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Author Topic: DC41 Brushbar problems - at a loss  (Read 846 times)

Offline Tec10000

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DC41 Brushbar problems - at a loss
« on: April 01, 2020, 04:45:05 PM »
So far I've tried everything that I can think of. Hoping that someone on here may be able to help.

Problem is the usual brushbar not spinning however, I've tried a number of things from info on this forum and still no joy.
Initially I purchased a new genuine brushbar from Amazon thinking this would immediately solve the issue. However, still no spinning of brushbar.
I have also tried:
Multiple presses on the brushbar switch - widely advised on the internet as solving brushbar issues but not in this case.
Took the switch unit apart and tested continuity - both power and brushbar switches latch on and off as expected.
Measured voltage at brushbar connectors - around 300V when inclined and powered on. Voltage drops of gradually when switching brushbar off then back to 300V when switched on again. Seems like power to brushbar is as would be expected?
Tested continuity of brushbar motor which doesn't read open circuit so guessing this too is as expected?

Can't really diagnose any faults but when the whole thing put together I get nothing.
Any suggestions gratefully received!

Many thanks
Tom

Offline MVacs

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Re: DC41 Brushbar problems - at a loss
« Reply #1 on: April 02, 2020, 07:33:05 PM »
If you’ve a steady circa 300v DC coming out of the machine to the cleaner head, it must be the brushroll motor in the head.

Offline Tec10000

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Re: DC41 Brushbar problems - at a loss
« Reply #2 on: April 03, 2020, 11:02:20 AM »
Thanks for the reply. I had narrowed it down to that but can't believe it since the brushbar is new, not even a recon unit. I will have to contact the seller I suppose. Could I do any form of testing without dismantling before sending the unit back? What readings should the meter display? I'm getting around 75 Ohms across the terminals, does this sound about right?
Many thanks again for the advice
Tom 

Online ryevac

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Re: DC41 Brushbar problems - at a loss
« Reply #3 on: April 03, 2020, 02:15:14 PM »
Is this 41 an erp version ?
You comment that you are measuring voltage output, is you meter set to dc volts ?

If you have a voltage present to the head when switching the head on but it fades away, then this means the ac supply to the control pcb is intermittent, you are measuring the dc voltage of the capacitor output of the control pcb as the electrolytic discharges.
If its an erp version then the output from the pcb is not direct to the cap n bridge rectifier - it actually supplied by a fet if i remember right.
My diagnosis... based on how i read your post is that the switch (supplying 240v ~ to the pcb in the ball) is intermittent.
Difficult at a distance, but could trace this in a couple of minutes if it was in front of me.

With no head motor connected, the 300vdc output can fool you as there is nothing to discharge the high voltage, it gets trickier if erp
The only way to fail is not to try.

Online ryevac

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Re: DC41 Brushbar problems - at a loss
« Reply #4 on: April 03, 2020, 02:51:53 PM »
HMMM
I have read your post properly now  ;D

are you 100% certain that that voltage of 300vdc is there consistently when switched on ?
If so when it is connected to a load (head motor) it could be dropping - caused by the old head motor damaging the pcb, particulary if its the erp version.
Stu is correct, if the voltage is there then the head you would have thought is at fault, but the problem here is the off and on load voltage supplied to the head.
My bet is that its an erp version
The only way to fail is not to try.

Offline MVacs

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Re: DC41 Brushbar problems - at a loss
« Reply #5 on: April 03, 2020, 04:59:38 PM »
the brushbar is new, not even a recon unit.

When you say brushbar, do you mean cleaner head?

Offline Tec10000

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Re: DC41 Brushbar problems - at a loss
« Reply #6 on: April 07, 2020, 10:54:20 AM »
Thanks for the responses guys, it is much appreciated!
the brushbar is new, not even a recon unit.

When you say brushbar, do you mean cleaner head?

Yes, sorry my terminology was off. It is the cleaner head that I'm referring to not the brushbar as stated.

HMMM
I have read your post properly now  ;D

are you 100% certain that that voltage of 300vdc is there consistently when switched on ?
If so when it is connected to a load (head motor) it could be dropping - caused by the old head motor damaging the pcb, particulary if its the erp version.
Stu is correct, if the voltage is there then the head you would have thought is at fault, but the problem here is the off and on load voltage supplied to the head.
My bet is that its an erp version

Yes, correct it's the ERP version. (If i'm correct in thinking that the red slider on the cleaner head is the giveaway)

In the power on + leaned back state I am getting a steady 300V. However, I tested this with the cleaner head removed and the meter probes inserted into the cleaner head connectors that come from the ball section. So this test was done without the motor load - could this be luring me into a false sense of security with regard to the state of the PCB? I would expect the voltage to drop off over time after switching off as the large capacitor on the PCB discharges which was confirmed by testing. However, I have no frame of reference for this so don't know what to expect.
Should I be testing the voltage with the cleaner head in place? If so, what's the best/safest method of probing this setup with a meter? FYI - I have an the old and brand new cleaner heads that could be tested for cross comparison if this of any use.

Many thanks  :tiphat:

Online ryevac

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Re: DC41 Brushbar problems - at a loss
« Reply #7 on: April 07, 2020, 12:39:34 PM »
Hi 
Yes i think it could be a red herring.  "Erp version confirmed"
If you are using a brand new head assembly then i would say the ball pcb is faulty, it is possible as stu says to have a faulty new head and that is what it could point to.
 
The non erp version pcb output with no head connected would give you 320+vdc ish and would discharge in a few minutes as there are 3x 68k resistors in series over the dc output (204k) as a discharge load. This non erp version is a very basic full wave bridge rectifier,couple of inductors, reseviour cap and discharge R. nothing complicated with that.

To have 300v is correct i believe from an erp version, and looking at the circuitry on the pcb i would say that if you measure voltage then turn machine off that 300vdc will vanish within a couple of seconds but with a load on it will not produce anything. This is due to control circuitry and possibly current sensing ?

Either you have been very unlucky buying a faulty new head, very unlikely but not unheard of, or the original head motor failed - destroying the pcb. not uncommon.
The seller will probably refuse a return of the head, and will have had this experience many many times with buyers.
I would strip the new head so you can measure the voltage over the motor whilst connected to the machine, and my bet is it will fire up for 0.5s then drop to 0v when switching the machine on.

I assume that the yoke cable is good,? another red herring thrown in,,, i have seen similar problems with one of the wires almost severed, and arcing inside the insulation, the carbon created by the arcing is enough to pass a voltage to measure with a meter but obviously not passive for current. seen this in many industrial applications at vauxhall motors production line robotics looms years ago, we were building and supplying add on monitor units for them.

Ideally you could do with a dummy load instead of the head, (i should make one tbh) a resistor with a value of 600ohms should draw 500ma for testing, but needs to be high wattage (150watts ?) and then measure the voltage.
The erp pcb is VERY different to a non erp pcb, not really done much with these as a repair to an erp one would probably cost more than a new one.
Here are some pics of the pcb's.
erp underside
ila_rendered
erp top
ila_rendered

Careful if buying a used erp pcb, as some sellers do not know the difference and cannot confirm it to be working, they scrap and strip faulty vacs, assumming the head has failed and sell the pcb not knowlingly faulty !

This subject repeatedly occurs, and covers most models with powered motorized brush heads, people think it's the brush head at fault, order a new one then fall in to the trap. most common is the dc25/dc40 for me, and the yoke cable is more often to blame, it like playing darts in the dark with a blind man trying to do the marking.
(sometimes it is just the brush head)
Many get to this point of diagnosis and give up, and the forum has many related posts.

However i could be wrong.....
The only way to fail is not to try.

Offline Tec10000

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Re: DC41 Brushbar problems - at a loss
« Reply #8 on: April 07, 2020, 02:12:38 PM »
Thanks for the in depth post!

My plan of action is now going to be:

Strip the new head back to a point where I can test voltage across the motor whilst connected - looking for the values as suggested
Check the yoke cable for signs of wear and tear + arcing as suggested.
Strip down ball to get to the PCB and look for burned/damaged components - Buy and fit brand new (ERP version) PCB.

I'll post back the results when I get to the bottom of it - I am determined not to let this one go the way of the last one
I think you're right when you say that many people get to this stage and give up! Cheers for the help

Online ryevac

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Re: DC41 Brushbar problems - at a loss
« Reply #9 on: April 07, 2020, 02:21:28 PM »
Ok, i think that is key,  monitoring the voltage whilst the head is connected. I would suspect you will see the motor turn very slightly at first then nothing if my suspicions are correct.?
just do it in modules,  another known working machine to test your new head on would have been easier for diagnosis.
Good luck and let us know the results.
The only way to fail is not to try.

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