Problem with my Tekpower PSU:

https://tekpower.us/downloadable/download/sample/sample_id/1/

Here's a teardown on YouTube:

https://youtu.be/Nfe28vGW6Ik

Problem is it's developed a fault where the current meter always reads 0
when in constant-voltage mode. Everything else seems to work fine and
it's putting out the right voltages, current limit works fine, when load
current exceeds the set point it current limits OK and shows the correct
value. Drop back and the display reads 0, again.

Here's the schematic (PDF), logic board only, unfortunately but the
power board seems to be working OK.

https://www.eevblog.com/forum/testgear/tekpower-tp3005t-variable-linear-dc-power-supply/?action=dlattach;attach=249613

Overcurrent detection seems to work by voltages IS- and IS+ coming in
from the off-board current shunt and sent to pin 19 of the PIC, which I
believe is a comparator-interrupt pin, and that seems to work ok, and
the voltages out of that op-amp and across the current shunt look OK.

Constant current mode seems to work by using TL082 section "N18BB" as a
comparator open-loop, and then the loop is closed around back from the
ADJ line that goes off-board to the power regulator board, and the
current-set DAC output from the PIC, comparing the two inputs against
each other.

Constant-voltage mode works similarly the voltage-set DAC value from the
PIC is compared against the voltage at the output and a line is asserted
when they match. The output voltage in CV mode looks OK.

It's not clear to me though how what the current actually is, in
constant-voltage mode, is sensed by the PIC, as I don't immediately see
a pin on it where the current-shunt voltage is being read by the uP, so
it's hard for me to know where to look for the problem as nothing
obvious is amiss, and continuity on all the connections between the
boards to the PCBs seems OK.