Try changing the filter capacitors, as I doubt they will do a good job after exceeding their WV.
Gajanan Phadte
Gajanan Phadte
I did change the caps with new ones along with the diodes. The transformer maker color-coded the primary leads but did not indicate polarity. Measuring with voltmeter only (a mistake) showed I had the right leads connected. There was no change. Also, I rechecked with the pc oscilliscope, this time hooking up the leads after energization, and a spark was seen. Apparently, I may not connect the leads to mains ground. SO the sine wave I saw was false. Moreover, the voltage reading was way to high.
So at least one leg saw somewhat less than 50v, so rectified would be somewhat less than 85v since the transformer was saturated, and the voltage drops on the various resistances. The caps were rated at 50v. But would a leaky cap pass AC if it is being blocked by the diodes? Would it be diode leakage current passing through the cap?
I did find a wiring problem that when remedied, diminished the buzz to 50% of what it was. Small dropping resistors, <1R in series with the primaries, are good to have, but are not enough to eliminate the buzz.
It is happening on the charging peaks obviously, since 10R drastically reduces the problem.
Now, instead of the mains fuse blowing, the positive leg on the amp blew after a minute of running, and now blows instantly. The amp has to be rebuilt now. Fortunately, all the transistors are inexpensive. May as well get all brand new recifier parts, too.
Many of the wires in this prototype are too long. I need to redesign the chassis because it is too short and not deep enough, it turns out. So with more room, and a more traditional layout, all the wires will be shorter which should diminish or eliminate this problem.
Which leads me to a definition question. A ground loop is a situation where currents of different parts of the entire system pass each other, creating oscillations and such. And another kind, or the same kind, sort of creates an antenna?
Thank you for your heads up on the caps.
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