I’m in the process of setting up a tube amp testing bench, and have built an 8ohm dummy load with BNC connectors to connect an Oscilloscope. Before hooking up anything “important” I thought I would test the dummy load with a cheap chip amp, but this amp has a built in speaker short circuit protection. Hooking up the dummy load on the speaker terminals seems to trigger this protection circuit, which was not what I expected.
I’ve verified that there isn’t a problem with the other connectors attached to the dummy load (the oscilloscope) by taking another 8 ohm resistor and hooking it up across the speaker terminals directly, with the same result.
Since this isn’t what I expected, I thought I would appeal to the collected wisdom just to get some feedback, before hooking it across an expensive output transformer. Have dummy loads been known to trip protection circuits?
I’ve verified that there isn’t a problem with the other connectors attached to the dummy load (the oscilloscope) by taking another 8 ohm resistor and hooking it up across the speaker terminals directly, with the same result.
Since this isn’t what I expected, I thought I would appeal to the collected wisdom just to get some feedback, before hooking it across an expensive output transformer. Have dummy loads been known to trip protection circuits?
What is the impedance of the dummy load measured with a DVDM ?
What is the dummy load ? ( it ought to be a power resistor )
What is the dummy load ? ( it ought to be a power resistor )
The second resistor (the one I hooked up directly) is an 8 ohm 25W ceramic power resistor. The first one is an 8 ohm 50W wirewound. Both measure within spec.