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250W KRK 10s Active Sub Monitor Unable to Power On despite Intact Fuses

solaraxis

Member
Wow I hope this isnt a huge deal but the amp is actually 250 watts. Bit of an oversdsight when I labeled this thread....
 

Diver300

Well-Known Member
One power pin should be no resistance to the thermal fuse.

Can you get to the pins of the voltage selector to measure resistances there?

The fact that the amp is 250 W rather than 150 W doesn't make any difference.
 

solaraxis

Member
I can't without cuitting into the factory shrouding and possibly more insuklation, nothing power related is exposed on the amp from factory really
 

solaraxis

Member
after i connected the fuse. with the fuse connection removed from the brown wire i tested the resistence between the exposed brown/WH, and it is connecting with no resistance.
 
Last edited:

Diver300

Well-Known Member
If there is no resistance between the brown and white wires with the new thermal fuse removed, the old one is probably OK.

From the power inlet to the transformer, there is:-
1) The fuse in the power inlet
2) the mains switch
3) the voltage selector switch
4) several soldered connections.

As the power thermal fuse is OK, or bypassed by the new one, then one of those 4 things is probably faulty. From this photo it looks as though everything is covered in heat shrink.

I think that you will have to cut some away to work out what has failed. I would start with the back of the on-off switch.
 

solaraxis

Member
power inlet fuse tested and okay
I was under the impression this was caused by an electrical feedback loop. maybe that is not the case? hmm
 

Diver300

Well-Known Member
There's no feedback. It's a direct connection. You could cut the transformer wires and poke the ends into a mains outlet and it would work. I'm not suggesting that you do that, as one slip and you could get a shock.

My guess would be that the switch is faulty.

I've just seen your latest picture. I can't see which bit of metal looks discoloured, but I suggest you cut the tie-wrap and insulation from the back of the switch.
 

solaraxis

Member
i am now getting a connection between the pins, i cleaned the contact of the white wire/switch connecton. 0 ohm's.
 

solaraxis

Member
I plugged in AC to the wall, i heard a sound like a switch flipping, the light indicating power was not on, I unplugged the wall outlet and the switch sound happened again, rechecked for ohms on the power pins, plugged back in, turned switch on, I heard no switching sound this time and it is not turning on.
 

solaraxis

Member
2020-01-30_16-25-13.jpg
Here is what it looks like wiuthout the white wirwe in that hole. is it supposed to be removable? what is that little pin sticking up above the contact?
 

solaraxis

Member
Success! Turns on and everything works now. All I had to do was clean the connection on the power switrch and re-solder the white wire to it. Therre is a bit of low level noise coming from all of the speakers. Idk where its coming from but im super relieved to have this working finally. Think the noise is the usb interface. i unplugged it and the noise vanished lol
 

solaraxis

Member
Been mixing with it for hours and haven't had any issue. The people who use this forum are great, thanks for having patience and walking me through all this stuff, I wouldn't have been able to afford a technician and I wouldn't have learned a thing if I could afford one, I feel like I've come back from a weekend workshop. Thanks again.
 

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