LH Research Power Supply Mighty Mite

[Archon]

Anyone have any info on how to get these to switch on. The rear panel
has a 25 pin D connector, I guess sense, fail, operate lines etc.
Powers on and fans run but no output.
Model No MightyMite MMA31 -1/115-230 (5V 200Amp 1000W)
TIA JC

 

[Franc Zabkar]

Anyone have any info on how to get these to switch on. The rear panel
has a 25 pin D connector, I guess sense, fail, operate lines etc.
Powers on and fans run but no output.
Model No MightyMite MMA31 -1/115-230 (5V 200Amp 1000W)
TIA JC

FWIW, the SuperMite SM24 LH Research PSU of the 1980s had a 9-pin
(3x3) Molex connector that incorporated the following signals:

- on/off (input)
- AC power fail (output)
- DC power OK (output)
- "I" monitor (output)
- hi margin
- lo margin
- +sense
- -sense

The on/off pin was switched to ground to shut down the PSU. The fan
ran continuously.

To get the SM24 to regulate properly, you needed to connect the sense
wires to their respective load points, or jumper them directly to the
supply's outputs.

The hi/lo margin pins could be left open.

I'm guessing that the on/off pin would be pulled up to a standby
voltage via a resistor.

- Franc Zabkar

 

[Archon]

FWIW, the SuperMite SM24 LH Research PSU of the 1980s had a 9-pin
(3x3) Molex connector that incorporated the following signals:

- on/off (input)
- AC power fail (output)
- DC power OK (output)
- "I" monitor (output)
- hi margin
- lo margin
- +sense
- -sense

The on/off pin was switched to ground to shut down the PSU. The fan
ran continuously.

To get the SM24 to regulate properly, you needed to connect the sense
wires to their respective load points, or jumper them directly to the
supply's outputs.

The hi/lo margin pins could be left open.

I'm guessing that the on/off pin would be pulled up to a standby
voltage via a resistor.

- Franc Zabkar

Hi Franc,

Thanks for the reply, I don't think I'm going to get far by trial and
error. LH research seems to be Pioneer Magnetics, a completely useless
website with a very high opinion of themselves and no tech
support/documentation at all.

JC

 

[Franc Zabkar]

I don't think I'm going to get far by trial and
error. LH research seems to be Pioneer Magnetics, a completely useless
website with a very high opinion of themselves and no tech
support/documentation at all.

JC

You could determine which pins are the sense lines by measuring their
resistance (~100 ohms ?) to each of the +5V and Ground outputs.

The on/off pin would probably be sitting at Vstandby (+24V ?)

The AC Power Fail pin may identify itself if you rejumper your AC
input plug for 240VAC, assuming your local supply is 110VAC.

- Franc Zabkar