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Author Topic: DC37 won't start, already replaced power switch, what else could be wrong?  (Read 1447 times)

Offline dc37owner

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I have a DC37 (bought in Canada) and while I don't see a dedicated forum for it here, it's extremely similar to the DC39 (in fact, I used the photos in the DC39 stripdown thread to help me take it apart).

The original symptoms were:

1) Vacuum wouldn't shut off until I unplugged it
2) After cleaning filters and letting it cool down, I plugged it in again but same problem - power switch had no effect and I had to unplug it
3) The next time I plugged it in, the opposite happened - it wouldn't come on. Sometimes, I'd hear a faint, intermittent whir from the motor, but it wouldn't stay on. There was no burning smell or any other indication of a motor failure

At this point, I figured the power switch was the most likely culprit, so I ordered a replacement and installed it. But no luck, the vacuum still won't start :(

So...any idea what else could be wrong, or what else I can check/test before giving up and contacting a service center? Again, the motor appears fine and I never detected any odors or smoke. The power cord also doesn't appear damaged in any way.

Offline wolf

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Does this model have a pcb fitted, if so  from what you have explained this
would be the culprit, its an electronic switch some of us call it a slop start circuit which regulates the voltage
 the motor would start off slow and build up very quickly to full speed   :thumbsup:
wolf

Offline dc37owner

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Does this model have a pcb fitted, if so  from what you have explained this
would be the culprit, its an electronic switch some of us call it a slop start circuit which regulates the voltage

To be honest, I'm not sure - I never saw anything like that when I took it apart, though I didn't remove the motor from its housing (like I said in my first post, the DC37 seems practically identical to the DC39, and when I look at the photos in the DC39 stripdown thread, I don't see anything that looks like a circuit board). But speaking of photos from that thread...

Dumb question - could the PCB be located here?

ila_rendered

That is, inside the black plastic casing attached to the motor where the wires are coming out? I'm no expert in how the motor is assembled; I was hoping this would be a simple case of replacing a faulty switch (which, once you get the vacuum disassembled, seemed like a fairly straightforward process).

Online ryevac

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Maybe you had a faulty switch and you have a bad motor too ?
The black plastic profile looks like the usual brush housing, do you have another photo of the wire entry points ?

Are you in uk ? you say you bought the dc39 in canada - has it ever worked wherever you are ?

I would remove the brush assemblies and ensure plenty of length on the brushes and they aren't seized etc.

Then (if its a 240v motor) ?  i would connect it direct to the mains using a safeblock to test.
Based on the info in your first post it points to motor failure. I always clean the commutator up with a fibreglass pen too.

Finally i would also carry out a coninuity test on the mains cable plug to motor feed points to rule out a bad, stressed cable or high resistance point possibly.
If it was assembled it can be disassembled - if we can't repair it then it probably isn't worth repairing !

Online MVacs

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The chap is in Canada so this is a 120v machine.

The DC37 is a DC39 but badged DC37 for Continental Europe and Canada.

There should be no PCB in this machine, its a cable rewind, power switch and motor. The motor looks OK on the photo. You need to test the rewind and switch with a meter.

Online ryevac

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In that case i would say the switch was originally at fault, but the motor has had it too IF it defo had 120v to it. The slow start up, as mvacs suggests could be a high resistance point somewhere on the cable, but more likely and the rewind assy ?
If it was assembled it can be disassembled - if we can't repair it then it probably isn't worth repairing !

Offline dc37owner

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The chap is in Canada so this is a 120v machine.

Yes, that's right, I'm in Canada.

Quote
The DC37 is a DC39 but badged DC37 for Continental Europe and Canada.

Thanks for clarifying that - I wasn't sure at first if they were truly identical save for the model name and voltage.

Quote
There should be no PCB in this machine, its a cable rewind, power switch and motor. The motor looks OK on the photo. You need to test the rewind and switch with a meter.

To be clear, the photo isn't mine - I simply grabbed it from the DC39 stripdown thread to illustrate what I was talking about. But since the DC39 is pretty much the same as the DC37, the photos in that thread show the same parts I was dealing with.

I'd be quite surprised if it's the motor that's gone, since I never detected any burning smell. Also, I don't think I ever had a problem with slow startup - more like NO startup (that is, first the thing wouldn't shut off unless I unplugged it, then it developed the opposite problem and wouldn't come on. Then, at one point, it kind of stuttered (like a vacuum would if it the plug was jiggling around in a loose outlet) only to shut off again and not come on)

All that led me to think the problem was being caused by a faulty switch, but since I've gone ahead and replaced it and still can't get the vacuum to turn on, I must (assuming the motor's still okay) be dealing with some other kind of power interruption.

So...dumb question again (since I'm no electrician) - how exactly do I check the cable rewind? I never took the motor out of its assembly (and was afraid to as I didn't want to damage any wiring) - referring to the DC39 stripdown thread again, which photo shows the wiring I'd need to look at? What's the type of meter I'd need to get to check the voltage?

...or maybe we're getting to the point where further do-it-yourselfing is above my pay grade :) That's okay too; I just want to make sure I've exhausted all reasonable attempts to fix it myself.

Offline macman

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All you need is a cheap multimeter or continuity tester. You need to check for continuity between the wall plug and the point at which the cable rewind is connected to the motor terminals (and all points in between; the cable, rewind, and plug).
No voltage required, this test is done with the machine unplugged.

Online MVacs

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All you need is a cheap multimeter or continuity tester. You need to check for continuity between the wall plug and the point at which the cable rewind is connected to the motor terminals (and all points in between; the cable, rewind, and plug).
No voltage required, this test is done with the machine unplugged.

This.

Even a battery, a bulb and some old wire will let you test continuity this way. How we did it as kids before neons and meters were the norm: old car battery, bit of old flex and a 12v bulb.

Online ryevac

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"When" i get time soon i will do a basic video on basic continuity testing etc, as subjects keep cropping up.

If it was assembled it can be disassembled - if we can't repair it then it probably isn't worth repairing !

Online MVacs

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Re: DC37 won't start, already replaced power switch, what else could be wrong?
« Reply #10 on: January 31, 2018, 11:21:20 AM »
"When" i get time soon i will do a basic video on basic continuity testing etc, as subjects keep cropping up.

Good idea. Do those symbols on the meters that no bugger knows what they mean too.  ;D

Online ryevac

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Re: DC37 won't start, already replaced power switch, what else could be wrong?
« Reply #11 on: January 31, 2018, 05:33:34 PM »
I knocked up a video this aft regarding the issue on the basics Stu.
Interesting to hear peoples opinions, i aint very good at doing videos...  :snivel:
If it was assembled it can be disassembled - if we can't repair it then it probably isn't worth repairing !

Online MVacs

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Re: DC37 won't start, already replaced power switch, what else could be wrong?
« Reply #12 on: January 31, 2018, 08:22:25 PM »
Bob on that!  :thumbsup:

See your PM.

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