PSU acting strange.

[juniorselector]

I built a PSU like the diagram attached with 7815 voltage rectifiers as IC 1 and 2 and feeding it 15V AC.

It's supposed to give me +/- 15 V. But it reads +15V and -21V on my meter.
When I turn off the power it continues to give me -21V. How can that be?

I connected it to an NTP 182-120 and it worked great. However, when I tried it on my Tore Seems F2000A it sounded very strange (I hope I didn't burn off the unit).

How do I fix this?

 

[Giggity]

7815 regs are for positive voltage, not negative.  You will need a 7915 on the negative rail.  Just a guess, the reg on the negative rail is cooked and passing the full, unregulated -21vdc rectified voltage.

 

[juniorselector]

That sounds like the answer! Thanks!

Do you think I caused damage to my Tore Seems EQ?

 

[juniorselector]

So it should be allright if I change the 7815 to a 7915?

 

[Giggity]

Probably will be fine just changing out the reg to a LM337.  I would check first though, just to be safe.

Honestly, I'm not familiar enough with your particular EQ to say one way or another.  Perhaps some one else will chime in and say.

 

[PRR]

Note that Positive and Negative regulator chips have DIFFERENT pin-outs.

You may have to bend your reg's legs "up" and jumper-around to the right holes on a PCB.

 

[Giggity]

While his PDF isn't clear (only shows component location, no schematic) what is clear is that the component location isn't a mirror image from one side to the other. Although this isn't 100% proof, I would guess that the PCB allows for the different pin out between the LM7815 and the LM7915.  A schematic would show one way or the other.

Probably will be fine just changing out the reg to a LM337.

Sorry. I meant to say here LM7915, NOT LM337

 

[juniorselector]

I changed it to 7915 today and got a perfect signal.

Thanks for the help.