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@Justme You could be right. It depends on the purpose of C4 to some extent. It could be considered as a filter capacitor to earth separated only by the rectifier diodes from mains and, as the X-rated capacitor is supposed to fail short, it should fail open (Y-rated). On the other hand it could be considered as a part of the reservoir capacitor dealing with the higher frequencies of the load, in which case it doesn't need to be Y-rated. If it were on the mains side of the rectifier, between line and earth, then it must be y-rated.
@Hammdist You should be able to design a simple constant current driver with little more than one transistor and a couple of resistors. It doesn't have to be that accurate (10% spread should be more than adequate). Logic level via resistor into base, current defining resistor in emitter, LED column to collector.
There are more characters there than just "S2" and "M". It looks as if it could be "2MS2" and "GSM" but it's faint. Would you please try for a better photograph?
One hundred GIGA Henry? Do you mean micro or milli Henry? Please edit your circuit diagrams with the correct unit. Or is that the error that's causing Spice to misbehave?
Why do you think that reversing the fan will improve the heat distribution? Have you tried measuring the temperature in different parts of the oven at the same time and found significant differences? The air paths in the oven have probably been designed for unidirectional flow, transferring the heat uniformly from the elements to the interior. Reversing the flow may well cause hot spots where air does not flow backwards properly.
If you are driving the MOSFET from a low level logic signal then you should look for transistors described as "logic level". They are specifically designed to switch reliably with the sort of logic levels most common micros put out.
@Colin I think in his particular case we are talking about inverted logic. 1 becomes 0, 0 becomes 1 and AND becomes OR. Feeding 8 1s into an AND gate has exactly the same logic as feeding 8 0s into an OR gate except the output signal is inverted.
Have you considered redesigning the circuit? Put the string of LEDs between the +48V and the source and a resistor between the drain and 0V. Insert a resistor in series with R1 to limit the voltage on the gate. You've now got a variable constant current drive and you need to do the sums based on the max and min currents you want through the LED.
One of the main failure mechanisms for a lot of electronic equipment is the power surge when it's switched on. This applies for everything from light bulbs to computers. Often the stresses are at their greatest for the first few mains cycles as filaments heat up, smoothing capacitors charge up etc (it's often called "inrush current"). You say that you switch the deck off, but leave it's power supply permanently powered, so the output of the power supply would be subjected to said inrush current every time you use the desk. So yes, it could have worn out.
