thanks. I understand now why in this situation only 50% of the power is usable. It also got me thinking along these lines.SkyNorth wrote: When connecting the two secondary windings together , one is the source , the other is the load. Each has its own internal resistance.........When this happens you get a voltage divider,........with equal voltage drops across each. , this means the power transfer is split evenly between the two.
"In a normal situation , when a transformer is operating with its rated load on the secondary, a high percentage of the available power is transferred to the load because the internal resistance of the secondary windings is very small when compared to the resistance of the load."
Kilrah wrote: Best is to use 2 probes in differential mode to measure waveforms across components.
This was very helpful. thanks again. Being the impatient type I did not wait for the isolation xformer to arrive and used the tip you guys gave me. I was able to probe the circuit. It was very cool to see the bridge rectifier working properly. I could see the positive half on ch 1, the negative half on ch2, and the computation of the measurement between the points with the math function. If I wanted to I could see them all on the screen at the same time in different colors Was able to determine that the switcher was attempting to start and then shutting down. Started focusing on the output side of things and removed about 4 fast switching diodes for test. one of them was shorted. ( -15v line ) put it back together using a diode that isnt utilized in this configuration ( +12v) and got the power supply workingSkyNorth wrote:To use two probes , keep them referenced to circuit ground , and measure both sides of the part in question ,one probe on each side. Use the scopes "subtract" function, to subtract the lower probe from the upper probe , and this will give you the reading across the part in question.
Still gotta wait on some parts before I can button it up because I damaged the input filtering inductor and the bridge in my initial (short circuit) testing. Jumpered out the input filtering inductor and used a bridge that would work but is physically too large to fit to continue troubleshooting.
Showmaster: It is under the math function that I found the 'A-B' setting for the scope. I havent used the math function much. Initially investigated the 'fft' feature a little, mainly because it got such negative reviews online. Didnt even go very deep into it so cant comment on the fft feature personally.