Power supply problem...help

[Dennis]

Hi,

I have a Buchler PS, 1000/250VDC @ 25/250mA.

There is a meter for volts and amps.
When I turn the voltage knob I get a readout
on both ranges, however there is
no output. When I switch to the current
meter, I get a maximum output on the voltage
meter, and the dial doen not function.

Would this be a bad regulator circuit?

It is an older supply, so there are no
3-terminal regulators on board. Any
help would be appreciated.

TIA,

Dennis

 

[John Woodgate]

I read in sci.electronics.design that Dennis <Dennis@charter.net> wrote
(in <vqsvnvgto5i8f9@corp.supernews.com&gt about 'Power supply
problem...help', on Sun, 9 Nov 2003:

Hi,

I have a Buchler PS, 1000/250VDC @ 25/250mA.

There is a meter for volts and amps.
When I turn the voltage knob I get a readout
on both ranges, however there is
no output.

Do you mean that you get a reading on the current meter when there is no
load on the output? If so, that suggests that there is an internal
short-circuit that is drawing the current you see on the current meter.

If you mean that there are two voltage ranges, and you get indications
on both, then that is normal operation.

When I switch to the current
meter,

I suspect that you have a switch labelled 'VOLTAGE' and 'CURRENT', which
actually changes the mode of operation of the supply from constant-
voltage to constant current.

I get a maximum output on the voltage
meter, and the dial doen not function.

That is correct operation for a constant-current power supply. The
voltage automatically goes to maximum so that the supply can drive the
set current into as high a load resistance as possible.

Would this be a bad regulator circuit?

Not necessarily: the fault, if there is one, could well be between the
regulator output and the output terminals.

There may be nothing wrong with the supply except a failed output fuse.

--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!

 

[Dennis]

In article <JbtngYCOppr$Ewti@jmwa.demon.co.uk>, jmw@jmwa.demon.contraspam.yuk
says...

I read in sci.electronics.design that Dennis <Dennis@charter.net> wrote
(in <vqsvnvgto5i8f9@corp.supernews.com&gt about 'Power supply
problem...help', on Sun, 9 Nov 2003:
Hi,

I have a Buchler PS, 1000/250VDC @ 25/250mA.

There is a meter for volts and amps.
When I turn the voltage knob I get a readout
on both ranges, however there is
no output.

Do you mean that you get a reading on the current meter when there is no
load on the output? If so, that suggests that there is an internal
short-circuit that is drawing the current you see on the current meter.

If you mean that there are two voltage ranges, and you get indications
on both, then that is normal operation.

When I switch to the current
meter,

I suspect that you have a switch labelled 'VOLTAGE' and 'CURRENT', which
actually changes the mode of operation of the supply from constant-
voltage to constant current.

I get a maximum output on the voltage
meter, and the dial doen not function.

That is correct operation for a constant-current power supply. The
voltage automatically goes to maximum so that the supply can drive the
set current into as high a load resistance as possible.

Would this be a bad regulator circuit?

Not necessarily: the fault, if there is one, could well be between the
regulator output and the output terminals.

There may be nothing wrong with the supply except a failed output fuse.
--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!

thanks for the help. When I flip the "volts/current regulation" switch
to current the voltmeter pegs at max, and no response from the current
meter. At any rate there is no output at the output terminals.

Dennis

 

[John Woodgate]

I read in sci.electronics.design that Dennis <Dennis@charter.net> wrote
(in <vqtapf4hduu363@corp.supernews.com&gt about 'Power supply
problem...help', on Sun, 9 Nov 2003:

thanks for the help. When I flip the "volts/current regulation" switch
to current the voltmeter pegs at max, and no response from the current
meter. At any rate there is no output at the output terminals.

What happens if you connect a resistor across the output terminals? I
suggest a 60 W lamp in a cardboard box, in case the power supply
severely overloads it and it explodes. The lamp may or may not light up
but you should get a reading on the current meter.

Have you found any failed fuse yet?
--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!

 

[Dennis]

In article <WmewfcAAX0r$Ew8I@jmwa.demon.co.uk>, jmw@jmwa.demon.contraspam.yuk
says...

I read in sci.electronics.design that Dennis <Dennis@charter.net> wrote
(in <vqtapf4hduu363@corp.supernews.com&gt about 'Power supply
problem...help', on Sun, 9 Nov 2003:

thanks for the help. When I flip the "volts/current regulation" switch
to current the voltmeter pegs at max, and no response from the current
meter. At any rate there is no output at the output terminals.

What happens if you connect a resistor across the output terminals? I
suggest a 60 W lamp in a cardboard box, in case the power supply
severely overloads it and it explodes. The lamp may or may not light up
but you should get a reading on the current meter.

Have you found any failed fuse yet?
--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!

Yep, it was only a blown, front panel fuse.