I have a question about zenear diodes if I may. I downloaded this schematic and set it up in Eagle freeware. Upon testing I only get +15vdc instead of +15vdc and -15vdc. Is my second zenear diode in the right way or is it backwards Question mark
is not working for some reason. Will a zenear diode work with a negative voltage is my real question that I have been unable to look into and find info with Google.

 

Zenear (zener) diodes conduct as normal diodes in the forward direction (anode to cathode current flow) and exhibit their zener voltage in the reverse direction (cathode to anode current flow).

Your zener connections on the schematic look correct.

What is SL1?
If that represents a center-tapped transformer output, the center-tap should go to gnd.

 

Zenear (zener) diodes conduct as normal diodes in the forward direction (anode to cathode current flow) and exhibit their zener voltage in the reverse direction (cathode to anode current flow).

Your zener connections on the schematic look correct.

What is SL1?
If that represents a center-tapped transformer output, the center-tap should go to gnd.

SL1 pin three is GND

 

How should the front of my brd look as I get with 15 0 15 ACV this result.
Pin 3 GND
Pin 2 15ACV
Pin 1 15ACV
Outputs +19.9DCV & -19.8DCV
All others check at +15.3DCV
Is my brd wrong as GND shoud connect to - of bridge.
15.0 times 1.414 = 21.21 volts so 19.8 is not far off.

 

The 21.21V is reduced about 1V by the diode voltage drop in the rectifier bridge.
GND is not the - of the rectifier bridge. The - of the rectifier bridge is the un-regulated -19.8V.

 

Is my brd wrong as GND shoud connect to - of bridge.

That is wrong.
Gnd should be connected to the center-tap of the transformer.

 

Thank you for all replies. I will study what you said and try try again. Redesign the brd again after I study what you all stated. Best Kevin