DC Voltage Supply Problem

[dengberg]

I had a quick question about a dc voltage supply I have been working with. When I turn it on and hook it up to the oscilloscope, the oscilloscope value stays at 0 regardless of the dc voltage I set. To double check this, I also tested the supply with a multimeter. When I did this, the correct voltage read for a split second, but the value on the multimeter quickly diminished to 0. I checked the multimeter on a battery and it is fully functional. Is there a problem with my voltage supply?

 

[Reloadron]

If when coupling to the scope the signal was DC coupled to the vertical of the scope and if the meter used was set to measure DC volts then I would assume there is no output from the supply you are measuring. Depending on the make / model of the supply and it has and is using current limiting if the pot (current limit) is set all the way down then it would not be unusual to see what you are seeing. However, if this si a standard DC power supply I would assume a supply problem. Since the meter was checked against a battery and read fine I would suspect the power supply to be faulty also.

Ron

 

[Sceadwian]

Details about the DC supply you're using would help.

 

[Reloadron]

Yeah, per Sceadwian, you aren't giving much information?

Ron

 

[dengberg]

I am using a Hewlett Packard E3610A DC Power Supply

 

[Reloadron]

E3610A 30W Power Supply, 8V, 3A or 15V, 2A

OK and to answer the questions I asked? Like where is the current pot set? Turn the current pot full CW or at least away from fully CCW and see if the voltage out can be measured. Have you read the user manual?

What does the front panel of the instrument meter read?

Turn-On Checkout Procedure

The following checkout procedure describes the use of the
front panel controls and indicators illustrated in Figure 2 and
ensures that the supply is operational:

a. Push LINE button to ON.
b. Set RANGE push button to desired range.
c. Turn VOLTAGE control fully counter clockwise to ensure
that output decreases to 0 Vdc than fully clockwise to
ensure that output voltage increases to the maximum output
voltage.
d. While depressing CC SET push button, turn the CURRENT
control fully counter clockwise and than fully clockwise
to ensure that the current limit value can be set from
zero to maximum rated value.

Ron

 

[dengberg]

I did read the user manual when I encountered these problems. Unfortunately, the steps described in it did not seem to work. The current pot is set to full CW and I set the voltage to 2.5Vdc. When I read the voltage out with the multimeter, I got the same diminishing voltage as before. As far as what the front panel reads, it only says the output voltage (2.5V) and the current (0A). The current does not change when I hook up any oscilloscope probes or multimeter probes to the voltage out, but as far as I know it should not change much for these anyway.

 

[Reloadron]

Connecting a scope probe or DMM will not draw any current you would notice. If you can setup the Vout on the instrument front panel with the current pot turned up and as soon as you try to measure it the supply Vout drops (folds over) my guess is something is very wrong with the supply. That assumes as you mentioned, you are working from the manual. Actually if you place a short across the thing with the current pot partially turned up you should read the current on the instrument.

Ron

 

[Sceadwian]

Test the power supply on something like an LED or small lightbulb.