I have a Samsung electric dryer, dve45n5300v/a3, that has no DC power to the front display board. I've checked all circuits and all of the safety elements (thermal cutoff fuse, thermistors, door open switch, broken belt switch) are in working order and completing their respective circuits. I have 120V from each power leg to neutral, and 240V between the legs. On main control board, I have 120V appearing on both the heat and motor relays, relative to pin 1 (brown / neutral) of the power plug, but no DC voltage out to the sub display / front panel, which should be 12V DC between pin 5 (white) and pin 6 (red) and 5V DC between pin 5 (white) and pin 4 (pink). I've tried 3 main control boards and 2 sub display boards with same issue. Only things NOT tested are the steam valves (irrelevant) and front touch panel that plugs into the front sub display; almost stumped but suspecting a possible motor issue. Here are the questions:
- What should the AC voltage read on the main control board 3 pin power plug (brown/blue/black) between pin 1 (brown/neutral) and pin 3 (black wire / motor switch check circuit) as I'm getting 2.5v AC there which seems old.
- Would a bad motor potentially cause the entire dryer to seem "dead" - i.e. no power to front panel?
- Motor ohms out as follows: Pins 3 to 4, 1.9 ohms (vs. 2.88 ohm target), Pins 4 to 5 1.9 ohms (vs 3.5 ohms target). Centrifugal switch looks good inside and out with clean contacts and working switch.
Longer version of the story:
Dryer initially has a "stuck" relay to the motor, so it would tumble without stopping unless door was opened but dryer otherwise worked fine. Ordered, received and installed a new main control board (noticing bent metal frame and finger prints all over the clear epoxy protecting the PCB) and dryer was "dead" upon reassembly. Removed control board and as I was putting it back in the (damaged) Samsung box that it came in, noticed an RMA form where someone had already returned this board as being bad via a different distributor than I used! So, tested the original board (one with stuck relay), confirmed short across motor relay, tapped relay with handle of screwdriver, and it opened! Reinstalled original circuit board - dryer still dead. Contacted distributor, they overnighted another main control board and I purchased a sub display also, just in case. Installed new control board and new sub display at same time - same symptoms - dead. Testing concluded no DC power out of connector from main display board to sub display, every single wire in wiring harness tests good, only suspect measurement is the 2.5VAC on pin 3 of the power connector to main control board which is a return from the centrifugal switch on the motor. I've attached a wiring diagram and details of the main control board for reference.