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Dishwasher References - Dishwashre Maintenance Tips - Frequently Asked Questions
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Thanks for providing a useful set of information regarding servicing Neptunes!
A couple of notes that you might want to include:
In the discussion of spin failures, R11 on the machine control board is not a diode (otherwise it would be D11). As someone else noted, it would be a resistor. I cannot find it on the scan on your site; you might want to include an arrow, or some rough indications of where it is, and how you can tell when it's 'burned'. You can determine the value of this resistor via the color code printed on it (I don't remember this offhand but there have to be thousands of Web references for it) -- if a given board's resistor is burned too badly to read, a good color picture of an INTACT board would give the necessary information...
Thankx to our friendly engineer Ohmie....one new arrow picture
The door lock light switch and the spin inhibit circuit are two completely different things, at least on the 4000; it is quite possible to have a 'lit' indicator, and a locked door, while still getting spin. Complicating this, it turns out that Maytag has, indeed, designed the control such that the machine tumbles during an inhibited spin, rather than 'just sitting there'. I suppose we should be grateful that it gets SOME of the water out of the load in this case. Here is Maytag's 'quick' problem check (I leave out the safety steps and precautions, but of course follow them):
Get to the machine control board via the procedures described. (There ought to be a very good wiring diagram and troubleshooting chart in a clip on the left-hand side of the backplate, btw.) Set the timer to a spin 'increment'. With a VOM, check for 24VDC at the following points:
Connector P2, wire 4 (this is an orange wire, numbered 40) to reference connector P5 (which is all the way to the right of the board). This is the out-of-balance circuit, and according to Maytag, this gets 24VDC as soon as the washer is started at any part of the cycle, but is only 'scanned' by the computer logic during the spin cycle.
Connector P3, wire 7 (yellow, 36) to P5. This is the ACTUAL spin-enable circuit, not the light. It needs 24VDC showing if the washer is to spin. (Note that you can block the microswitch in the Door Switch Assembly manually if you have to get a few loads done before the parts place opens, and the washer will then spin).
With the AC plug disconnected from the wall, check continuity from Red 23 (I accessed this at the common side of the Options Switch, but it is also Connector P3, wire 1) to P2 Wire 4 (orange 40) mentioned above. There should be no break (e.g., very, very low ohm reading on a VOM) between these points. There are three NC switches in series that detect excessive displacement and imbalance, and if any of these is open or a wire detached, the spin will be inhibited as above.
About the damn wax motor: It is, in fact, just that. It is NOT a solenoid with a coil. I believe it is similar to an automobile thermostat, in that it contains a special wax 'button' that expands with increasing temperature. When line AC is connected across the wax-motor terminals, there is resistance heating, the wax expands and pushes a plunger inside the motor housing, and the protruding actuator comes out against internal spring tension. You can NOT go inside and service this thing: the plastic tabs that hold its case halves together are intentionally made fragile, and will break off even if bent only slightly. Continuity testing will tell you little, if anything, about whether it's operating properly. Verify that there is 120VAC across it (this is between Connector P7, wire 4, brown 14, and reference neutral, white 13, which is neutral on the wall plug and can be found at orange 12 at the (open) door switch IF the tub light bulb is good). But even if power is there, the only way to test the motor is to see if it elongates when power is applied to it. A straight ohm reading won't give you any useful data about whether or not the motor is operating or 'shorted' (I got 1.003 ohms from my defective motor, with no observed heat rise/dissipation, and I have no idea what the 'proper' AC resistance/impedance ought to be here, or how to measure it.)
It might be useful to find a source for this wax motor component, as it seems a shame to replace the entire Door Lock Assembly, with the switches and other components, when it's so easy just to replace the motor (two AC leads, a leaf spring at the left side, rotate to get the tip disengaged). * ( Webmaster note: - The entire door lock/latch assembly will soon be no longer available and only the separate items will be available ) I'm tempted to design -- and I encourage you to design --some kind of manual positive latch to replace the electric one (along the lines of the manual 4-wheel-drive actuator replacements for recent GM trucks, which also have a 'thermal' actuator that often stops actuating...). I assume, correctly I think, that the only 'control' input for this motor is the presence or absence of line AC across its terminals, and there shouldn't be any difficulty in simply replacing this component PROVIDED that AC is detected, as above, across the motor terminals or between P1 wire 4 and line neutral. This is implicit in the Maytag troubleshooting flowchart discussion of spin problems.
Some notes on Maytag Neptune wax motors:
According to Maytag customer service, it doesn't appear the new 'solenoid' door-latch assemblies will work with the machine control boards in the 3000/4000 series machines. The technicians who know 'for sure' won't be in before Monday, but I suspect this information is accurate anyway.
Maytag has, however, redesigned the latch assembly to use a different kind of wax motor (the person I talked with didn't know exactly what changes were made, but I might presume the result is more robust). The part number I was given for the REVISED version is 22003467 (not 22003465, which is what all the Internet parts services I consulted gave me as the replacement P/N for my MAH4000AWW). I had the Maytag people check this revised P/N twice to be sure. Moral here: I would STRONGLY advise anybody with one of the earlier Neptunes to put this board in if there's trouble with the latch, machine control, etc.
There is also a positive way to test the machine-control board for 'soft fa ilure' of the wax-motor drive circuit, if there's any question about it. This consists of applying a service resistance load across the wax-motor AC drive circuit, equivalent to the motor load at 'peak draw' (which is right at starting, when the PTC starts to heat and is drawing full heating current).
Maytag reports that the 'retracted' (e.g., cold) resistance of the wax motor is 1900 ohms (and I presume this is straight resistance, with no reactive component, since it's essentially a PTC and resistance heating). My multimeter detected 133VAC across the wax-motor terminals at latch request. This translates into 0.07 amps, which in turn translates into 9.31 W. So, unless I've missed something, using a 120V 10W light bulb across the wax-motor leads should prove, definitively but without breaking or igniting anything, that the board is sourcing sufficient current to drive a replacement motor without a control-board change out.
Let me know if there's a mistake in any calculation or assumption here!
Slight addition to the MAH4000 stuff I sent yesterday:
If you open the Maytag wax motor, the actuating plunger is held in the retracted position by a very, very substantial spring (so the device can be thought of as 'normally off' with respect to the door). Somebody on a list was trying to say that wax motors work by spring action: when the wax softens and melts, a spring moves the plunger. That is most certainly not the case with Maytag's device.
The actual wax motor is a very small square cylinder of plated metal, with a pin-ended 'piston' (the pin engages in a mating hole in the rear of the actuating plunger and controls any tendency for the actuating plunger to shift sideways and bind under its high spring tension). There is a small disc soldered or brazed to this cylinder at the rear, and the AC actuating current runs laterally through this disc and the rear of the cylinder, through spring contact with the terminals inside the case.
As it turns out, the disc is a PTC thermistor or similar device, and the metal cylinder is just the "lead" path that connects to the other terminal. At least one manufacturer of these devices has a Web site with descriptions and some statistics. In this particular switch, actuation is "bang-bang" -- AC across the terminals causes the PTC to heat up to the point where its resistance effectively balances current flow, at which point the heat, passing to the cylinder, heats the wax, expands it, and extends the actuating rod against spring pressure. Advantages: 'guaranteed' limited current, soft and relatively slow actuation, positive engagement. One potential difficulty in Maytag's design: there are dogs in the two halves of the door-lock mechanism, which prevent the door lock from actuating if the door isn't closed. In this case, if the wax motor were to (accidentally) extend sufficiently to compress the spring inside, I see no indication that there is any resiliency back along the rod and piston -- this might hold the lock closed with sufficient firmness that even slamming the door might not get the lock to engage without breaking something (even though all the working dimensions in these parts of the lock are pretty generous).
Two things argue that the attractive engineering picture isn't quite as attractive in practice:
First, the reported large numbers of failures of the latch motor in service, some of which evidently result in current runaway and machine-control-board failures (presumably at R11, although I couldn't confirm this without a board wiring and logic diagram). If the PTC fails in certain ways, you can get what amounts to a near-short across the AC supply (!) -- in my case, light blue wax had leaked out of the cylinder and around the lower curve of the PTC disk. There was some evidence inside the case of blackening (which to me implies carbonization; carbon is a relatively good conductor at 110 V.
Second, I note from one source that Maytag has redesigned the door lock assembly in the current run of MAH 5500s and 7500s so that it works with "solenoids" rather than wax motors.
Hope you find this useful in some way!
Many ThankX to RME for providing some extra insight into these washers!!
Thanks for the excellent web site. May I give you some help, then maybe you can give me some.
You do not recommend repairing the board. I do, with qualifications. 1: IF! The board has not been seriously burned. and 2: That you change Q6 out with an MAC97A8 rather than the "as issued" MAC97A6. At the same time change Q3, Q9 and Q17 with MAC97A8's. The "as issued" MAC97A6, 400 volt triac, is the problem with the door (Q6), the timer motor, (Q3) the cold water valve, (Q9) and the hot water valve (Q17). R11 is a 3.9K 1/4w 5% CARBON FILM resistor. If the wax motor has a metered resistance of 1900 ohms ±5% or so at room temperature, and has no obvious signs of smoke, it is probably still good. The wax motor uses a NTC metal oxide varistor as a heater, it may read 10% higher or lower then the 1900 ohms depending upon its temperature. Contrary to Maytag's belief, the triac (Q6) failing, takes out the wax motor and R11, not the other way around.
Here is how you can help me. Help spread the word: I will repair anyone's control board that is inoperative for the above stated reasons for approximately $30.00 US, plus shipping. (this offer is for the 3000, 4000 and 5000 series Neptunes with the through hole main control board only, not the surface mount board. I have no machine to test the surface mount board in.) For the $30 I will replace the 4 triacs with MAC97A8s and replace R11 with a 3.9K 1W 5% carbon film resistor. Turn time should be in the neighborhood of 1 business day + shipping time. I will ship per the customers instruction. I do not have wax motors yet, but I could obtain them if the demand is high enough for me to buy them in quantity, then I might be able to do that too. I have already repaired 10 of these boards for a friend. Door and water valve problems. It works. I will test the boards before the are returned, and I will guarantee the repair. E-mail me " Roy" at firstname.lastname@example.org for particulars. Please use "Maytag Neptune" in the subject line, or you may get sent to the E-Mail junk bin.
I am not an appliance repairman, I am an engineering consultant that does root cause failure analysis. I researched this problem for a friend that is an appliance repairman. I then started repairing some boards for him and subsequently also for a local appliance store. I am also interested in the motor control board problem. I don't have enough boards yet to come to a conclusion
One thing that has come up, I thought I addressed in the first e-mail, but I guess not well enough. The hot water valve (Triac at Q17), the cold water valve (Triac at Q9) and the Timer motor (Q3) are all subject to the same failure. That is why I recommended changing all 4 of them with the MAC97A8 600 volt version of that triac.
If you have hot water, but not cold, (or visa versa) swap the leads to the valves. If you now have cold water, but not hot (or visa versa) the problem is probably Q17 or Q9. There will be no visible signs of failure (as with the failure of Q6 (R11 burning)). but replacing the triacs will probably fix the problem. If this does not fix the problem, the problem is a wire. (probability the problem is the triacs has been 100% so far)
I have another one for you on the Maytag Neptune control board.
As everyone knows, if you plug the wires in backwards to K1 on the control board when you put the control board back in after repairing the machine, you won't have any water. Well, it makes sense, and has just been confirmed that, if the house power outlet the machine is plugged into, is wired backward you won't get any water either.
For all those that have just moved, and now their Maytag Neptune will not fill with water.... Check to make sure that the outlet you have the machine plugged into is wired correctly. There is a tool specifically designed to test for this (and open grounds etc) very inexpensive. The tool has 3 or 4 groups of 3 LED's.( Tenma GFCI/Polarity AC Outlet Tester ) You can obtain one from any good hardware store. You plug it in to the outlet in question and it gives you green, (good) yellow (Not so good) or red (Dangerous: Bad ground/no ground). Most AC things don't care if neutral and Hot are swapped or if there is a ground wire, but the Neptune does. It's a safety thing.
Herman Roy Goetjen
A section of the printed circuit was burnt/corroded and had actually melted a bit of the plastic holder.....a short was created there :eek keeping the fill valve energized.
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