when testing these on an amp im working on,99% of them are around 6v FB and o/l RB
but i have a couple that are around 6v FB and 2.5v RB
does this indicate they are faulty or is this within normal perameters?
but i have a couple that are around 6v FB and 2.5v RB
does this indicate they are faulty or is this within normal perameters?
A normal silicon diode should have a low forward resistance and near infinity or infinity in reverse bias when tested --out of circuit --- with a multimeter , although I have plenty of digital meters I always use my old AVO 8 as it uses a bit more current , and --to me , is easier to judge .
Of course if you are talking about Germanium diodes that's a different matter.
Of course if you are talking about Germanium diodes that's a different matter.
An ordinary diode out of circuit would read ( assuming you are using the diode test position on a multimeter )approx 0.6V FB ( not 6V ) and o/l RB . The RB of the others you mention are possibly being affected by the circuitry around them , if you suspect they are faulty you would need to unsolder one leg and measure again to prove them .
Still typing as " duncan2 " posted .
Still typing as " duncan2 " posted .
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2.5 volt reverse bias either indicates they are bad (leaky) or they are supposed to be low voltage zeners (maybe nominally a 2.7 volt). Could be either. If they are supposed to be zeners they will have a relatively constant reverse voltage over a range of current. Additional testing would be needed. A power supply (or battery, or wall wart), a couple of series resistors to give currents between a few hundred uA and maybe 50 mA, and measure the voltage. If it’s just a leaky diode, the “zener” voltage won’t even approach constant.
It's important to know how you are determining those voltages. As epicyclic wrote, if the measurement were made in-circuit or it was made with an older analog type multimeter, the different test currents could have a significant effect on the circuit voltages and vice-versa.
So, if instead you used one of the cheap fleabay component testers or something better, such as a Peak-Atlas DCA55 or DCA75 to read the "FB" or "RB" voltage drops, your results could be quite different. And BTW. if they are zeners, you also need a power source with enough test voltage for the zener to conduct. If all you have is say, 3V of battery power, you're likely restricted to 2.5V zener checks.
So, if instead you used one of the cheap fleabay component testers or something better, such as a Peak-Atlas DCA55 or DCA75 to read the "FB" or "RB" voltage drops, your results could be quite different. And BTW. if they are zeners, you also need a power source with enough test voltage for the zener to conduct. If all you have is say, 3V of battery power, you're likely restricted to 2.5V zener checks.
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according to the parts list they appear to be standard as anything else is specified as a zener for example
i dont use cheap testing equipment, its a fluke so quite a reputable make
i dont use cheap testing equipment, its a fluke so quite a reputable make