PM200-13C VR2 question

Aug 05, 2008 3 Replies
S

I just bought a PM200-13C & was adjusting the output voltage. In a careless fashion, I turned the one pot I saw without marking it, hoping that the lacquer would break so I could see where the pot was originally set. Unfortunately, the lacquer broke off the pot completely & the output voltage stayed put. I then saw the pot behind it, which adjusts the output quite nicely. Now I want to set the first pot back, but can't figure out what its function is. I figured it might be the overvoltage protection, but the ps trips out at 19.2V regardless of pot setting. Over current maybe? Any ideas? Datasheet for ps is here:

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I know I was being careless, please don't grill me, I'm just looking for a little help.



Thanks, Steve


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F

On Tue, 5 Aug 2008 16:58:50 -0700 (PDT), sck0006 put finger to keyboard and composed:

Other than overcurrent, perhaps the PSU can sense an AC Power Fail condition, eg a brown out. Years ago I worked on minicomputer grade switchmode PSUs that had adjustable AC power fail detection. I notice that connector P3 has a "PFD" pin (PFD = Power Fail Detection). I'd monitor that pin while tweaking the pot.

See

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Otherwise I'd do some quick circuit tracing.

- Franc Zabkar

Please remove one \'i\' from my address when replying by email.
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S

Good idea, I wouldn't have even thought of that. That'll also be easier than figuring out if it is for overcurrent, it's rated at 15v ~13A, I don't have any variable load in that range, probably just use a fet & op amp.

If I get back to it soon I'll post my findings.

Steve

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S

You were right, it adjusts the level at which the PFD pin goes low. Thanks for the help, I would've been hunting for ages.

Thanks, Steve

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