I chose the LS100 24V 4.5A model to test, afterwards I intend to use it to power some stepper motor drivers.
First impressions are that the unit is of good quality and was made in Vietnam where I guess labour is
cheap. There are very similar items on eBay in fact they look identical but are not made by TDK, I think
I might get one to compare the quality.
I liked the easily removable hexagonally punched cover which slides off once the screw
is removed. There is a threaded hole for a second screw but this was missing.
I adjusted the VDJ pot to 24.01 V no load. (the pot is quite sensitive to get exact) I don’t have any
resistive loads to properly test the current but I did have two old 12V car headlamps that were wired
in series which drew a measured current of 4.33A. Initial surge current was just over 6 Amps from
cold, voltage drop was 0.03V
Testing the Over Voltage Protection (OVP) by adjusting the VDJ pot the unit shutdown it's
output at 27.9V which was just over the specified voltage range of 27.6 - 32.4V, minimum adjustment
was 19.29V, input mains disconnection is required for at least 2 minutes for the OVP to reset.
This model has a seven terminal block of the barrier type, three for mains input L-N-E,
and two sets of screws for the output, on higher current models 25A+ it is recommended to use
both sets of terminals to spread the load
The internal fuse is vertically soldered to the board, I would have preferred to see an easily
replaceable fuse, however being a compact unit with the other upper side comonents also
vertically mounted there is little space, there are surface mount components on the underside
of the pcb
On reassembly after taking a look at the quality of the soldering which was good, I noticed the
bracket and neoprene boot holding the Q2 power Mosfet against the chassis. I have never seen this
arrangement before. I assume this would not get that hot to cause concern as the unit is rated at
86% efficient. The boot insulates the casing from the chassis but I would have preferred
to see the more usual through bolt with insulating washer.
With thanks to Alistair and Garden State