rail voltage

[mike49504]

hi i have a question i work on amps but i know there is alot more i need to know I habe the basic knowledge on fixing them but im wondering how do u test the rail voltage like with a multi-meter what points do u put the test leads to get the rail voltage of an amp i wanna learn more about theese things any help would greatly be appeicated

 

[jol50]

Go right here, Perry is nice enough to post on here as well.

http://www.bcae1.com/repairtutorialcdinfo.htm

Think there is a part that shows the layout of a typical amp, check that out so you can recognize the various parts of an amp like power supply, outputs, rectifiers, etc. Scroll down to the links.

 

[I Am An Idiot]

The easiest place to find it is on the rectifier diodes. They will ususlly be a 3 legged device located between the power supply transistors and the output transistors. They will be labeled on the board with a Dxxx, xxx being a number. There are 2 rectifier diodes, one positive and the other is negative. You can also find rail voltage on the output transistors.

 

[jol50]

Not hard once you recognize an amp, for example sony likes to make their amps in circles for explod amps. Most amps have PS at one end with the round transformer and fets, and the amplifier itself the other half of the amp. Most class AB the non-bridging speaker terminals are the common as some the transformer is glued and hard to get at center tap, but the tap is really where you should check from. Most outputs the center leg is rail but not always, but at idle with only power hooked up that will be the only high power on any output leg. Some amps have jumpers to the outputs you can check.