GE Washer (WBB3300A0WW )potential control board issues

[mmbridges]

Hi all,

I have a GE wasging machine model (WBB3300A0WW ) that has recently started experiencing some apparent motor problems. When agitating or spinning the motor seems to move at a slower than normal speed and the clutch seems to be holding and releasing loudly in a cyclic manner. I disconnected the motor form the control board ( WH12X10176 ) and applied 120V directly between start wire winding terminals  (M6,M1) and high speed terminals (M7,M3) and motor spun perfectly. I reconnected the motor connector back up to control board, turned control knob to spin, pressed start and experienced the problem. I repeated this a couple of times and verified that when control board was bypassed problem disappeared.

In an attempt to diagnose the control board, I unscrewed the relay board so I could examine the traces on the back of the PCB and noticed no burnt or broken traces. I did noticed that after I pressed start, with the knob in the spin setting, I hear the relay's click, and the motor start to spin up, but 2 seconds later the relays click again and the problem reappears. I repeated this experiment and felt the top of each relay box and it seemed like all of them were clicking twice.

I looked at the large power relay model numbers, and found their spec sheets to locate the relay12V coil leads.  I wanted to see if voltage was being applied to the coils after the second click so I placed my multimeter on the two solder leads protruding from the back of the PCB associated with the relay coil. Sure enough when I press start I hear the relays click and I read 12VDC across the coil. After the second click there seems to be a transient in the voltage and it goes back to holding at 12VDC. I was thinking for some reason the control board might be removing 12V from the coils causing them to click while de-energizing but the presence of the 12V seems to negate that hypothesis.

OK now the real interesting observation. While doing these tests to see if 12VDC was being applied to all of the large relays there was a third click and the slow motor/loud cyclic clutch behavior stopped and the motor spun up to full spin cycle speed smoothly. Coil voltages were steady at 12VDC!

So here is my new hypothesis of the sequence of things:

1. start button pressed
2. 12V is applied to relay coils which close the normally open contacts and applies voltage to the motor
3. Motor starts to spin up normally
4. A second click occurs suggesting the relay contacts open back up while still being energized since 12VDC is still being applied
5. This new state with some of the relay conacts opened up (I can't tell which one's yet) results in less voltage being applied to the motor
6. This low motor voltage causes the slower speeds and the cyclic clutch events.
7. For some reason the relay contacts close back allowing full voltage to be applied to the motor and it spins up as normal.

So here are my questions:

1. Has anyone experienced this phenomenon before?
2. I know one solution is to buy a new control board and see if that fixes the problem but before I try that I want to know if anyone has ever done a control board diagnosis and repair?
3. Can anyone think of the cause of these intermittent relays contacts opening and closing? (Might this be a common failure mode of these relays where the coil is no longer able to hold the contacts closed under 12VDC?

I'll stop there for now.

Thanks folks!

Mike

 

 

 

 

[mmbridges]

After a bit more diagnostics I have determined that when the lo speed motor winding is powered that is when the anomaly occurs. I was able to look up the relay part numbers to get their pinouts then look at the large traces on the back of the PCB to reverse engineer a schematic. By probing the back of the pcb board during various points of the washing cycle I determined which relays were energized to put the motor into agitate vs spin and high speed vs low speed modes. Turns out that second relay click I was hearing was correctly being initiated by the control board to put the motor into low speed mode which is when the anomaly occurred. So previously when I bypassed the motor I was using the high speed motor winding which spun fine and why I assumed the motor was fine. However now I have verified the lo speed winding is the problem by repeating the control board bypass test but this time using the lo speed winding. I also tested spin and agitate modes.

 

So here is the new question. Does anyone know how the internal switches work in the motor? I know there is a centrifugal switch and understand that opens up the starter motor winding at a certain speed. But how does the internal the switch work that seems to be connected to the low and high speed motor windings?

Also does anyone have the GE motor 5KH61KW2516GS winding resistance specs? I want to see if the problem is the low speed windings has burnt out or if this internal switch associated with the low speed winding has malfunctioned? I have not found a spec sheet which typically lists winding resistance.

 

Thanks!

 

 

[mmbridges]

Ok finally fixed the problem. 

I took motor out and pried away four tabs that held the back housing cover onto the stator lamination stack. I tried prying the cover off to get access to the centrifugal switch to examine the contacts. No luck cuz rear motor bearing inner race was stuck onto shaft and the outer race was stuck into housing cover. I brought it to a co worker who is good at this stuff and he helped me get it off. Basically supporting the edge of housing on a ledge and hitting end of motor shaft with mallet popped the housing cover off. The bearing was still stuck on to shaft but had popped out of housing seat. Yayyyy!  Sure enough the centrifugal switch contacts were inside a plastic switch body with tabs. The switch body was easily pulled apart exposing extremely charred contacts. Very fine Emory cloth was used to clean off the char. After nice and clean we put it back together, hammered the housing back onto the bearing to seat it and folded tabs back down to secure housing. Put it back in tonight and problem solved! My buddy said contacts would probably chat back up over time since we did not polish contacts but I know what to do next time.

Before I took motor apart I ordered a used motor from eBay $99 just in case things didn't work out. I'll probably keep it just in case the fix does last or some other motor part breaks. I'll tell you what this sure beats buying a whole new washer and dryer to match!