LH Research Power SUpply problem

[birdofplay]

About 15 yrs ago I was scrapping out an obsolete piece of mainframe
type peripheral. It has a huge LH research power supply that a nabbed.
It sat for all these years until now.

I've hooked it up with the intention of using it's output for
powering some Lipo chargers.

I Hook up the Sense taps, Plug it in and Outputs seem OK.
Attach a Duratrax ICE charger, just as a test, start a charge cycle and
Right after the battery check and as soon as the actual charge starts
Peeeew ... the Volts drop dramatically. ???

It does the same with or without the sense wires hooked up.

This is an Old MightyMite with a DB15 on the back.
MMA74-e2186/115-230
5v 150A - no even using it. yeah you read it right !
12v 10A - this one is the problem
5.4v 5A - not using
12v 5a - not using


Any ideas as how to proceed ?

[Dan Baldwin]

You may have one of 2 problems;

You say that you are hooking your charger up to the sense terminals. Are you jumpering the sense and the output terminals. Some power supplies have the sense terminals hooked to the output terminals through small resistors. You can hook the load up to the output terminals, then hook separate wires from the sense terminals directly to the load after the wires to make up for voltage loss in the wires to the load. You can also just hook the load directly up to the output terminals, and either jumper the output terminals to the sense terminals, or leave them open. The sense terminals will be fed by the on board resistors.

It sounds like this power supply is basically a 5 volt power supply that also has 12 volts, but it expects the main load to be on the 5 volts. You may be able to get it to work with a load on the 5 volt supply, like some of the PC power supplies. You can start with a 1 amp or so load(automotive tail light bulb, or 5 ohm 10 watt resistor), and see if that does it.

Dan

[birdofplay]

I have the outputs for the 12v strapped to their sense taps.
I tried it strapped and unstrapped - no go either way.

Ah, I hadnt considered the 5V side interaction !

I will try that next. I have lots of of power resisters laying about.
I'll cobble up a load and have at it !

I had not intended to use the 5V side and since it provides SO MUCH current
I have it taped off so I wouldn't accidentally Short out those monster terminals !

The whole thing would make an excellent BOAT ANCHOR ! :-)
But free is free so I gotta try to use it, ya know

Thanks, Dan

more L8r

L8r:

Um ??? no go !

I put 5 Ohms 15W across the 5 volt lugs.

I wonder about that DB15 on the back.

You dont think this thing has to be interfaced, do you ?

Then again, interfaced with WHAT?

I'm about ready to take it down to the boat !

PIC +V2 & +S shorted -V & -S shorted

5 ohms across 5v lugs

[Ron W3FJW]

looks like a linear supply so it might be easier just to gut it and use a 723 regulator and pass transistors for high current.

[birdofplay]

I've been hesitant to even loook inside yet as
I've not been able to find and Manuals/ docs et al for this particular model !

It's pretty DENSE packed in that blue metal chassis with a monster fan at one end too.

Whoda thunk a PS needed to be that complicated.

Thanks for the advise , guys.

C U L8r

Bob