Model Number: DV42H5200EP
Brand: Samsung
Age: 1-5 years

Hi,

I have a 2 1/2 year old Samsung Front-Loading Dryer (Model # DV42H5200EP) that has stopped heating. I tested the heating relay by probing both the blue and black wires (see attached schematic) on the heating relay individually between ground and measured 120VAC. I then measured the voltage difference between the blue and black wires at the relay with the dryer running on timer mode and measured 240VAC. The 240VAC indicated to me that the relay was not closing, so I inserted a temporary wire between the black and blue wires at the heater relay to bypass the relay and confirm that the heating assembly worked. When I ran the dryer with the bypass inserted at the heater relay, the heating coil lit up red almost instantly, so I know this works and is not the issue. I then tested the resistance of the thermistor by unplugging the dryer and disconnecting the harness from the control board and measured close to 10kΩ at at an ambient temperature between 23°C to 25°C which matched the resistance in Samsung's service manual.

This led me to then believe that the control board was the issue and I went and purchased the control board below:

https://www.repairclinic.com/PartDet...00669Y/3996510

Once the new control board arrived, I replaced the old control board with the new control board and still no heat. So, I again re-tested the heating relay and still see 240VAC between the blue and black wire, when the dryer is running. So this heater relay is still not closing either. I thought that the thermistor may be close to going, even though it tested fine previously, so I retested it and still measured 10kΩ. To completely rule out the thermistor, I then bypassed it using three different resistors (3.3kΩ, 10kΩ and 22kΩ) to represent different voltages going to the control board and measured the voltage difference across each while the dryer was running. The 3.3kΩ resistor measured approv. 1.3V, 10kΩ was 2.47V and the 22kΩ was 3.4V. However, none of those resistors were able to turn on the heater relay either.

Does anyone have a schematic for the Samsung controls for these dryers that they could send me or see something that I may have missed? I didn't think there was anything else that Samsung monitors to turn on the heating relay. The only other thought I had, was that the new control board is also faulty; however, I think this is very unlikely.

Here are some pictures of the dryer schematic in the service manual and how I bypassed the thermistor:

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