Arlec's PB4UHA 4 way Power Board with USB power

The above unit replaces this:

Plain old powerboard with Brilliant Smart BL20925 wifi switches (with brains replaced to Tasmota) controlling 24VAC plugpacs which activate garden watering solinoid valves.

Brilliant Smart's BL20925 Wifi switch with current measuring.

The original part of the system, which is a couple of years old now, features 4 BL20925 switches controlling the solenoid valves. Most of this has been replaced by the newer Arlec PB4UHA 4 way power board with a brain transplant needless to say.

Disassembly and Brain Transplant

While the computer module and related parts operate at the very low and safe DC voltage 3.3 volts and the programmer runs off USB power, the power board itself runs on mains voltage, which in Australia is nominally 230 volts +10%/-6%. This voltage can KILL you. Do not ignore this warning. Do not attempt to operate or otherwise manipulate an opened unit. This unit  is relatively cheap, if stuff goes wrong hardware-wise just call it as a fail and throw it in the bin.

The first hurdle to getting in to this thing cleanly is the triangular screw heads.

These require special tooling which was supplied by the local electronics store.

In the following view we can see the Tuya module controlling everything.

And with some very careful desoldering we remove the module from the main board. Pay particular attention to the delecate tracks on the bottom side as these are very easily ripped up (trust me). This is where the adept hand of a skilled technician is envaluable. Sugical precision is required (something which is lacking here at electricbrain).