Dual-Output Adjustable Linear Regulated Power Supply problem

[tkellymd]

I am brand new to the electronics world. I have set up a home station for working on small scale electronics, i.e. soldering stating, antistatic mat and strap, etc.. I have read some basic electronics books and decided to attempt my first small project, assembling a Dual-Output Adjustable Linear Regulated Power Supply from Jameco.

I of course screwed it up. I switched the positive and negative regulators and turned the unit on. The LED comes on but I get crazy voltage signals on the DMI when I test. I did remove the regulators and put them in the correct positions but get the same result. I assume I fried the regulators.

Can I fix this problem by installing new regulators or have I fried the entire thing?

Thanks in advance,

Todd

 

[albert22]

Is very difficult to give you an answer without seeing the schematic. Or at least what are the numbers of the regulators.
If your power supply is low current it may be designed around the LM317 / LM337. It may have power transistors to handle more current.
You can check the circuit around the regulators with an ohmmeter. Measure the resistances for a change of value. Diodes for open or short circuit and the transistors for open or shorted junctions.
Once everything checks ok, replace the regulators and it will probably work ok.
You will get more help from the forum if you post the schematics. Also try to be more specific about the failure. "Crazy voltages" does not give a clear picture.
Good luck

 

[BradtheRad]

Assuming you installed a diode bridge (or 4 separate diodes), you should test each separately, in case any were exposed to high current.

Also test your transformer. Make sure it gives the expected volt and amp level at all wires.

Consider assembling the supply without the regulator IC's. Verify proper polarity. Verify no component heats up too much.

Then hook up only the positive regulator IC, and get it working properly. Then hook up the negative regulator.

 

[ads_ee]

This is probably the supply the OP bought.

https://www.jameco.com/Jameco/Products/ProdDS/20626%20Manual%20Revision%203.pdf

 

[alexan_e]

This is probably the supply the OP bought.

https://www.jameco.com/Jameco/Products/ProdDS/20626%20Manual%20Revision%203.pdf

What a design, a symmetric power supply where a center tapped transformer is included but used like a single output transformer leaving the center tap unconnected :shock: