Hi, I'm new to electronics but I found a Xantrex XHR 20-50 at a swap meet for what I think was a great deal. It's a little banged up but it seems to function fine. Anyway, I can't seem to figure out how to adjust the current. The knob doesn't seem to do anything and being new to electronics I don't quite understand the manual. Right now if I set the voltage the current will automatically adjust to meet needs of whatever I'm powering but I am looking for how to set the current manually. Thanks.

Here is link to manual:
http://www.programmablepower.com/dc-power-supply/XHR/downloads/XHR_Operation_Manual_TM-XROP-01XN.pdf

 

Normally you need to short the leads then adjust your max current.

 

Normally you need to short the leads then adjust your max current.

So I can change the max the current by putting it in standby holding the QVP/VI button and adjusting the max current but as far a I know that just limits it from going over a certain current. When I see videos on youtube of people who have these they can change the current however they want. Please forgive my ignorance I'm very new to electronics.

 

Have you tried following the instructions on pages 37 and 38 of the owner's manual? You do not really need a current shunt as to see how it works:
1. Ensure that the front panel power switch is set to OFF.
2. Turn the voltage and current controls on the front panel fully counter-clockwise.
3. Turn the voltage control one (1) or two (2) turns clockwise.
4. Connect a DC shunt across the output terminals on the rear panel. (Just short the output skip to #7)
5. Connect a DVM across the DC shunt. The DC shunt-DVM combination must be rated better than 0.5% accuracy.
6. Turn the power switch to ON.
7. Slowly turn the current control clockwise. The current mode LED will turn on.
8. Compare the DVM reading with the front panel ammeter reading using I=V/R where V is the DVM reading and R is the DC shunt resistance. The control range is from zero to the maximum rated output for the power supply model.
9. Turn the power switch to OFF. 10. Disconnect the DVM and the shunt.

This is pretty much what spinaker is getting at. When you see the current increase what you see is what you get as to the limited current.

Ron

 

Have you tried following the instructions on pages 37 and 38 of the owner's manual? You do not really need a current shunt as to see how it works:
1. Ensure that the front panel power switch is set to OFF.
2. Turn the voltage and current controls on the front panel fully counter-clockwise.
3. Turn the voltage control one (1) or two (2) turns clockwise.
4. Connect a DC shunt across the output terminals on the rear panel. (Just short the output skip to #7)
5. Connect a DVM across the DC shunt. The DC shunt-DVM combination must be rated better than 0.5% accuracy.
6. Turn the power switch to ON.
7. Slowly turn the current control clockwise. The current mode LED will turn on.
8. Compare the DVM reading with the front panel ammeter reading using I=V/R where V is the DVM reading and R is the DC shunt resistance. The control range is from zero to the maximum rated output for the power supply model.
9. Turn the power switch to OFF. 10. Disconnect the DVM and the shunt.

This is pretty much what spinaker is getting at. When you see the current increase what you see is what you get as to the limited current.

Ron

I will try this, thanks.

 

I do not know your power supply.

Apparently on your supply you do not need to short the leads. Page 58 very clearly states the procedure for setting current.

 

Sorry page 53.

 

Sorry page 53.

Ok, I'm gonna try it an get back to you.

 

So I followed the steps on pg 53, and I believe I was able to set the current limit.

 

adjusting the max current but as far a I know that just limits it from going over a certain current.

Yes, exactly. That is what the current control is. just think of it as a rev limiter on an engine. Until the setting is reached, it has no effect on the output. Current limit is very handy for protecting circuitry. For instance, if you expect the max current to be 100mA, and you set it at that. The power supply will regulate the voltage ok until the 100mA is reached then the voltage will drop to keep the current at the 100mA. If there is a faulty part or design, it can help keep the smoke in as the current cannot rise to many amps and blow things up.
I often start repairs with the current limit turned down and if that is ok, then the current can be turned up for a full test.