Coldamp cracks after turned off

[Torbjs]

Hi, I have a problem with a Coldamp Sonora kit I have put together. It has worked perfectly until tonight, when I managed to turn it on without any speaker load on the speaker-terminals.

This resulted in the green light on the board to dissappear, and the amp sends out a loud bang after I cut power. The bang is about 5 seconds delayed after the switch is turned off, and is so loud I don't dare to have my speakers connected anymore.

Does anybody know what might be wrong?

thanks!

[Th3 uN1Qu3]

I think you fried the amp. Most likely it wasn't designed for (or protected against) working without a speaker connected, and it went into self-oscillation.

[Torbjs]

Ok, but the amp still works fine when it's on. No difference in sound quality, so I've been wondering if it is the psu or something. But the psu is integrated on this amp, so it's not that easy to test with a new one.

[Th3 uN1Qu3]

Oh, so you're afraid of keeping the speakers connected to the amp after you shut it down. I understand now.

The power supply shouldn't have anything to do with it. There should be some parts in charge of pop filtering (a resistor and a cap most likely), check if those have failed. Do you have the datasheet of the IC used in the kit?

[Tekko]

Oh yes who can forget him and his sock puppet, aint he still around under the Ssassen name or am i wrong ?

Anyways i'd take the amp back to the manufacturer rather than trying to fix it myself.

[Torbjs]

yeah, I know. It's just that I live in Norway, so the shipping fees are quite high. But I have contacted them by mail and they gave me some points to measure voltage on for a start. I'll look into that today, and then I'll start testing resistors.

[Torbjs]

Well, I didn't know I was supposed to hate Coldamp. I'm sorry for posting and goodbye.

[Pano]

Sorry Trobjs, the guys here can be kinda rough at times. It has nothing to do with you, Coldamp has a bad history around here.

Sorry for your troubles, you should probably just return it. Ask for a full refund, including shipping.

[Torbjs]

Just wanted to let you know that the amp is now back in business. There was a faulty connection on the signal-leds-output connector, and this resulted in the cracks which I described in my initial post. I sent it to Coldamp and the unit was returned to me in just a few days, no charge at all. So I'm very pleased with Coldamp, and to me they seem very service-minded and easy to communicate with.

[ssanmor]

Thanks for the feedback and kind words.
To be sincere, it was not completely Torbjs' fault, because the pins for the LEDs are relatively close to each other (standard 2x5pins 0.1" header) and shorting some of them together can cause damages. We'll warn about this in the datasheet and also we'll start including a flat cable + connector with each amplifier to reduce the possibility of making this kind of error.