Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => AmpTools/Tech Tips => Topic started by: smackoj on August 07, 2025, 02:05:10 pm
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Hi old friends; I have a KMD GV60D hybrid amp (made in UK mid 80"s) SS preamp with 2-6L6 pwer tubes. I have the chassis out and was randomly checking diodes with my Fluke meter. I found 2 identical side by side on the power section board. One tests normal, short beep and a reading. The 2nd one has a long beep for as long as I hold the probe on it and it shows a much smaller reading than the first one. Is this continuous beeping telling me the diode is bad? I don't know if this is a Zener or not? I found a poor quality schemo but the board has no numbering on it so I am not sure where it's at on the schemo. It's a small diode and I cannot read the number as it sits on the brd.
Thanks amigos
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to properly test a diode, one side needs to be lifted(out of circuit), using OHMS not continuity: one direction will read very high resistance(many k-ohms to infinity), reversing the leads should read a low resistance (ohms to hundreds of ohms)
zeners can only be tested for shorts with an ohm meter.
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Thanks Shooter that's good info.......much appreciatedJack D
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Many Fluke multi meters have a diode testing function. It works well, but I had to look at the manual to figure out how to use all the features, including what the sound meant.
Go to Fluke.com, and use the fluke chat bot -- you can enter "user manual" and your model number and it will give you the link. Really worth it.
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Good info. Thank you