Hi,
I am working on an appliance in which one of the cables decided to desolder itself. Inside the appliance there are three power supplies:
- 24V 600W LCM600Q-T-4-A connected to peltier elements
- 12V 160W RPS-160-12 connected to logic board and pumps
- 5V PSU connected to logic board (probably not involved in my issue, just listed for completeness)
The cable that decided to desolder itself was connecting the negative rails of the 24V PSU to the negative rails of the 12V PSU. See also the blue-highlighted wire in attached minimalistic schematic. Without both PSUs' negative outputs tied together the appliance fails to read the temperature of the peltier elements, so the logic board seems to require this.
I assumed that the wire connecting the PSUs' negative outputs was intended to ensure that the logic can trust that the negative on each PSU is the same. From what I understand this should be the "star" ground point with the "star" being very simple here since it is only one line.
When temporarily re-attaching the cable all is good with the appliance turned on and idling. In idle state the logic and the pumps (the motors in the schematic) on the 12V 160W PSU are running. However, once the peltier elements (powered by the 24V 600W PSU) are switched on, there is a current passing through the wire connecting the two PSUs. Current should be significant since the wire itself is becoming warm to the touch.
Is it expected that a significant amount of current is passing through that wire?
Any idea what could be playing up and how I could fix it?
Regards
PelzigesOhr