Need Help Rebuilding a Power Supply

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PTL60

Member
2002-02-01 6:30 pm
I have a power supply that I would like to rebuild, not redesign. It's a simple one that I feel can be improved with replacing some or all the parts using the same PC board. This is a 24VDC output supply at 500ma. These are the parts:

LM317T regulator
(5) 1N4002 diodes
(1) 120 ohm resistor
(2) 2.2K ohm resistors
(1) 2200uf/50V cap
(1) 47uf/50V cap
(1) 10uf/50V cap
(4) #103 ceramic caps
(1) Transformer that measures 30VAC at secondary. The primary and secondary of the transformer have only 2 wires at each end.

Whoever originally built this was very sloppy. The circuit board has flux all over it and really needs to be cleaned up,and a lot of bad solder joints as well.

I don't have a schematic, so I was wondering if I could possibly use some better quality parts.
 
Circuit

This type of circuit layout is something like Walt Jung i think. DOn't qoute me on this( remember reading somewhere). The circuit layout can be found somewhere in welborne labs website. You might have to look around. To upgrade this ps, you could start with Linear Technology Device i think lt1086(check this out at questlink.com) this replaces the lm317. Better regulater than lm317 and lower noise but at a cost. You could change the diodes to Ultra-Fast type or you could put 10-22nf capacitors parrallel to each diode. AS usually you could change the 2200uf to something bigger according to your budget but not that nessecary. FOr the #103 ceramic caps i think they are used to bypass bigger electros like the 2200 uf. If this is so use 100nf foil capacitor but avoid ceramic used polyester or polyprops. Resistor you could change to 1% metal film type if they aren't already. Best of luck then on upgrading this but do check out the welborne labs side lots of detail on this type of circuit and check the lt1086 model could be wrong.
 

PTL60

Member
2002-02-01 6:30 pm
NickC,

Thanks for the info. I've been looking at this PC board from this power supply and it's in pretty bad shape, so I'm probably not going to bother with it and go with something new altogether.

I would like to reveal this power supply in case anyone may be interested.

This power supply is the Creek Audio OBH-2, which is used with the Creek OBH-11SE Headphone Amp. I was really surprised at how poorly made this was. I'm not saying that it's a poor design or choice of poor parts; It was put together very poorly and sloppy. There is flux all over the top and bottom of the circuit board and the solder joints are very poor and dirty. What was also surprising is that it just looked "old", even though it was purchased less than a year ago.
 
Sounds like a generic LM317 power supply; might try looking up the application notes at Linear Technology. Other than the
suggestions already given, there's not a whole lot that can be
done with it that the parts list suggests hasn't already been
done.

Walter Jung's Super Regulator is something else altogether and
is a far sight better in terms of regulation and low noise. There
is a modification that allows operation up to 24 volts. I'm using
a pair in my Hafler SE-100 preamp.
 

PTL60

Member
2002-02-01 6:30 pm
Well, I finally did it. I rebuilt the OBH-2 power supply and it's working great! I used the same circuit board and transformer, but I replaced all the components with fresh new ones including the LM317 regulator. I mounted the pc board and transformer in a new enclosure. So, now it's like brand new. No more flux and dirt on the pc board and good solid solder joints. I don't know if I'm imagining things, but my OBH-11SE headphone amp never sounded better. I guess it was worth it.
 
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