Quote:
Originally Posted by Chris K
We're getting a bit outside my abilities and I hope as the hands on person, I'm providing accurate information regarding the problem solving. I understand solid state stuff even less than tube stuff! If we're talking about relatively low DC voltage circuits affecting one another, I guess I should be much more specific about providing exact values. A few years of measuring and evaluating voltages in the hundreds, and seeing 380V on a circuit that is supposed to have 400V on it thinking 380V isn't an issue, I think I better tighten my error bars. In reality, the +20V line is closer to 22V and the -75V is more like -74.5V (again, these aren't exact...I'm at work and I don't have it in front of me!)
Bottom line...I don't want to keep anyone up late at night chewing and contemplating this trying to problem solve it if I'm not providing accurate data and facts. I'll recheck the voltages this evening and provide accurate information out to 2 decimal places.
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You should not worry about keeping anyone up late. You have provided accurate facts. It is just that sometime the HP engineers were trying to be too clever (my opinion). When troubleshooting, the power supply often provides clues to what is wrong and right now we are only attempting to understand what is wrong. The understanding of the power supply sheds new light and the fact the +20v is spot on and the -6.3v is a bit low to me is not yet a red warning.
Let's review the symtoms again:
"...Have a very low power clean 12.5MHz sine wave. The frequency doesn't change whatever I do to the wheel and the output level has no effect on the amplitude. The meter still doesn't move into the readable zone..."
To me this again is pointing to the output hybrid amplifier. I think we should step back and reflect how to confirm this.