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Loose connection to Topping A30 Pro caused power cycling, possible damage?

Sarumisono

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Hi Everyone, I hope I am posting this in the correct section.

I recently purchased a Topping A30 Pro to use as a headphone amplifier. When I was testing it yesterday, I had an RCA to 3.5mm cable plugged into the RCA inputs on the amp, and the 3.5mm end to my DAC. I wanted to test out a different source, and without thinking I pulled it out of my DAC and into my phone without turning the amp off. The biggest problem with this is that my phone has a really bad headphone jack which makes rather poor connections, and causes cables to pop out easily. I was playing music from my phone into the amp with my headphones plugged in, and when the cable popped out, I could hear a loud pop in the headphones which is pretty typical when hot-plugging anything, but the amp also clicked on and off once or twice while the connection was really loose in the phone's headphone jack. By clicking on and off I mean that the light on the amp went off, and the little click sound that it makes whenever toggling the power was also made. I then plugged the 3.5mm jack back in and held it in with my hand, turned off the amp, and unplugged it. Did this occur because one of the left/right channel pins on the jack was getting shorted to ground due to the loose connection? I read that the amp could have possibly been entering protection mode or something like that since it turned off and on but I'm not sure. Does anyone know why it would have toggled the power like this? Is it possible that I damaged anything in the amp? I would really appreciate any information that you guys might have on this since I'm pretty worried I may have messed something up.

Thanks in advance.
 

Chrispy

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Well rule number one is don't make changes when things are powered on. Hard to know what you did, but beyond that can't help you with technical analysis, but if it is sounding normal with normal use I think you probably didn't do any damage....
 

Lupin

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Did this occur because one of the left/right channel pins on the jack was getting shorted to ground due to the loose connection?
Most likely.

I read that the amp could have possibly been entering protection mode or something like that since it turned off and on but I'm not sure. Does anyone know why it would have toggled the power like this?
Most likely due the above, you created a short on the input.

Is it possible that I damaged anything in the amp?
The protection mechanisms are there to protect the device under such circumstances as described above.
The protection mechanisms most likely did their job well if the device still works properly once the situation is corrected.

Personally I say never hot plug a 3.5mm/6.35mm jack as you'll most likely create a short when plug/unplugging the jack.
 
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Sarumisono

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Well rule number one is don't make changes when things are powered on. Hard to know what you did, but beyond that can't help you with technical analysis, but if it is sounding normal with normal use I think you probably didn't do any damage....
Yeah... I definitely won't be hot plugging anything in the future.
The protection mechanisms are there to protect the device under such circumstances as described above.
The protection mechanisms most likely did their job well if the device still works properly once the situation is corrected.
Thanks for the detailed response. That's good to hear, these amps should have some kind of protection mechanism built-in right? I just want to be sure that's what I triggered. If I actually did cause any damage, do you think it would be audible/noticeable at all?

Out of curiosity and on the topic of protection mechanisms, does anyone know or have any resources that talk about the design or circuitry that goes into a typical protection mechanism for an amp like this?
 
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