Hi, I'm trying to repair a friend's cheap USB capable turntable. It's powered by a 14V wall wart and has a lot of SMD electronics inside it.
I found an apparent Schottky diode (SMD component with a cathode band marked as SS34, according to Vishay has a 40V max DC blocking voltage) with some odd behavior- I can measure single digit resistance across it in either direction using an ohmmeter. When the unit is receiving power from the wall wart I can't measure a potential difference across the diode, though I can measure about 14V from another, nearby diode. I tried shorting across the suspect diode with a normal 1N4004 diode but that didn't help (not surprising given it's acting like a wire on it's own).
My questions are 1) this is bad behavior for a Schottky diode, right? and 2) is there any reasonable circuit design that would have single-digit resistance in both directions in parallel with a Schottky diode? I have no schematic and wasn't able to find one online.
Trying to decide whether it's worth it to try and replace the Schottky or not. Thanks for reading!
I found an apparent Schottky diode (SMD component with a cathode band marked as SS34, according to Vishay has a 40V max DC blocking voltage) with some odd behavior- I can measure single digit resistance across it in either direction using an ohmmeter. When the unit is receiving power from the wall wart I can't measure a potential difference across the diode, though I can measure about 14V from another, nearby diode. I tried shorting across the suspect diode with a normal 1N4004 diode but that didn't help (not surprising given it's acting like a wire on it's own).
My questions are 1) this is bad behavior for a Schottky diode, right? and 2) is there any reasonable circuit design that would have single-digit resistance in both directions in parallel with a Schottky diode? I have no schematic and wasn't able to find one online.
Trying to decide whether it's worth it to try and replace the Schottky or not. Thanks for reading!
Um... Your diode reads low resistance both ways, and no voltage drops across it? Sure sounds like it is shorted so far.