Lambda Power supply hookup

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riggler

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Joined
Jan 24, 2006
Messages
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Location
Pennsylvania, USA
Hi all,

I have a Lambda LXS-C-15-R power supply. On the front of it, there is a sticker that says "BYPASS R-20". I can't find a manual for it. It has -S,-V,0V,+V, and +S connections.

It's a 15V bipolar regulated supply. I am guessing that the S connections are for some form of sensing. All I want to do is use this to power a reverb unit. Does anyone know how I should hook this up?

If I measure across -V to +V I am getting 30V. If I measure from 0V to -V, I get about -1V which immediately starts dropping in voltage down to like -.002V. If I measure from 0V to +V, I get about .5V which again drops really fast and keeps dropping.

These tests are done unloaded.

When I got it, there was a funky looking diode with the anode on -S and cathode on -V. I put that diode back in place and the behavior is essentially the same. I am hoping someone here has used these and has documentation or knows what to do!

My gut is telling me to just strap -S to -V and +S to +V.
 
As a rule you connect -s to -v and+s to +v. That should be all you need to do to power your reverb unit.

The remote sensing is intended to ensure the voltage at the end of the cable is the required voltage despite the drop in the cables.

Cheers

Ian
 
Okay, I strapped as suggested. -V and -S strapped, +V and +S strapped

Now I am only seeing 11V between +V and -V... Tests between +V and 0, -V and 0 are same behavior as before.

I wonder if I need to put a real load on it in order to test. I have two of these supplies, and both are behaving the same way.
 
You should be measuring dc but I am sure you know that. Here is a picture of you psu. As stated before v+ and s+ connect together, v- and S- connect together.  I would hook up a load and test again...
 

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Yep, I am measuring DC.

The power supply you show is exactly like mine. And that is how I am strapping as well.
I don't have any ground connection from the wall right now. I tested and have continuity between the circuit ground output point and the chassis.

Am I supposed to connect wall socket ground to the circuit ground point? Right now wall socket ground goes nowhere.

Anyway Pucho, if you measure from 0V to +V and then -V, what are you reading?

I will try testing loaded. I will turn the voltage trimmer down and hook it up to the reverb (will look for some power resistors instead for testing if I can find something) and bring it up and see what happens.

On the front of your unit, on the upper left corner, do you have a sticker that says "Bypass R-20"? I opened mine up and indeed R20 is jumpered over with a wire lead...
 
Am I a moron here....? Don't answer that. But is this really a bipolar supply? Cause the catalog for these supplies lists the LXS-C-15-R as a "Single Output Fixed Voltage" supply.

And now with the thing loaded with my reverb, I am seeing fluctuating around 7V between 0V and +V, and about 12V between -V and +V.

Sure LOOKS like a bipolar supply, but maybe it is not!
 
riggler said:
... between 0V ....
Single rail floating supply, adjustable in range between 12V and 15V (and terminal 5 is case ground, not 0V reference voltage).
If you decide, your 0V reference voltage will be at the V- terminal, the V+ terminal will measure +12...+15V.
If you decide, your 0V reference voltage will be at the V+ terminal, the V- terminal will measure -12...-15V.

If you want a bipolar +/-12...15V supply, get a 2nd.floating maybe Lambda PSU and hook them up in series.
(Tie V- of the pos.rail 1st.PSU to V+ of the neg.rail 2nd.PSU, giving your 0V reference voltage at this V-/V+junction. With respect to this reference voltage you'll get +12...+15V at the V+terminal at the 1st.PSU and -12...-15V at the V- terminal of the 2nd.PSU.)
Which reverb unit need this amount of current ?
 
This is what I figured now. My reverb is a Multitrack Dual Equalized Spring Reverb. It doesn't require nearly the amount of current these supplies can provide. I built a supply for this reverb, but it's a little noisy. My friend gave me these Lambda supplies and said they were very quiet. We were both thinking they were bipolar +15 / -15, but they are not!

I am going to revisit my original supply and add some better filtering.
 

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