To original question:
0 volts across a capacitor is usually bad. Resistors do not usually short. Voltage drop across resistor should be less than the watt rating of the package. With some experience you can guess the watt rating of a resistor by size and technology. power=(v^2)/R .
Semiconductors in a class AB amp, usually Vce < 1/3 the available rail voltage. With reduced rail voltage of a amp on a AC current limiter (light bulb) use the actual rail voltage difference, not the nominal. Output transistors, 1/2. Vce<1v is bad except relay or lamp drivers. Note tester results of transistors is at 2 volts and does not predict the word "good" at rail voltage. Vbe should be 0.6 v or =0.6 v. Except for lamp or relay drivers that can go into shutoff mode, low Vbe. Diodes should be 0.6 v if forwards biased, negative bias can go up to the rail. Op amps should have both inputs and the output at same DC voltage, except ones used to drive lamps or relays.
DO not use 2 hands to probe voltage across parts. >25 v across the heart can stop it. Use a clip lead on one end and the probe on the other end. Wear no metal (jewelry) on hands wrists or neck, 1 v at high current can burn your flesh to charcoal. Wear safety glasses, parts can explode.
This amp does not have the intended DC output of the DC300 series etc so is not totally unsuitable for driving speakers. Could be useful if a bit noisy at high gain with 0 input (between cuts of source). 339 or 349 op amp could perhaps be fiddled with something else with some thought. Quieter parts are available with the 741 style pinout.
0 volts across a capacitor is usually bad. Resistors do not usually short. Voltage drop across resistor should be less than the watt rating of the package. With some experience you can guess the watt rating of a resistor by size and technology. power=(v^2)/R .
Semiconductors in a class AB amp, usually Vce < 1/3 the available rail voltage. With reduced rail voltage of a amp on a AC current limiter (light bulb) use the actual rail voltage difference, not the nominal. Output transistors, 1/2. Vce<1v is bad except relay or lamp drivers. Note tester results of transistors is at 2 volts and does not predict the word "good" at rail voltage. Vbe should be 0.6 v or =0.6 v. Except for lamp or relay drivers that can go into shutoff mode, low Vbe. Diodes should be 0.6 v if forwards biased, negative bias can go up to the rail. Op amps should have both inputs and the output at same DC voltage, except ones used to drive lamps or relays.
DO not use 2 hands to probe voltage across parts. >25 v across the heart can stop it. Use a clip lead on one end and the probe on the other end. Wear no metal (jewelry) on hands wrists or neck, 1 v at high current can burn your flesh to charcoal. Wear safety glasses, parts can explode.
This amp does not have the intended DC output of the DC300 series etc so is not totally unsuitable for driving speakers. Could be useful if a bit noisy at high gain with 0 input (between cuts of source). 339 or 349 op amp could perhaps be fiddled with something else with some thought. Quieter parts are available with the 741 style pinout.
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