See you got 10V in-out for sure, then change Q1 too. Burned Zeners you found show that something went wrong at a point sometime.
That Q1 you put in could be problematic from previous use in other tests and regs? Now it does not draw any current. Zeners are OK still?
But you got an operating led. 1mV through 10 Ohm TP means 0.1mA. How it can operate the Vref's CCS to set 300V and light the LED? Fishy measurement. Is the sink getting warm?
Zener near trimmer measures continuity both poles, the other zener don't measure continuity both poles, have I to desolder the zeners to measure them well?
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Both zeners without continuity both poles.
What I have to do:
-Replace the zeners & check the current?
-Wait to new DN2540 & replace zeners & DN2540 to test the current?
What I have to do:
-Replace the zeners & check the current?
-Wait to new DN2540 & replace zeners & DN2540 to test the current?
To properly test a Zener we need a higher DC voltage source than its value, a protective resistor, then we measure if it meets its value. A little circuit in other words.
I would dummy up the reg load, wet the TP pads with some solder to be sure they conduct to the probes well at all times, and test it in isolation to the Itch for components, oscillation with the scope, different power source or grounding, such stuff. All those data up to now are contradictory. Once it conducts showing well on TP but does not trim CCS there is a bricked trimmer, then it shows 0.1mA but its Vref and led works and 300V voltage is set that needs over 2mA to work in itself and there is some warmth even, then some zeners seem burned but not sure, then some DN2540 changed but not sure of their condition etc. Still there was never smoke. Can't draw a conclusion. DN2540 are like JFETs and can be tested for IDSS by the way, expecting rough 150mA range. You did well to get some even for spares if those you already got will prove good. They are very useful with tubes in general. So gather some certain experimental data, and if there is a defect in parts it will stand out with exchanging. How it played music without ripple hum and sets to an output voltage its perplexing nonetheless. I would also try a different C1. I hope it isn't like the other one you had once that its belly was conductive to the extra pads.
I would dummy up the reg load, wet the TP pads with some solder to be sure they conduct to the probes well at all times, and test it in isolation to the Itch for components, oscillation with the scope, different power source or grounding, such stuff. All those data up to now are contradictory. Once it conducts showing well on TP but does not trim CCS there is a bricked trimmer, then it shows 0.1mA but its Vref and led works and 300V voltage is set that needs over 2mA to work in itself and there is some warmth even, then some zeners seem burned but not sure, then some DN2540 changed but not sure of their condition etc. Still there was never smoke. Can't draw a conclusion. DN2540 are like JFETs and can be tested for IDSS by the way, expecting rough 150mA range. You did well to get some even for spares if those you already got will prove good. They are very useful with tubes in general. So gather some certain experimental data, and if there is a defect in parts it will stand out with exchanging. How it played music without ripple hum and sets to an output voltage its perplexing nonetheless. I would also try a different C1. I hope it isn't like the other one you had once that its belly was conductive to the extra pads.
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Thanks again for support Salas, I will wait the new DN2450 to be sure and I will solder TP pads to be sure for conductivity. I keep the schematic how to test 12V zeners🙂
Followed in Power supplies forum Simplistic Mosfet HV shunt regulator
http://www.diyaudio.com/forums/power-supplies/134801-simplistic-mosfet-hv-shunt-regs-348.html
http://www.diyaudio.com/forums/power-supplies/134801-simplistic-mosfet-hv-shunt-regs-348.html
