Question about Alesis Monitor One Mk2 Speaker
Everything was working fine last night, I wake up this morning and (only) the left speaker is on the fritz. The LED is blinking about 6 times a second, and the speaker itself is making some sort of clicking noise that corresponds with the flashing of the LED.
I'm assuming this is some kind of power issue based on my limited knowledge...
The flashing blue LED and loss of sound on the Alesis M1 powered monitor is caused by failure of capacitor C8 (220uF, 35V) on the power supply board. It dries up due to its proximity to resistor R4 (47K, 2 W) which gets very hot. This is a design fault.
Remove the power supply board (4 corner screws and 2 mains connector screws) and disconnect the two plugs. Carefully desolder C8 and replace it. Its value is not critical (220 to 470 uF will do) but it should be a 105 deg. type, preferably at 50V.
Remove R4 and replace it with a similar resistor with its leads bent so that it is nowhere near C8, otherwise the fault will return. One end may be connected to one of the existing R4 solder pads (furthest from rear of board), and the other to the top end of resistor R3. Check that you have connected it correctly by inspecting the PCB tracks.
Replace the board and all screws and plugs before testing.
Posted on Jan 01, 2008
Hi there, this is a response to Unheard's comment:
"Carefully desolder C8 and replace it. Its value is not critical (220 to 470 uF will do) but it should be a 105 deg. type, preferably at 50V. "
Does anyone know where I can find a part (online) which matches this spec, as I have the exact same problem?
Posted on Oct 20, 2009
C8 was the problem with mine! Thanks for the fix! I didn't put all screws back in the cover until I made sure it worked. FYI the blue/white wires go to the tweeter, I case you don't write it down.
Posted on Jul 17, 2009
Mines got the same problem..i now leave it on all the time,but if it happens to go off the light starts so i switch it off for 20mins with a fan blowing on the back of it and its fine to switch on again
Posted on Nov 27, 2008
I have this exact same problem with my Alesis M1 Active MkII monitor (left)... www.digikey.com appears to have capacitors of the appropriate specs.
I am considering setting up the replacement C8 capacitor with a thin piece of silicon insulation (similar to the silicon used in food baking mats) to place inbetween the replacement C8 capacitor and R4. Does anyone suppose this will work to insulate it properly? I should know for sure in a week or so when the parts arrive.
Posted on Sep 28, 2008
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