OT appliance help OT

WAG they usually put some sort of over temperature protector near the heating elements, in-line with their power connection. May look similar to a resister and be clamped down, senses the heat where it is clamped. Normally they open up (too hot, plugged/restricted exhaust, lint build-up), but maybe it has shifted or shorted to the clamp area.

Is the computer/control board served by a separate fuse? A shorted rectifier to make DC for a computer-type switchmode power supply would have this symptom, sometimes.

Shorted 'start' winding on drive motor?

Older generation schematic is *much* easier to read: There are many drive motors to choose from and Maytag is *very proud* of all of them.

(I'm dubious about the fuse or thermostat as a possibility. Sorry Leon.):

Fuse and Thermostat 6th item down:

--Winston

The wiring/schematics sheet is still with the dryer and it's not that complicated . Sorry Leon , your solution doesn't fit the symptoms . Somethin'g shorting both legs to ground at startup , and I can't figger out what it is . The motor starts to turn , the fuses blow . He's only got 30A fuses on this thing , but until recently it's run just fine . I haven't yet found the spec'd fuse rating , but I'm starting to think that 30's were marginal , and as the dryer has aged and parts worn , the marginal fuse ain't cuttin' it anymore . Seems to me that most dryers are set up with a 50 amp breaker ... and yet , the motor was the only load , I had it on "fluff" with the heater shut off . Might be the infinite heat control ... I think he's just going to go get a new unit , this one came with the house and we know nothing of it's history . We could easily approach the price of a new one throwing parts at this one .

step 1 - remove belt from motor, set dryer for air only (no heat), try again, watch motor carefully - could be a short to ground inside the motor, more likely a problem with the start circuit. Even better if you could disconnect the element entirely

If the motor won't start and run with no load and no element, then either there is a short in the wires to the motor (which you can find by feeling them after the fuse blows - the problem area will be warm), or there is a failure of the motor start circuit, or a bad motor. I would probably remove the motor and bench test it - on most maytags the motor comes out quickly and easily.

If the motor runs with no load, check for undue friction in the drum, if all is well, with element still off/disconnected, hook belt up and try again

proceed in this manner to isolate the problem

Last test was with the drum removed , the timer on "fluff" (no heat) and the heat control all the way down . HmmmPOP the motoer starts to turn , the fuses blow .

I've inspected the wires , all the way . No insulation breaks , no chafing . The motor windings have the proper (approximate) resistance and are not grounded . And a motor fault would only blow the fuse on that leg ...

I'm thinking it's in the controls , some of which are pretty spendy . Timer is OK , haven't opened the others . Got 'lectronics ...

snip >

let's assume for a minute that it is NOT the motor - disconnect the wires going to the element, so the element is NOT in the circuit, and inspect the board that drives the element - I'd expect it to have a relay to energize the element - look at how the board is powered and trace the 220v across the board (with power off - follow the circuit traces) - if possible, disconnect the side that doesn't power the motor (is the motor really 110?, usually a

220V connection doesn't include a neutral) -

or, as an alternative, unplug the motor and try turning it on - if it blows a fuse with the motor not connected you can pretty well rule out the motor. You can substitute a lamp for the motor so you can see when it's energized

Snag wrote in rec.crafts.metalworking on Thu, 7 Oct 2010 15:58:07 -0500:

That would be my guess. Can you disconnect it and try it then? You say fuses, but to you mean circuit breaker? They can go bad over time, and they are built to open rather than not open.

The house the boy bought still has fuses ... and tomorrow or saturday I'll be shopping for a new dryer with him . He believed us when we told him "save money , then when the (insert appliance , etc) dies , it'll be an inconvenience and not a disaster" .

if the house has gas, that is a much cheaper way to dry clothes

The homeowner should be shopping for a new service panel, even before a new dryer. Around here (western PA), banks won't finance, and I don't think insurers will cover a structure with a fused service panel.

Motors can develop insulation current leakage which a DMM resistance test will not indicate. A motor with suspected leakage needs to be checked at operating voltage (or better yet, Hi-pot tested with a Megger-type tester). Contamination inside the motor can cause leakage paths.

It's likely that something else may be involved in the overall scenario. As you suggested, a 120V motor probably wouldn't take out both fuses.

Fuse box hardware generally always loosens with age. Vibration (even though it's not felt continuously) and thermal cycling will lead to loose fasteners.. especially when many fused panels are over 40 years old. Loose fasteners anywhere in a circuit will increase the resistance in circuits, and usually break down from excess heat.

A qualified, experienced and knowledgeable electrician should replace the service panel.. if a homeowner fits that description, that person could probably perform the installation in a couple of hours.

(...)

I changed my mind. Shorted heater element. Disconnect the 'high limit' switch and I bet it fluffs just fine.

(...)

Good call. Perhaps Craigslist?

--Winston

It does , and his cousin the gas-certified plumber lives there with him . Wonder if we can talk him into plumbing the gas in lieu of rent ... since he's not busy right now and is behind on rent !

My meter sez it'n not grounded anywhere in that circuit . Pretty much narrowed it down now to one of the control devices , and the ones it could be are both spendy . He doesn't wanna mess with it , and he's got the money saved for a replacement unit . Smart boy ! Plus I'll get some more nice flat sheet metal stock for my pile ...

snipped

A replacement panel is in his plans , and he's saving towards it . It took me a half-day to replace mine , had to modify the conduit runs because the new box is (quite) a bit larger than the original ... his is going to be more of the same , plus his is recessed into the wall and not in an easy spot to get at .

Just FWIW, (as a thought exercise only) you could cut the ground pin off of the dryer plug and still take out both fuses if the heater element were shorted. (Short L1 to L2 and things get sparky.)

I agree. (Freecycle, Estate sale, Craigslist)

Cool.

--Winston

depending on the exact situation, you can mount the replacement panel elsewhere, run large conduit to the old fuse panel, and just use the fuse box as a junction box. Frequently, the new box needs to be outside because it has the meter as part of the box, so most of these have a group of circuits that feed the old fuse box, and then additional circuits to feed other new stuff that is direct and not routed through the fuse box

Please explain how a blown fuse would short the other two out. ?

-- You can't wait for inspiration. You have to go after it with a club. --Jack London

I think that isn't what whit3rd is suggesting (although it's possible for a big fuse to spray metal onto other circuits, if given high enough current and voltage) . Instead, the question probably is where the control board is in the circuit, relative to the fuses.