Lambda LFS-40-12 power supply question

[Ignoramus16375]

I have a Lambda LFS-40-12 power supply that I want to use for my son's
toy railroad. His hobby transformer failed. I pulled this LFS-40-12
from old equipment.

Here's the catalog

http://www.lambdapower.com/ftp/catalog/lfs_fall92.pdf

I am having trouble getting 12V out of it. I think that terminals S+
and S- and power supply and R+ and R- are remote sensing terminals. I
thought that by shorting R+ to R- I would get voltage between S+ and
S-, but no such luck.

Any ideas? Is it bad? I checked some voltages, there is reliable 160V
DC right after the DC rectifier, on the inputs of big DC
capacitors. After that, it becomes kind of murky.

i

 

[Dan Hollands]

I have a Lambda LFS-40-12 power supply that I want to use for my son's
toy railroad. His hobby transformer failed. I pulled this LFS-40-12
from old equipment.

Here's the catalog

http://www.lambdapower.com/ftp/catalog/lfs_fall92.pdf

I am having trouble getting 12V out of it. I think that terminals S+
and S- and power supply and R+ and R- are remote sensing terminals. I
thought that by shorting R+ to R- I would get voltage between S+ and
S-, but no such luck.

Any ideas? Is it bad? I checked some voltages, there is reliable 160V
DC right after the DC rectifier, on the inputs of big DC
capacitors. After that, it becomes kind of murky.

i
--

Leave R+ and R- open circuit

Connect S+ to Output + and S- to Output minus

The output voltage should be on the output terminals


Dan Hollands
1120 S Creek Dr
Webster NY 14580
585-872-2606
[email protected]
www.QuickScoreRace.com

 

[John Popelish]

I have a Lambda LFS-40-12 power supply that I want to use for my son's
toy railroad. His hobby transformer failed. I pulled this LFS-40-12
from old equipment.

Here's the catalog

http://www.lambdapower.com/ftp/catalog/lfs_fall92.pdf

I am having trouble getting 12V out of it. I think that terminals S+
and S- and power supply and R+ and R- are remote sensing terminals. I
thought that by shorting R+ to R- I would get voltage between S+ and
S-, but no such luck.

Any ideas? Is it bad? I checked some voltages, there is reliable 160V
DC right after the DC rectifier, on the inputs of big DC
capacitors. After that, it becomes kind of murky.

Try with nothing connected to the S and R terminals. They are usually
set up to function reasonably with no connections if you don't need
the remote sensing and turn off functions.

 

[Ignoramus16375]

Leave R+ and R- open circuit

Connect S+ to Output + and S- to Output minus

The output voltage should be on the output terminals

Thanks, Dan and John, no, there is no output with nothing connected to
S+/- and R+/-. There is some voltage AC or DC in various places of
this board when under power, however.

i

 

[Ignoramus16375]

I used another power supply by Digital (one of those $1,000+ surplus
supplies), it works okay, but I am very curious about the Lambda
supply. It shows some signs of life, and yet no output.

By the way, I have some interesting 30V power supplies (a couple amps,
plug into a tube socket), and a few by Power One: 24V power supply, 15
v power supplies, 12V, etc. The Power One ones are rated for about 6
amps. Very sturdily made, regulated, multiple input voltage, blah
blah. 5 or so lbs each. I could sell them, after testing of course.

i

Thanks, Dan and John, no, there is no output with nothing connected to
S+/- and R+/-. There is some voltage AC or DC in various places of
this board when under power, however.

i

--

 

[Rene Tschaggelar]

I have a Lambda LFS-40-12 power supply that I want to use for my son's
toy railroad. His hobby transformer failed. I pulled this LFS-40-12
from old equipment.

Here's the catalog

http://www.lambdapower.com/ftp/catalog/lfs_fall92.pdf

I am having trouble getting 12V out of it. I think that terminals S+
and S- and power supply and R+ and R- are remote sensing terminals. I
thought that by shorting R+ to R- I would get voltage between S+ and
S-, but no such luck.

Any ideas? Is it bad? I checked some voltages, there is reliable 160V
DC right after the DC rectifier, on the inputs of big DC
capacitors. After that, it becomes kind of murky.

usually, the sense lines require to be connected
to the output, meaning r+ to s+ and r- to s-.

Finally, there might be an output off switch somewhere.

Rene

 

[Meindert Sprang]

usually, the sense lines require to be connected
to the output, meaning r+ to s+ and r- to s-.

But the sense lines are usually alreade connected internally via small
resistors to make the unit operational when no sensing is needed. What is
more likeky to happen is that these supplies need a minimum load to operate
properly. I have seen that with many off-the-shelf supplies. If you measure
them withtout load, the voltage seems to jump up and down and sometimes you
can hear the supply make a very slow ticking noise while at each tick, the
voltage jumps to maximum.

Simply connect a small lightbulb across the terminals to provide a small
load so the supply can start regulating.

Meindert

 

[scada]

Leave R+ and R- open circuit

Connect S+ to Output + and S- to Output minus

The output voltage should be on the output terminals


Dan Hollands
1120 S Creek Dr
Webster NY 14580
585-872-2606
[email protected]
www.QuickScoreRace.com

Also many Lamda's have a "OV" adj, often mistaken for zero volts adj, it is
actually an overvoltage crowbar. If set all the way down, you won't get much
of an output!

 

[sparkman61]

Lamda LFS-40-12 power supply

I realize that this is a very old post. However, I happen to have two of these power supplies that were used in some old equipment that work fine. The FG terminal is connected to the S- and the TM2 (-) terminals. The S+ terminal is connected to the TM1(+) terminal.