Tuning a PS23023 power supply

[JacquesBBB]

Dear All,

On my power supply PS23023, the tracking is slightly off, as well as the max values
for the two channels. It seems to need a little bit of tuning.
On the boards (master and slave), there are three pots described also on the schematics :
https://www.velleman.eu/downloads/2/ps23023gbnlfresd.pdf

RP1 : 4.7 kohms
RP2 : 220 ohms
RP9 : 10 kohms

Can anyone tell me
what are the functions of these 3 pots. Which one will tune the max V, min V, and tracking balance ?

Thanks

Jacques

[Kevin.D]

Hi .
Rp2 will adjust your max Voltage range .

RP1 will adjust your max Current range .
Rp9  adjust's your input offset Voltage of the Current
Error amplifier . (so you'd use it to allow current set to 0)  .

None of these will make any difference to your tracking balance
in series mode (which doesn't really have to be ultra precise ) .
The precision of this is set by R100,R101 (fixed 47k voltge divider).
The centre of these two  should be exactly  (chan A+B)/2 when both channels are in series.
(these two simply divide the voltage of the combined channels in series
and feed it to 2N1 opamp via your two mode switches) .
 
If it has slight offset one resistor could have drifted out of spec.
If these are ok then your probably got a bad connection through one of the
2 mode switches contacts (check to see if voltage drop between R100/R200 junction and OP 2n1 inv input .
(note :- I think this should actually go to the non inv input and there is a mistake on this schematic you linked ,  it show's the slave channel opamp inputs reversed  but they should be as in  the master channel I would think)  .

[JacquesBBB]

Hi Kevin,

Your answer is really great !  Thanks a lot.

I have searched extensively on the net and was not able to find any information on this.

(note :- I think this should actually go to the non inv input and there is a mistake on this schematic you linked ,  it show's the slave channel opamp inputs reversed  but they should be as in  the master channel I would think)  .

You are  most probably right here. I  had the  same thought, and actually checked the connections on the two boards. They are exactly the same. So  the slave board opamp have  the same connections as the master, and the schematic is wrong.

I have not the power supply on hand here, but will test what you suggest in two weeks when I will go back to the house where  is my electronics workshop.

Thanks again,

Jacques

[pegase1985]

hi,

I got the same dual power supply and one of these relays is whisling (K2) on the left electronic card when i'm increasing the voltage (between ~ 12.2V and 15.8v ....)

do you have any ideas ?

i'm a newbie in electronics

Many thanks