Panasonic upright cleaner now back in business! Next, the Hoover PurePower

[MM]

I've fitted the new thermal fuse and bingo! It works again. Now for the Hoover PurePower 1900w.

However, the cut-out on the Hoover is different in that the thing cuts out, then you leave it for two to three minutes and it will start again. The time until cut-out gets shorter and shorter.

The Panasonic's fuse OTOH was a one-time "blow", never to work again, which figured, as it gave no warning at all when it stopped working.

So, my question, before I start dismantling the Hoover: will the thermal fuse look similar to the Panaonic's e.g. one of these:

will it be a different shape? Will it be an inline thing in the brown cable like on the Pansonic, or a little black box with connectors?

By the way, the repair for the Panasonic cost me 69p for the fuse and £1.29 for a 10x packet of crimp-on butt connectors, 9 of which I've got left.

MM

[Dave Plowman (News)]

A re-setting one. I had a Plasplugs tile cutter that did that. Don't think any series wound motor can cope with continuous use - unless very well cooled.

Probably quite a bit larger. But of course it may be tripping for a reason. Make sure a bearing hasn't seized, etc, and that the motor cooling hasn't got blocked.

It gives you a nice warm feeling. Especially when a Maplin shop actually stocks some components. ;-)

[Andrew Gabriel]

The thermal fuses tripping are normally symptoms of another problem. Did you identify what the original problem was?

there are other styles.

However, you should be fixing whatever is causing the overheating. It sounds like the thermal switch is working fine. (These ones can go wrong and develop contact resistance which self-heats them, but that's not what I would assume to start with.)

More likely faults are reduced air-flow (hence insufficient cooling) caused by blocked airway or filters, motor bearing over-heating, motor winding shorted and overheating (often caused initially by over-heating due to reduced air-flow).

[Alan]

In message , MM wrote

The cut-out will be mechanically fixed to something that is getting too hot. Switch the appliance off for a couple of minutes the faulty item will cool down to the threshold point below which the correctly working cut-out kicks back in. The faulty item will still be very hot and it will not take much to heat it to the upper temperature threshold point of the cut-out again.

Assuming no problems such as shorted windings, it may be that on dismantling the Hoover you may find an accumulation of dust or lint restricting airflow to something that is normally cooled in a forced airflow.

It may be something like a thermal switch

[Fredxx]

Pure age can be another. I've had a few go on items like chip fryers where there hasn't been any over temperature.

[MM]

I completely dismantled the motor and housing etc. There WAS a fair bit of carpet fluff in the impeller part of the motor, but on reassembling everything after a thorough clean the cutting out still occurs.

MM

[MM]

Not until I dismantled the motor and housing. The impeller part of the motor (inside the big round mounting boss) was stuffed full of carpet fluff. I had to use tweezers to prise some of it out.

However, after a thorough clean and reassembly, the cutting out still occurs.

Having now dismantled the machine I have not found ANYthing that could be a thermal fuse, at least, not at the motor end. Inside the handle there is a small PCB (approx 50mm x 40mm) to which the cables to and from the switch are connected. The PCB has what looks like a capacitor, since it's marked uF. It is yellow, rectangular, about 20mm x 15 x 5. There is also a resistor and what looks like a voltage regulator.

Could the thermal protection be an integral part of the motor?

MM

[Andrew Gabriel]

Does the motor spin freely by hand (or are bearings stiff)? Does motor slow down before cutting out? That can be caused by windings which have been damaged by overheating and start shorting out.

Could also be knackered brushes, although failure symptoms are usually a bit different.

Probably interferance suppressor.

Yes.

[MM]

Yes.

No. It just stops as if I had switched off the switch.

No, the brushes are fine. The machine has had very little use.

That's what I think. The Panasonic also has a cap, but it is just loose on the wires, not mounted on a PCB.

That would be the worst situation, since new motors (I'm told) are unobtainable for this model. Even if they were they'd cost more than an equivalent new machine. One web site I looked at said £59.99 (for the motor [though not in stock and no info re restocking]) and I only paid £34 for the machine in the first place.

Thanks for getting back to me. The Panasonic is still going great guns! The Hoover looks like it's destined for the tip, though, since I expect the motor is a sealed unit. It looks pretty much like it.

MM