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Karcher Motor Start Problem


 
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BrianKeith

from United Kingdom

Joined: 18 Mar 2009
Posts: 6
Location: Kent,
United Kingdom

PostPosted: Wed Jun 10, 2009 11:44 am Reply with quote

I have a Karcher K620 MH high pressure washer which won't start. The green pilot light on the on / off switch is illuminated when connected to the mains, so I assume there is power to the unit. I have carefully stripped it down and other than the motor being knackered, I can only assume it is the capacitor or on / off switch. I am not an electrican, but have a multimeter. Does anyone know what I should set the dial to to test the circuit on the capacitor please. Also, does anyone know how to test the switch circuit please. I would also appreciate any other clues as to what the problem may be.
Thanks very much.
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Spark123

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PostPosted: Wed Jun 10, 2009 5:41 pm Reply with quote

Unless your meter measures capacitance - it could be denoted by a schematic pic of a capacitor then you can't measure capacitance with it.
Can you upload a photo of the multimeter and a photo of the motor? Does the motor have brushes?
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jj4091

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PostPosted: Wed Jun 10, 2009 6:20 pm Reply with quote

Karcher capacitors failing, is quite common http://www.cleanstuff.co.uk/acatalog/Karcher_K695_Spares.html before you order though also check that the input filter & your hose pipe are completely free from obstruction. If you are competant to work on live equipment then you should measure the same voltage from each side of the capacitor to neutral. Please do not try this unless you are 100% sure it is safe.
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BS3036

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PostPosted: Wed Jun 10, 2009 6:23 pm Reply with quote

On mine it was always the switch. It's easy to check that if you can access the switch contacts (unit unplugged of course) and set meter to Ohms and connect across switch contacts. Operating the switch should change the reading from almost 0 Ohms to something higher or different anyway depending on the meter.
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Taylortwocities

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PostPosted: Wed Jun 10, 2009 10:44 pm Reply with quote

If you have an analogue meter wou can basically test the cap using the ohms range. Connect the meter across the cap and you should get no reading, reverse the leads and you should get a blip on the scale as the cap discharges. The reading should then settle back to zero.

Never tried this with a digital meter though..... Worked great with the old AVOs.
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martinxxxxxx (10 Aug 2012), Mursal (9 Aug 2012)
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bernardgreen

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PostPosted: Thu Jun 11, 2009 6:45 am Reply with quote

The other possible fault is it there is a speed related switch that disconnects the start wind and capacitor once the motor is running at speed in the right direction. If that switch is open circuit then the motor will just hum as the phase shifted start winding is not active.
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BrianKeith

from United Kingdom

Joined: 18 Mar 2009
Posts: 6
Location: Kent,
United Kingdom

PostPosted: Thu Jun 11, 2009 8:50 am Reply with quote

Thank you all for you replies.

Spark 123. Thank you for your help. I have uploaded 3 photos, two of the capacitor and one of the multimeter as requested. If the problem is with the actual motor, I think I may give it up as a bad job. I did suspect the brushes, but reckon it hasn't been used often enough for them to wear out. I working on the assumption it's the capacitor or on / off switch.

jj4091. Thanks for the information. I don't really feel that competent to work on live equipment, but could probably find someone who is! The link is very handy. I'll check the filter.

BS3036. Thanks for the info about the switch. I'll check that with the meter.

Taylortwocities. Thank you. . The behaviour you have explained has been helpful. I carried out the test as suggested and it behaved as you have stated. Does this mean this capcitor is ok or needs replacing? (Excuse my ignorance!)

bernardgreen. I'm not quite sure I understand what you have said, but there is no hum or sign of life when activating the on / off switch. Thanks for your post.
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BrianKeith

from United Kingdom

Joined: 18 Mar 2009
Posts: 6
Location: Kent,
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PostPosted: Sun Jun 14, 2009 3:20 pm Reply with quote

Thank you all who posted a reply.
I have managed to trace the fault. A dodgy switch. Now up and running.
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Madelvic

from United Kingdom

Joined: 09 Aug 2012
Posts: 3
Location: Edinburgh,
United Kingdom

PostPosted: Thu Aug 09, 2012 9:53 pm Reply with quote

bernardgreen wrote:
The other possible fault is it there is a speed related switch that disconnects the start wind and capacitor once the motor is running at speed in the right direction. If that switch is open circuit then the motor will just hum as the phase shifted start winding is not active.

Great post. I have a Karcher that hums when powered up. If I spin the fan using a screwdriver the motor runs. Can you help with what I need to look for ie where is the switch? I assume the capacitor is inside the power 'module' with the start switch and I can check it out.
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Mursal

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PostPosted: Thu Aug 09, 2012 10:28 pm Reply with quote

No its the capacitor you need, when it starts with the fan "flick"

If it was the switch it would not work at all
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bernardgreen

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PostPosted: Fri Aug 10, 2012 6:03 am Reply with quote

It was reported as problem solved at

Sun Jun 14, 2009 4:20 pm
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jj4091

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PostPosted: Fri Aug 10, 2012 6:10 am Reply with quote

bernardgreen wrote:
It was reported as problem solved at

Sun Jun 14, 2009 4:20 pm
I think someone else has been doing a search & piggy backed this post. icon_smile.gif
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Madelvic (10 Aug 2012)
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Madelvic

from United Kingdom

Joined: 09 Aug 2012
Posts: 3
Location: Edinburgh,
United Kingdom

PostPosted: Fri Aug 10, 2012 5:43 pm Reply with quote

Forgive me my very first post to the forum - didn't realise the post was 'closed'

New capacitor on order. Will let you know if that fixes it.
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Madelvic

from United Kingdom

Joined: 09 Aug 2012
Posts: 3
Location: Edinburgh,
United Kingdom

PostPosted: Sat Aug 18, 2012 10:20 pm Reply with quote

Guys

Many thanks for your help. I bought a genuine Karcher start capacitor with the same part number (although it was slightly lower capacity, 20uF rather than 25uF, and slightly smaller physically).

Cost all of 12 inc postage. Fitted it this afternoon and I have a fully functioning washer again.

Very grateful for your help and advice
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