Author Topic: DC25 brush firing in short bursts only (Read 4070 times)

larkim · « **on:** May 03, 2021, 07:24:19 pm »

Hope someone can point me in the right direction here.

As per this video, the brush is only firing in short bursts when the power on button is pushed, sometimes at the start and sometimes at the end (I.e. when it is being switched off).

I stripped down the brush head assuming it was blocked at first but that was a blind alley. I've tested the power supply at the connector and had 240v constant on the meter.

I've also tested the DC at the motor terminals and that was showing 300v but it was switching on and off in bursts as the power supply button was pushed. I have already bought a new PCB from Manchester vacs assuming the original ocb was faulty, but I've got the same fault on putting the new one in.

Any suggestions as to what the fault might be? It doesn't feel like it's the motor as the motor seems to be doing just what the inbound DC power is telling it to do, but I'm a long way from being technically insightful as this is the first vacuum I've ever done any disassembly of!! Any help gratefully accepted!!

MVacs · « **Reply #1 on:** May 03, 2021, 07:29:09 pm »

I'd suggest it's either the brushroll motor or the yoke loom.

Look at the armature on the motor, is it shiny and coppery or black? Any raised bits or damage?

larkim · « **Reply #2 on:** May 03, 2021, 08:09:03 pm »

Thanks for posting so quickly!!

Armature looked clean.

Just taken it all apart again with the following conclusions:-
240v at connector is constant, no issues
Testing the AC inputs on the PCB, if the motor is connected I get zero volts
But if I disconnect the motor, I read 240v across the AC inputs on the PCB

I'm guessing that means that there's something goosed in the motor.

Why would it not read 240v with the motor connected if there is a fault at that part of the unit?

MVacs · « **Reply #3 on:** May 03, 2021, 09:24:01 pm »

If a solid 220-240v AC into the PCB (even when moving the machine about), circa 320v DC out of it. If that's right and the motor doesn't run, we should suspect a motor.

larkim · « **Reply #4 on:** May 03, 2021, 10:10:36 pm »

I was measuring across the AC inputs to the rectifier. If the motor is connected I get nothing. If the motor is disconnected I get 240v.

That could be measurement error in my part but I'm pretty certain that's what I was getting.

As it happens I've now blown up the rectifier as I slipped with the probes :-) but I've still got the original pcb etc.

MVacs · « **Reply #5 on:** May 04, 2021, 05:21:15 pm »

Test the DC output from the PCB and the resistance across the motor terminals.

larkim · « **Reply #6 on:** May 05, 2021, 08:08:59 am »

Thanks again; I may get round to testing that tonight, but as I'm assuming now that that motor has gone I think I'll just get a £100 machine off Amazon and be done with it. Blowing up the other PCB reminded me how inept I could be with electrics!

Is there a market for a fully working body (minus a working brush roller) for spares? I'm guessing the weight / size means that ebay isn't a popular route!

MVacs · « **Reply #7 on:** May 05, 2021, 04:11:44 pm »

Quote from: larkim on May 05, 2021, 08:08:59 am

I think I'll just get a £100 machine off Amazon and be done with it.

I'd not do that. The real cost of selling on Amazon is about 20%, that and shipping means the seller is getting £72. You cant properly refurb a machine at that price point. Caveat Emptor with Amazon and eBay.

Quote from: larkim on May 05, 2021, 08:08:59 am

Is there a market for a fully working body (minus a working brush roller) for spares? I'm guessing the weight / size means that ebay isn't a popular route!

Easy enough to ship with parcel2go.com

Maybe better just to replace the full cleaner head.

larkim · « **Reply #8 on:** May 05, 2021, 05:27:05 pm »

Actually, I meant I'd be getting a cheaper machine. Vax machines with a long reach at £100 seem OK, we actually don't have that much carpet needing vacuuming!

I'd rather recycle the machine into someone's hands than throw it away though. Will look into ebay etc.

BillBob5050 · « **Reply #9 on:** July 24, 2021, 11:18:29 am »

Hi larkim and MVacs.
I have a similar problem on my DC25, except the motor only fires for a short burst when switched on, not intermittently. You have given me a good start point for investigations.
Thanks

MVacs · « **Reply #10 on:** July 25, 2021, 04:38:25 pm »

Quote from: BillBob5050 on July 24, 2021, 11:18:29 am

Hi larkim and MVacs.
I have a similar problem on my DC25, except the motor only fires for a short burst when switched on, not intermittently. You have given me a good start point for investigations.
Thanks

Yours sounds like the motor. But again, check you have a DC 330v ish feed going to it.