The repair guide is for when the galvanic isolation has failed. This happens when more than 3.3volts comes from the hash board.
Before continuing with the following instructions, please ensure that your hash board and connection cable function correctly. Do not attempt to fix the tester if you’re not sure it is the cause of the problem!
Most of the time, the problem occurs because of the blown a fuse on the 3.3V power line. However, it may happen after connecting the hash board with a short in a power line.
You will need a fluke 17B+ multimeter for this repair. In addition, the hash board must be disconnected.
Set the multimeter to voltmeter mode. First, you must measure voltage between the is_GND and is_3V3 test points. Follow the images below.
The voltage must be around 3.3 volts. If the voltage on those points is ok, you need to proceed and check the F2 fuse.
If the voltage on the F2 is lower than 3 volts - the isolated power supply is faulty. This repair is a bit more complicated and requires experience. In that case, please get in touch with a professional for repairs.
Set the Fluke 17B+ multimeter to measure the resistance. Check the fuse like it’s shown in the picture below.
If its resistance is 0 ohm - the fuse is working fine. In that case, the cause of the problem might be the I\O hash board connection cable, the connection port, hash board, or other components. For further instructions, please contact a professional for repairs.
If F2 resistance is any other than 0 - the fuse is blown and needs to be replaced. Fuse is in 0402 case, 1 A. It can be purchased in most electronic stores. After replacing, ensure you solder it properly and perform all the measures again. After that, you can connect the hash board and check if the problem is fixed.