Electronics > Beginners
Manson DPD-3030 PS - modifications possible?
MarvinTheMartian:
Hi all,
I recently purchased a Manson DPD-3030 power supply (see Shock's thread for photos - https://www.eevblog.com/forum/reviews/photos-manson-dpd-3030-triple-output-power-supply/msg664001/#msg664001 ).
This PS has single turn pots (very touchy and difficult to adjust settings accurately) and does not have a 'Load On/Off' switch.
Could someone (Shock perhaps has already done this?) advise me on a couple of questions please?
* There seems to be plenty of room inside to replace the one turn pots for ten turn pots - are there any traps to doing this or is it simply replace the old with the new?
* To put in Load On/Off switches for each output (or all outputs?). For individual switches - is it as simple as putting a switch in between the output jacks and the wires connected to them or are there issues in doing this? For one switch to control them all - how would I achieve that?
I'm pretty new to working out how circuits work so I am unsure if what I am proposing is a good idea or it will just ruin my new PS! :scared:
Thanks everyone. :-/O
ElektronikLabor:
--- Quote from: MarvinTheMartian on March 04, 2016, 01:45:51 am ---1. There seems to be plenty of room inside to replace the one turn pots for ten turn pots - are there any traps to doing this or is it simply replace the old with the new?
--- End quote ---
I don't see any traps if the pot has the right resistance value and mechanicaly fits into the holes
--- Quote from: MarvinTheMartian on March 04, 2016, 01:45:51 am ---2. To put in Load On/Off switches for each output (or all outputs?). For individual switches - is it as simple as putting a switch in between the output jacks and the wires connected to them or are there issues in doing this? For one switch to control them all - how would I achieve that?
--- End quote ---
If a PSU has an On/Off switch its nearly allways for all outputs together. I could imagine it's because it's cheaper :-//
I would also fit the switch between the wire and output jack, because that should not affect the voltage reading of the display.
But at the moment I can hardly imagine a reason why to switch the channels separately.
To switch all channels together you need a two positional switch with three isolated inputs which can handle the current
MarvinTheMartian:
Thanks Medvedev. I might go ahead with that. I remember watching one of Dave's videos where he says it is good to have the load switch instead of just the power switch as the output would be unstable initially and may blow your circuit. :palm: So the motto is don't connect your circuit if you use the power switch to avoid damage! :scared:
Really appreciate the great information in Dave's videos and everyone on the forum (which I've only just started using). :-+
Shock:
No haven't modified mine yet as I've had other things keeping me busy. When it comes to switching the load on and off, a few things about the behavior of the power supply dictates how you would need to approach this.
Firstly I think that the DPD-3030 would benefit from a simple switch on each channel shorting the outputs to allow you to set the constant current. Obviously when you automate this you would need to measure for voltage spikes/surges so you could observe if switching with a circuit load connected could damage the circuit. But in order not to present a shorted or a high current path to the circuits positive and negative rails the switch would need isolate the shorted path from the circuit at the same time. If you can do this cleanly this solves two of the problems.
The other issue is the DPD-3030 works in both single channel mode but also in parallel and series (doubling the current supply or the voltage supply). You would need to consider this before implementing any switching system to either prevent damage or functionality problems which is why I was looking at the possibility at doing this elsewhere or working out all the possible scenarios at least beforehand.
Swapping out the pots seems simple as it's just up to determining if drop in replacements are suitable for size, value, rating (important) and pins. A 10 turn pot may be an overkill perhaps 5 may be more suitable.
MarvinTheMartian:
Thanks for the info Shock :)
--- Quote from: Shock on March 05, 2016, 03:35:06 am ---Firstly I think that the DPD-3030 would benefit from a simple switch on each channel shorting the outputs to allow you to set the constant current.
--- End quote ---
I understand what you're saying but when you set the current using the pots doesn't this set the maximum current delivery anyway (as if you had shorted the outputs)?
[I'm not that experienced yet |O]
--- Quote from: Shock on March 05, 2016, 03:35:06 am ---Obviously when you automate this you would need to measure for voltage spikes/surges so you could observe if switching with a circuit load connected could damage the circuit. But in order not to present a shorted or a high current path to the circuits positive and negative rails the switch would need isolate the shorted path from the circuit at the same time. If you can do this cleanly this solves two of the problems.
--- End quote ---
Thanks for the tips. :D
--- Quote from: Shock on March 05, 2016, 03:35:06 am ---The other issue is the DPD-3030 works in both single channel mode but also in parallel and series (doubling the current supply or the voltage supply). You would need to consider this before implementing any switching system to either prevent damage or functionality problems which is why I was looking at the possibility at doing this elsewhere or working out all the possible scenarios at least beforehand.
Swapping out the pots seems simple as it's just up to determining if drop in replacements are suitable for size, value, rating (important) and pins. A 10 turn pot may be an overkill perhaps 5 may be more suitable.
--- End quote ---
Yes, I had considered the doubling of the voltage/current needed to be taken into account for the switch specs. I was also thinking that I may be swapping one hassle for another by using 10 turn pots (Dave had mentioned using these in one of his videos) but I wasn't aware there were also 5 turn pots - this sounds like a good middle ground - thanks!
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