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Forum Index => Dryer Repair => Topic started by: tkerwinjr on February 20, 2019, 03:17:58 PM

Title: MED9800TQ0
Post by: tkerwinjr on February 20, 2019, 03:17:58 PM
hey guys i'm lost on this dryer. i have checked everything in this dryer and i cant seem to figure this one out. so you push the start button you hear the relay on board click and that's it. i have changed out the board first the motor and still same thing. i have 4.6 ohms at the p1-3 and p1-4. so per tech sheet change out board and nothing. even got a second board same thing , am i missing something? element good, thermal fuse good, door switch good belt switch good i'm lost please help. lol thanks in advance..
Title: Re: MED9800TQ0
Post by: manden on February 21, 2019, 06:20:05 AM
I cannot find a wiring diagram for your unit.
With luck the below manual for a MED9700 will be close or at least give you and idea how to proceed.
https://drive.google.com/file/d/0BzIiBNwRIV4NN0N3dG84WnhfNG8/view

I am not sure I understand part of your post.
Did you replace the motor as well as the board?

Unplug the unit and attach one meter lead Neutral at the power cord.
Now measure to the white on the door switch, should be 0 ohms.
Measure to the blue on the door switch, should be 0 ohms with the door closed.
keep the door closed (switch activated).
Measure to P1-3 and P1-2, both should be 0 ohms.
Measure to 5M at the motor, should be 0 ohms
Measure to one side of the belt switch. should be in the 1 to 2 ohm range.
This can vary depending on  the motor winding resistances.If each winding is 3 ohms then when measured in parallel it should give 1.5 ohms.
Measure to the light blue on the belt switch, should get the same motor winding resistance.
Measure to both sides of the thermal fuse, should see the motor resistance.
Measure to P1-4 should also be the motor resistance.

OK that is the motor wiring.
You may also want to check the individual main and start windings in the motor to be sure they are OK.

If all the above are OK.
Plug the unit in and measure from P1-3 to P1-4
You should see 120 volts.
It should drop to 0 volts when you start the unit.

Note use the lowest resistance scale/mode when doing the above.
Not that stupid continuity check mode on the meter as you do not know what the meter company thinks constitutes continuity.



Title: Re: MED9800TQ0
Post by: tkerwinjr on February 21, 2019, 08:13:32 AM
Ok I have checked everything here but the voltage at the p1-3 and p1-4 but had between 1-6 ohms there . Yes I have changed motor and control board twice now. I even carry the door switch and put it in just to see nothing. It almost seems like the board but two new ones and still same thing. Is it possible for a bad batch of boards? Thank you for the help!
Title: Re: MED9800TQ0
Post by: manden on February 21, 2019, 08:53:11 AM
" p1-3 and p1-4 but had between 1-6 ohms there", the manual does say to replace the board if you see this.

Yes it is possible that there is a bad batch of boards out there but then anything is possible.

Unfortunately this is a case where the schematic of the board would be useful but is not available.
I would think that P1-3 is just a door switch open/closed sensing line so a low resistance may indicate that the control electronics are bad.
But who knows it may go to one side of the motor relay contacts.
Trace it back to see where it goes.

I have not seen anything about a bad batch of boards but with a little luck someone else will jump in with more/better info.

Title: Re: MED9800TQ0
Post by: tkerwinjr on February 21, 2019, 09:19:12 AM
Thank you so much for the help. :cheers:
Title: Re: MED9800TQ0
Post by: dab147315 on February 21, 2019, 09:51:45 AM
I'll put up the tech sheet for his model.
Title: Re: MED9800TQ0
Post by: tkerwinjr on February 21, 2019, 10:02:25 AM
Thank you
Title: Re: MED9800TQ0
Post by: rkious1 on February 21, 2019, 05:23:27 PM
Put a jumper between P1-4 to P1-5 and see if it runs . This eliminates the electronic controls if it does not run. If it does not run then use you voltmeter and see where you lose the voltage . Sometimes wires , switches , and  ect  will show continuity but not carry  a load .   Good luck ! Also I always check the voltage at the terminal block when it is under a load for the same reason.

Ross