MCH-K38 scare!

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MCH-K38 scare!
« on: 7 May 2019, 06:12 am »
I've had the unit for about 2 years now, and it's been very nice.

I mostly have the unit either on or in standby mode.

Yesterday, I switched off the 4 first channels and on the last two, to try a pair of speakers.
After that was done, I switched off the channels 7-8 and switched on channels 1 through 4.

But there was no sound.  Nothing.  I knew the rest of the chain was working as it should, and tested it again with the last 2 channels.
So, the first 4 channels were dead.  Little LEDs inside seemed on, but no heat came from the left side of the unit.

So, I completely turned it off, took out the power cable and let it sit for the night.

This morning, I plugged it back on, and to my relief, the first 4 channels were alive again and working well.

Yikes!  That was a scare!

So, to owners of the unit, if this happens to you, try to disconnect the unit completely for a while and reconnect later.

I have no idea why it would work, but it did and I was glad.


Re: MCH-K38 scare!
« Reply #1 on: 7 May 2019, 07:04 am »
It is most likely due to the electrical/mechanical relay that got stuck, so power reset fixed it.


Re: MCH-K38 scare!
« Reply #2 on: 8 May 2019, 03:11 am »
Thanks for the explanation.

So, which is better then?
Keep it on standby mode when not in use, or always on, like the old amps?


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Re: MCH-K38 scare!
« Reply #3 on: 8 May 2019, 03:10 pm »
When I push my K38 hard in with very dynamic and bass heavy songs it has shut off the channels and I simply unplug it for a second and they come back. But I am pushing things just to see how much I can get out of the system and it is way beyond safe long term hearing levels.

I will turn my entire system and leave it on when I know im going to be using it. But I turn it off If im not going to be using it for a few days.


Re: MCH-K38 scare!
« Reply #4 on: 8 May 2019, 11:46 pm »
I don't think it matter if you leave it on or turn it off. You can mute the channels using the front panel switch for each channel.
The mechanical relay getting stuck is rare and power cycle will fix it.

If you turn up the volume on a hard to drive speaker until the power supply reaches current limit, it will shutdown for protection (a standard feature of SMPS). So for such case, power cycle will reset it.