GW instek GPP-4323 no load display off

[Veketti]

Dear All,

Could someone who has these GW Instek DC power supplies check whether nothing connected to the terminals it shows load? Mine shows on every channel >1mA, whether this is normal? It is brand new power supply and second already as the previous one had faulty channel 1...

Thank you in advance.

[Hexley]

The readback accuracy for current is specified as +/- (0.3% of reading + 10 mA). So an error of +1.2 mA is well within spec.

Pity that Instek does not publish the calibration method so owners could adjust things.

FWIW, my unit has ~ 1mA indicated at no load on all channels except one -- Channel 4 indicates exactly 0 mA with no load. Luck of the draw.

[Hydron]

It is actually possible to calibrate it using some undocumented SCPI commands, it's a bit of a pain though and really needs to be done with an automated setup (there are many calibration points). I never found time to write the script to do so (not my strong suit) and my lab is packed away right now so can't help much sorry, but it can be done - I played around enough to confirm that.

[mawyatt]

Pity that Instek does not publish the calibration method so owners could adjust things.

FWIW, my unit has ~ 1mA indicated at no load on all channels except one -- Channel 4 indicates exactly 0 mA with no load. Luck of the draw.

Ours behaves similar.

Agree GW needs to make the self Cal available to users without the need to dredge thru a bunch of SCPI programmed routines/scripts.

Best,

[Hexley]

It is actually possible to calibrate it using some undocumented SCPI commands, it's a bit of a pain though and really needs to be done with an automated setup (there are many calibration points). I never found time to write the script to do so (not my strong suit) and my lab is packed away right now so can't help much sorry, but it can be done - I played around enough to confirm that.

That's pretty tantalizing, Hydron.
Do you remember off the top of your head how you went about discovering the undocumented SCPI commands? That might give a head start to anyone who wanted to re-discover the trail you blazed...

[przemo1268]

Hi!
Does anyone have more information regarding the SCPI commands and method to calibrate the GPP-4323? The only sensible source of information I've been able to obtain so far is the service manual for the SPD3000X power supply (in the attachment), but that's a different manufacturer and a different device. I can write the calibration software, but to do that, I need to be sure of the entire procedure.

[mawyatt]

See below.

https://www.eevblog.com/forum/projects/firmware-mod-for-gwinstek-gpp-series-lab-bench-power-supply

Best,