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Hoover Won't Reverse, But Does Spin


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Hi,

thanks for all these tips & tricks and the forum.

I have a question which sounds specfic in the first place, but I guess it could be rather generic.

My trusty old Hoover washer/dryer WD1200 (A8722) no longer reverses properly. During wash cycles it does not move the drum back and forth as it should. Sometimes it does, sometimes it doesn't, sometimes it seems to have a load problem (starts movement, but stops immediately).

It does fast spins with no problems. Also, it reverses with no problems during drying.

This led me to believe that it could be a problem with creating the EM field to start the motor, but apparently the machine (22 years...) does not have a capacitor to start the motor, that could have dryed out?

Unfortunately I do not have a wiring diagram. but I checked a few things. I have replaced the brushes 8 years ago. Then they were in service 14 years and looked like they could take even more, so I hesitate to throw them out with no clear indication.

Funny enough, on the end of every program part when it comes to draining the water from the drum - the drum reliably gets moved like there would be no problem at all. This leads me to believe this machine has more than one way to drive the motor, although it has only very little electronics.

Thanks alot for any help!

Yours
Oliver

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Wow, 22 years is almost Guinness book of records these days. I think the old Hoover washing machines just reversed the polarity with switches inside the timer to make the motor run the other way. It's possible one of the switches inside the timer has gone. I wouldn't think it's available any more or even if it was they were always very expensive.

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Hi,

yes, it does reverse polarity with a switch in the timer, it can be clearly heard. But this works okay in the drying cycle, which led me to believe it's a load problem (supposing there is only one short intervall timer for both washing and drying cycle). Without any water, the load on the motor should be substantially lower that with a filled drum. And I guess the fast spin works simply with "full power to the motor" :-)

Thanks

Oliver

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I have to agree with your diagnosis so far because if it works in one direction, it should work in the other. I am also wondering about the switches because although you have maybe measured the volts, what about the current? Is there any way the polarity switches can be cleaned? or maybe check the wiring or dry joints etc.

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Hi, maybe there is a misunderstanding. In the wash cycle the drum isn't moved in any directtion at all (until the very moment when the pump drains the water, then the drum starts moving). But that is not consistent. Sometimes the drum gets moved, sometimes the movement starts, but stops immediately. This is why I first thought "looks like a dryed out capacitor to start the motor" (but it doesn't seem to have one).

The drum does move in both directions during the drying cycle, with no problems at all!

Unfortunately I do not have a wiring diagram, so I cannot check whether there are two switches to reverse polarity or just one. At the moment I cannot measure the current (I would have to open the line running to the motor, as I do not have a magnetic current probe, and using the digital meter as a power meter is too slow (just one measurement every two secconds) to see what goes into the motor. The overall power consumption is normal.

Reading into the forum posts I got the idea that maybe I should check the pressure switch system, looking for a cutout from there. But it controls fill levels correctly (there are four - low water usage program level, wash level, rinse level, and emergency pump out level). And another idea is of course to check the brushes (but I hate the idea, they are hard to get out) or check/clean the collector on the armature to ensure enough power is transmitted.

Thanks!

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Hi,

I removed the motor and took it apart, giving it a thorough clean and checking brushes. They are more than half the lengths of new ones, 2/3 I would estimate, so I'd say they are not the culprit. Clean, evenly worn. Armature clean, too. Tacho coil seems to be okay.

Maybe this is totally unrelated, but I thinks its worth noting:

When reassembling I heard that the motor has a smooth direction of turn and one that's a little rough. Checking everything again it's one of the brush housings. No matter which brush I set in there, one direction is rough (and not the one you would expect, it's the one going away from the brush).

Putting a screwdriver on top of the brush spring the collector movement underneath can be clearly felt. The other direction is smooth. On the other brush housing both directions are smooth, also no matter which brush. Thorough inspection of the housing yields no evidence as to the source of the sound/vibration. No obvious cracks, no major misalignment (couldn't be adjusted anyhow, they seem to be riveted? to the (plastic) carrier. Brushes run with a little space in the housing, so they can move a lttle bit, but not too much. Spring looks okay. As there is a cable leading into the brushes, contact to the housing seemed to be non-essential, so I gave brushes outer surface the least little amount of grease to ease their travel (although I think that should be unnecessary).

I have heard differences in direction of turn before, but on the assembled machine it is not as obvious. And, both brushes are worn exactly the same amount...

Any ideas?

Thanks

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Check to see if one of the comm bars is slightly raised by removing the motor and brushes and placing a finger on the comm then slowly turn the armature. If one is slightly raised the armature is knackered.

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Looks like no comm bar has raised, that rough sound comes continuously and is independent on the angle of turn. With the screwdriver on the brush spring I can feel the comm bars travelling below. It sounds like I suppose an entirely worn brush would sound (but they aren't worn), when the copper reaches the armature. But there is no increased wear, neither on the brush that was in this housing, nor on the comm bars. They are clean (except for some traces of carbon, of course), evenly worn, just nice...

My guess is that in the direction away from the brush, all the comm bars slightly push the brush up, and it has slightly too much space to do so (more than in the other housing), and a couple of degrees later the spring pushes it down again. In the opposite direction of turn the comm bars dont push the brush up, but perpendicular to that onto the housing wall.

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Hm, power to the motor. Obviously. But I wonder how this motor starts in different directions, anyway. There are six wires to the motor. On the motor's terminal there are seven connectors. 2 for the brushes, 2(3) for coils, 2 for tacho. On the stationary coils there is an unused connection, supposedly in the middle, it sits on a copper bridge, maybe where once in previous designs they would have had the capacitor to introduce the shifted phase?

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After re-assembly everything works, but the rough sound ist very audible even through the machine. Louder than before. But it does work, although I could not check with laundry, i.e. heavy load. Will have to do that tomorrow. Btw, the rough sound is in the opposite direction of fast spins, this might not be a coincidence. After a full fast spin, the rough sound continues.

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If the problem was caused by a raised comm bar, the clicking would only occur once every revolution. So if the clicking is constant, as in the passing of every single comm bar the fault is more likely to be brush related. Unless by any chance you have put the brush the wrong way round, which would result in a very loud ratcheting noise all the time the armature turned it's hard to think of any known issue that causes this.


If you swap brushes round, or fitted a brush that has already bedded in to another motor it will take a few wash cycles for late to bed in properly and quieten down. If there is a lot of sparking, and the motor will not turn under load than it sounds like there is a fault on the motor. And at the age of the machine it's not likely to be worth repairing even if you could get the part. Alternatively if it only struggles when turning one way on wash then I would still suspect a faulty program timer switch. And the same applies.


On the old Hoover motors the third field coil wire was used to halve the windings on the final fastest spin.

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Hi,

new day, new findings, new theory.

First of all, let me thank you for your tip using soda crystals. For years, I have already used distilled vinegar for cleaning off limestone, but never did something special about grease (except for occasionally one of those commercial washer cleaning fluids). I found soda to be far more effective than those cleaners, and cheaper, too!

Since this is a washer/dryer, lots of lint and gunge collect (during the drying cycle), which is why I removed the condenser periodically. But the same stuff collects in the plastic drum container, too. And the amount I have seen that got removed by the soda - phenomenal!

During my soda boil cycle (and another boiling cycle with vinegar right after that) the machine did not move the drum very much, except for the start of the cycle and at the end (as soon as the drain pump kicks in, the drum gets moved faithfully...),

Today I started a regular clean cycle with some laundry - and the drum motor worked almost normally.

So I came off of the idea that some contacts inside the electro-mechanical timer might be worn. Those do not regenerate... But other parts might do that, when cooling down. And capacitors... The Cruzet timer sits on a PCB that is connected to the pressure switches, the user switches, and the motors and heater elements. Since the motor does not use a capacitor for creating an auxiliary magnetic field, I guess that the semiconductor carrying a heat sink should be a thyristor.

I do not have schematics of the machine at the moment. Although I would happily spend the euros to get one, the companies offering them on the net present demo pages that make me hesitate, because they feature explosion diagrams that have modules on them that my machine does not have, so I fear they might describe a successor model.

To me it looks like there are many ways to drive the motor. It must have, since driving it during drying cycles never fails, also when the drain pump is active. Btw, the brushes are, although they do not face the armature perpendicular, mounted (rotational) symmetrical, so there is no wrong way to insert them, and they are interchangeable. I do not see lots of sparking, and there are no burn traces at all. At the moment I suspect the springs that push down the brushes, maybe one of those does not travel freely and pushes too hard.

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I'm not saying the brushes are the wrong way round but the carbons on those old machines can be put in the wrong way round, not upside down, but back to front. They can be put in so that the curve on the face of the brush faces away from the comm bars and the only thing contacting the commutator is the thin edge. That makes a loud ratchety sound and causes the motor to lack power.

To be honest the only thing I can see causing the motor to not turn on wash but turn OK elsewhere, or to only turn intermittently, is the reversing switching inside the timer. I used to get it all the time, often if I knocked the top of the timer hard it would cause the motor to judder or spring into action as it shifted the switch inside around. The other thing I would just double check is the motor connector on the harness and motor to make sure you haven't got a connector that has pushed into the connector housing a little. I used to get that a lot too on those older machines where the small arrow-like tab that was pushed out a little to hold the connector in place was no longer holding it and if you pushed down on the male tag in the motor connector block or the female tag in the motor harness it would move down. This meant when the motor plug was connected to the motor the tag pushed down and made intermittent contact.

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Thanks for all your help. At the moment, the motor is more or less doing it's job.

You are right, it would be possible to insert brushes with the worn side facing out, but that is not case (I wonder whether that would work, because then the cable in the brushes would be far closer to the armature, possibly at the end of the opening in the brush holder). Sure, this would plausibly lead to the noise, but then on both brushes, not on only one, and ratcheting would be in both directions of turn. And I have repeatedly removed, interchanged, re-inserted, double-checked, cleaned, ever so slightly lubricated the exterior of those brushes... Anyway, whatever it is, the noise is calming down a little. At moment I don't have to spare time to remove the motor again to check my "spring is not moving freely" theory. Pushing the spring outward with a screwdriver supports this theory, (spring does touch the inner wall of the brush housing with its far end, so possibly contact may become stronger or weaker, depending on the angle of bend) but as long as the motor is in I can only feeld this, but cannot see it. Another possible explanation would be that the brushes might me slightly too thin, thus having too much space for movement. But they are genuine Hoover parts, from the central Hoover parts dealer in Munich.

The connector seems okay, I also treated all contact material with a contacts cleaner. The contacts have not moved down.

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