Question about JVC MX-KB30 CD Shelf System
How hard do u need to press with the small screwdriver? I tried this and the white piece didn't feel like it pressed in at all. The system still shows protect also.
Posted on Feb 05, 2010
This solution worked perfectly. Thanks for posting
Posted on Mar 21, 2008
I know I'm finding lots of old posts about this JVC model MX-KB30 "PROTECT" problem but - I FIXED IT!!!! 8-) Daugter had the same difficulty after a series of power outages. Figured it had something to do with the speaker circuit board. Decided to look for a reset on the board itself. Not sure that I found one, basically becuase there was not a perception of a button pressing down, but the "PROTECT" cleared and the sound is coming through the speakers again. The sterio works fine. First - as when working on all electronics - unplug the unit and make sure all static electricity has been discharged before working on it. You will need a small jewlers philips screw driver as well as a mirror for looking down on top of the electrical components. Remove the cover of the sterio surrounding the sides and top of the unit - there are screws on the sides, top and around the edges of the back fo the unit related to this piece. You do not have to remove any other pieces. There will be a circuit board attached to the back center of the unit that has a black cable running to the headphone plug and the speaker connections are also running through this board. If you face the front of the unit, looking at the sound circuit board from the right side, there will be a small black - square looking - voltage regulator (I think that's what it is anyway) that you will see some voltage information and some switch setting pictographs (along with the numbers 1, 2, 3). On top of this black unit (here is where you need the mirror) there is a square hole that looks down inside this unit as well as a round hole that you will see white plastic inside. Using the jewlers screwdriver, carefully press on the white plastic once or twice (I couldn't tell that it had pushed down) particularly becuase I have no clue how sturdy this piece is. With the cover still off the unit, plug it in and make sure the "PROTECT" message has disappeared and the speakers are working again. That's exactly what I did and the darn thing started working again. Maybe I just got lucky, but this is a nice sounding unit and it would be a shame to see folks toss it away for such a simple fix if that is indeed what did it. Enjoy!
Posted on Apr 23, 2007
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Oct 16, 2015 | Audio Shelf Systems
It is possible that the amplifier had encountered a fault with a higher current drain which had triggered it to a protection fault condition. The fault can be with your output drivers. Please check for short on the outputs fitted for both the channels. Use a meter after disconnecting to check for short in the drivers. Disconnect the positive and negative voltages to the output and see if the protect changes. Even a fault in the preamp stages that drives in high current into the output can shut the Amplifier. Sometimes this can be a noise which can be a HUM or HISS before the protect works. Faulty capacitors in these circuits also can cause similar issues and needs close observation.You need to confirm and replace the specific stages or outputs. If not there can be issues in the mother board. Maybe the protect circuit by itself is shutting off due to a faulty bias or there is a leak in any voltage/current sensing circuit. Also disconnect the speakers and test, if the amplifier comes out of the protect mode then check for short on the speakers.
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