I have a pyramid PS-26-KX PSU. This unit was accidently shorted across the DC plugs. I have replaced 2 of the 4 2n33055 power transistors, 3 of them tested bad, but due to someone's prior work, one of them was not making connection and therefor was still good. I only have 3 transistors connected at this time, as radioshack only have 2 in stock. I have removed the 4th completly and isolated the wires for it so they do not short to anything/each other. I also fixed some bad solder joints on the circuit board.
But of cource when I turn the unit on. I get the blinking red light and the buzzer going off. I have removed the TIP41C, it tested good so I put it bad in. All resistors in section RB of the schematic are good. The TYN416 SCR tests good. To the best I can tell with an analog test meter, the 16V zener diode is good as well. There are also no shorts in capacitor bank CX, with all power transistors removed, I do get 20v out of the rectifier.
Im almost at my ends with this unit. I do notice that looking at the section DA on the schematic it shows a total of 4 1n4002 diodes. However on my circuit board that are only two, can someone PLEASE take a photo of the circuit board if they have one of these units and post it for a reference. It is possible the someone worked on this after it was shorted, but he cannot tell me what if anything he did to it as far as removing/changing stuff.
thank you,
KC5TDG
bolwire@cableone.net
But of cource when I turn the unit on. I get the blinking red light and the buzzer going off. I have removed the TIP41C, it tested good so I put it bad in. All resistors in section RB of the schematic are good. The TYN416 SCR tests good. To the best I can tell with an analog test meter, the 16V zener diode is good as well. There are also no shorts in capacitor bank CX, with all power transistors removed, I do get 20v out of the rectifier.
Im almost at my ends with this unit. I do notice that looking at the section DA on the schematic it shows a total of 4 1n4002 diodes. However on my circuit board that are only two, can someone PLEASE take a photo of the circuit board if they have one of these units and post it for a reference. It is possible the someone worked on this after it was shorted, but he cannot tell me what if anything he did to it as far as removing/changing stuff.
thank you,
KC5TDG
bolwire@cableone.net