Guess I have to admit my ignorance here.
My little breadboard /w/ power supply (+5v@1A), adj(+15v@.5A), adj(-15v@.5A), is broke !
http://www.mpja.com/prodinfo.asp?number=17710+TE
Used it yesterday, been working fine, etc. Got up this morning, had (0v) on the adj (+15v) meter.
Oh boy ! I get to fix it !.Is really a simple looking board. Has LM317T voltage regulator for the +15v, LM337 for -15v (-15v is still working fine), the LM 317T had input voltage (approx 20v) but no output, no adj, not a problem, run down to radio shack, purchase a new one, replace= zilch.
Long story short, messing around, I happened notice I had the hot wire run to the breadboard, pulled it off, voltage shot up to +18v on the meter. I must've had it shorted , but how? worked fine last night, hadn't done anything since, anyway, now I got 18v instead of 15v,
"AND" the adj pot doesn't do anything to adjust it.
OK, I had originally thought about taking the pot out of the circuit and replacing it with a fixed resistor, that way I'll have a fancy pot to use on the breadboard (install terminals), now I'll just go ahead and put a resistor in that cuts voltage down to 12v.
Problem, during my figuring to find proper value of resistor (came to 14.4M). I had it sitting there running at 12v, put my little peizo buzzer on it to try it, and the voltage dropped to 8.5v, buzzer doesn't work.
So, I have no constant voltage.
I have looked and prodded around everything, looked high and low on the net for knowledge, schematics, am finally "lost".
I'm thinking about buying a similar power supply ($6.00) and just replacing it (is a little bit better),
http://www.mpja.com/prodinfo.asp?number=17721+PS
but, this one is just too simple a circuit to give up on.
So, am appealing to you guys for some knowledge, etc.....
The LM317T has voltage on all the pins, similar to the LM337, both circuits are right there together looking like twins, and yet, I can't find the cause.
And, there are a couple of small transistors (STS9014) that play a roll, connected to the "in" and "Adj" pins.
If I have to I'll have to go out there and get really into drawing the circuit out.
Hoping that someone can give me a quick fix instead of getting bogged down, etc, etc.
Thanks guys..
Oxbo
My little breadboard /w/ power supply (+5v@1A), adj(+15v@.5A), adj(-15v@.5A), is broke !
http://www.mpja.com/prodinfo.asp?number=17710+TE
Used it yesterday, been working fine, etc. Got up this morning, had (0v) on the adj (+15v) meter.
Oh boy ! I get to fix it !.Is really a simple looking board. Has LM317T voltage regulator for the +15v, LM337 for -15v (-15v is still working fine), the LM 317T had input voltage (approx 20v) but no output, no adj, not a problem, run down to radio shack, purchase a new one, replace= zilch.
Long story short, messing around, I happened notice I had the hot wire run to the breadboard, pulled it off, voltage shot up to +18v on the meter. I must've had it shorted , but how? worked fine last night, hadn't done anything since, anyway, now I got 18v instead of 15v,
"AND" the adj pot doesn't do anything to adjust it.
OK, I had originally thought about taking the pot out of the circuit and replacing it with a fixed resistor, that way I'll have a fancy pot to use on the breadboard (install terminals), now I'll just go ahead and put a resistor in that cuts voltage down to 12v.
Problem, during my figuring to find proper value of resistor (came to 14.4M). I had it sitting there running at 12v, put my little peizo buzzer on it to try it, and the voltage dropped to 8.5v, buzzer doesn't work.
So, I have no constant voltage.
I have looked and prodded around everything, looked high and low on the net for knowledge, schematics, am finally "lost".
I'm thinking about buying a similar power supply ($6.00) and just replacing it (is a little bit better),
http://www.mpja.com/prodinfo.asp?number=17721+PS
but, this one is just too simple a circuit to give up on.
So, am appealing to you guys for some knowledge, etc.....
The LM317T has voltage on all the pins, similar to the LM337, both circuits are right there together looking like twins, and yet, I can't find the cause.
And, there are a couple of small transistors (STS9014) that play a roll, connected to the "in" and "Adj" pins.
If I have to I'll have to go out there and get really into drawing the circuit out.
Hoping that someone can give me a quick fix instead of getting bogged down, etc, etc.
Thanks guys..
Oxbo