking there is continuity reading between the brushes for each segment of the commutator. Thanks Sam, I attached my mulit meter ;-) to both brush holders and turned motor (armature) very slowly. Readings were between 1.5 and 4.5ohms - no open circuits. Clip an analogue multimeter to the brush holders and measure the voltage when it's running, taking due care to not electrocute yourself. I doubt that a digital meter will show a fast variation like that. If the voltage goes up and down then the problem must be in the wiring to the brush holders. Check that the armature isn't sliding backwards and forwards. |
#7
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Intermittent motor problem
"Matty F" wrote in message oups.com... On Mar 1, 8:33 am, "visionset" wrote: "Sam Farrell" wrote in message ... Sounds like an open circuit armature winding, you need a Mulitmeter across it and turn it slowly by hand checking there is continuity reading between the brushes for each segment of the commutator. Thanks Sam, I attached my mulit meter ;-) to both brush holders and turned motor (armature) very slowly. Readings were between 1.5 and 4.5ohms - no open circuits. Clip an analogue multimeter to the brush holders and measure the voltage when it's running, taking due care to not electrocute yourself. I doubt that a digital meter will show a fast variation like that. Okay I'll have to try it with my digital - it's all I have. But the stop start problem is ~1 second cycle so should be able to observe a change in reading. If the voltage goes up and down then the problem must be in the wiring to the brush holders. Can you explain why the conclusion - my electronics is a very rusty. -- Mike W |
#8
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Intermittent motor problem
On Mar 1, 10:59 am, "visionset" wrote:
"Matty F" wrote in message Clip an analogue multimeter to the brush holders and measure the voltage when it's running, taking due care to not electrocute yourself. I doubt that a digital meter will show a fast variation like that. Okay I'll have to try it with my digital - it's all I have. But the stop start problem is ~1 second cycle so should be able to observe a change in reading. If the voltage goes up and down then the problem must be in the wiring to the brush holders. Can you explain why the conclusion - my electronics is a very rusty. I assume that it's a 230v (thereabouts) AC vacuum cleaner, so there should be a continuous 230v AC at the brush holders when it's running. My cheap digital multimeter samples about once per second so that would be no good to see the problem. Maybe you could use a 230v light to check the voltage at the brush holders. But you need to be careful about electric shock so don't be touching anything when the power is on. Another possibility is that the commutator is not perfectly round. That would make the brushes jump up and down when the motor runs fast. Or (but unlikely) if the whole armature is sliding backwards or forwards in the end bearings when the motor is running. |
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