newbie needs help with +/-15v psu

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#21
BobEllis said:

Anything on the order of 1-3K or so ought to work fine.
Click to expand...
I've got 2x 4.7k but that should work as well right?

Ive gotten the board to show the same no matter how it turns now.. a good start i suppose. I get +15V and - 4,6V no matter if the pcb is connected or not.
Will it be safe to stick in my bass and see if a load will do the trick or could I damage it if somethings wrong?
Thanks
 
#22
anatech said:
Hi Nikolaj,
I still think something odd is happening with your ground (common).

What are your AC voltages going into the PCB?
What rectified DC voltages do you get from your ground (common) on the PCB, before the regulators?

These will help come to a solution.

-Chris
Click to expand...

Ehm forgive my ignorance but by ac voltage going into the pcb do you mean before or after the transformer? on the entrance to the regulator?
and im not sure I understand what u mean by rectified dc voltages before the regulator?
Man this is hard though its simple.. damn 🙂

edit:
the ground(common) on the transformer output is the same ground throughout the whole amp.. thats ok right?
 
#23
Do not connect your preamp board to the supply until you have it ironed out.

You either have a short or a bad solder joint/broken trace on your PCB. Have you built this on a PCB? Where did you get it?

Anatech is asking about the voltage after the transformer. The DC voltage is the voltage after the rectifiers, but before the regulators.
 
#24
BobEllis said:
Do not connect your preamp board to the supply until you have it ironed out.

You either have a short or a bad solder joint/broken trace on your PCB. Have you built this on a PCB? Where did you get it?

Anatech is asking about the voltage after the transformer. The DC voltage is the voltage after the rectifiers, but before the regulators.
Click to expand...

Yes I build my pcb myself... its long cobberlines throughout the "pcb" so its not point to point. Im not sure what the type is called.
I think im having trouble getting whats a rectifier and whats a regulator.. I have 1 round chip, with the numbers on top i mentioned before, that gets AC from the transformer and gives, hopefully, +/- 15V.. I put it in instead of the 4 diodes here
http://www.albertkreuzer.com/pics/el/pre/schem/psu01_sch.gif

The ground is the same as on the transformer in my circuit.
I dont think I have both a regulator and a rectifier... Or am I just getting tired?
Think Ill take a fresh look at things tomorrow. Thanks for the help anyway everybody..
 
#25
That's called a strip board - a time tested way of making a prototype. Be sure that you cut the strips where you needed to so that you don't get connections you don't want.

The round thing is a bridge rectifier. With a 15VAC transformer and some capacitance after that you should see +/- 20V or so. You can measure this across C1 and C2 - if C2 is low, check that it is oriented correctly.

The regulators (7815 and 7915) after that drop this to the 15V that you need for your preamp.
 
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