Mulcher - big capacitors!

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Mulcher - big capacitors!

Postby Andrew Davie » Wed Jun 12, 2019 11:13 pm

I need some electronics advice. I have moved house and along with the house comes a garden mulcher (Yardeco Recycler 2000).
The mulcher doesn't work, and when powered up the control box starts smoking. The smoke is coming from one or both large capacitors inside.

One is a CBB60, and the other a CD60.

Markings are hard to make out, but it looks like

CBB60 / 40uF +/-5%
450VAC ... 50???? (Hz????)

CD60
200uF ...????.....-+30%
300VAC 50/60Hz

So, Ihave a few questions.
Firstly, I'm treating them as dangerous. It looks like the smoke was coming from the CD60 but I assume both.


1) Why would they be smoking - is it possible if the engine was siezed or too hard to turn?

2) I should use a resistor to discharge them, right? Before attempting removal.

3) There are a bunch on eBay of these types - I assume it is OK to buy something with similar specs. But failing finding the exact specs...

4) If the CD60 is 300V, can I replace with one labeled 450V but same nF, or is this a no-no?

5) Should I just give this up and find someone competent to do it?

Thanks
A
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Re: Mulcher - big capacitors!

Postby Dave Moll » Thu Jun 13, 2019 6:26 pm

My first thought is that something (as you say, such as a siezed motor) is stressing the capacitors. If this is the case, replacing the capacitors is likely to result in the destruction of any replacements, so only worth trying if they are available cheaply (which I suspect is not the case for such hefty items). How feasile is it to check out the rest of the setup to find a cause of stress?
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Re: Mulcher - big capacitors!

Postby Andrew Davie » Thu Jun 13, 2019 9:13 pm

Dave Moll wrote:My first thought is that something (as you say, such as a siezed motor) is stressing the capacitors. If this is the case, replacing the capacitors is likely to result in the destruction of any replacements, so only worth trying if they are available cheaply (which I suspect is not the case for such hefty items). How feasile is it to check out the rest of the setup to find a cause of stress?


Thanks for the answer. The handyman who got it mostly functional said the motor was siezed and the brushes? weren't clean so there is definite resistance in the motor. I can turn it by hand, but it's nowhere near free-turning. Not difficult to turn, but definite resistance. So, given the motor still turns when I start it up, the capacitors are basically functional... could I kind of turn it on for a few seconds. Then off, wait a few minutes, repeat... and eventually get things running? Is that a stoopid idea?

I've got the whole thing under the workbench so if anything blows up I'm unlikely to be hit by flying shards of stuff.
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Re: Mulcher - big capacitors!

Postby ppppenguin » Fri Jun 14, 2019 2:41 am

These are motor start and/or run capacitors. So it's an induction motor which doesn't have brushes. 40uF motor run caps aren't expensive: https://www.amazon.co.uk/Universal-Micr ... B00F5VW9A8
Neither are 200uF motor start caps expensive. Just google for them, they're pretty standard parts.

The big difference between start and run caps is that the start cap is usually much higher value and electrolytic. It survives because it's only in circuit for a few seconds at startup before being disconnected automatically by a centrifugal contact. if it stays in circuit for too long it will smoke or worse. Run caps are designed to take the rated voltage indefinitely.

Lots of diagrams and other stuff here:
https://www.google.co.uk/search?q=induc ... bHM0PumbMM:
Jeffrey Borinsky www.borinsky.co.uk
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Re: Mulcher - big capacitors!

Postby Harry Dalek » Fri Jun 14, 2019 10:30 am

The one i had lucky for me just tripped a reset fuse when it played up ...and you just had to free the motor so it could turn and press the rest button so just a jammed branch that was to big ...
I don't like the idea of it smoking sounds like the coils in the motor have over heated and copper coils have fused ...if there's smoke its too late for it i think .
May be test the resistance on the coils ...Troy just had the same sort problem with an ac motor on a 60s vcr fused coils .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Mulcher - big capacitors!

Postby Andrew Davie » Fri Jun 14, 2019 1:15 pm

Harry Dalek wrote:The one i had lucky for me just tripped a reset fuse when it played up ...and you just had to free the motor so it could turn and press the rest button so just a jammed branch that was to big ...
I don't like the idea of it smoking sounds like the coils in the motor have over heated and copper coils have fused ...if there's smoke its too late for it i think .
May be test the resistance on the coils ...Troy just had the same sort problem with an ac motor on a 60s vcr fused coils .


The smoke was coming from the capacitor, I'm pretty sure!
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Re: Mulcher - big capacitors!

Postby Harry Dalek » Fri Jun 14, 2019 6:03 pm

Andrew Davie wrote:
The smoke was coming from the capacitor, I'm pretty sure!

leaky caps they are goners now Question is why ...mmmmm ,replacements higher voltage rating is better but as you think the value tends to go down at higher voltages but not cost that goes up I might have spares..
I have no idea of the wiring of the thing i would think its AC starting capacitors needed
i have 2 30uf at 470v ac i think very large....... 470uf at 250 v dc ...a few 1ufs at 2100v ..2 uf at 400v 2 430 uf 250v dc welcome to any thing here will take snaps if interested they are again large caps might have more have to have a good look tomorrow.
I think the 30 uf Ac ones would be of use if you want them...send pictures tomorrow
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Mulcher - big capacitors!

Postby Harry Dalek » Sat Jun 15, 2019 9:41 am

Hi Andrew
Welcome to any thing below
Here are the caps i have close enough they are motor Ac starting capacitors 30 uf in the mid 400 v range
it says 420v ac 10000h below it marked also 470v ac 3000h
below that also marked 240v Ac 60hz
protected 10000 afc
Think those are your best bet
DSCN9804-crop.JPG

i also have a few large dc caps
430uf 250v DC caps
DSCN9797.JPG
Attachments
DSCN9804.JPG
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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