Re: Repairing Alesis M1 Active mk2 Monitor Speakers
Well Khron, I'm now hearing sounds coming from the speakers as it's finally fixed!
That missing 6v was from a faulty but new C8 (ELNA Silmic II -35w/220uf), it tested normal out of circuit but once replaced with another everything jumped to life.
After years of no results, It's a strange emotional reunion finally listening to the original speakers that inspired my career again so thank you to everybody that gave input, struggled, provided guidance & solutions especially...
thafx
New Member
Last Activity: 02-12-2021, 12:36 PM
Joined: 11-20-2020
Location: London
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Re: Repairing Alesis M1 Active mk2 Monitor Speakers
hi all
[B]U1 [/B] *powered*
5-7 > 10v with multiple UC3842N & UC8344AN chips
5-8 > less than 1V
R3 & R4 replaced with 47k/2w
D5 (420 & 1/OL in reverse),
R5 (11),
Q3 (NPN 570),
Q4 (PNP 520)
^all new components
with C6+C7 [measuring 330v across ] Im now wondering why there is only only 10v after R3,R4,D5,R5, where would the missing 6v come from?
Q1/Q2 tested...Leave a comment:
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Re: Repairing Alesis M1 Active mk2 Monitor Speakers
Hi again, I inspected the board and found a damaged trace between D2 to C6+. After repairing the trace, I now read 330V across C6 & C7
U1 PIN5->PIN7 reads just under 10v with UC3842N & UC8344AN
PIN5->PIN8 reads less than 1V ( main suspect now )
I have also replaced U2 with a DIP6 socket with a new TCDT1124 chip with no change....Leave a comment:
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Re: Repairing Alesis M1 Active mk2 Monitor Speakers
Hi again and Happy New Year,
Those are readings with the chips off the board
I have traced 240v voltage from the power socket through the circuit upto C6/C7 which does not give a DC voltage reading.
I've removed & tested the New caps on the Ohm meter, they're reading slowly toward infinity.
there is no supply voltage on U1 pin5-7 when powered
I have also moved c8 to c14 (c14 attached at the back), replaced U3-TL431 and tested UC3842N, UC8344AN...Leave a comment:
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Re: Repairing Alesis M1 Active mk2 Monitor Speakers
Following the Instructions here...Leave a comment:
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Re: Repairing Alesis M1 Active mk2 Monitor Speakers
Hi Khron , thank you for your time & excuse my blunt post.
I do have a Multimeter, everything replaced is new & was checked to its specification.
After going through this thread multiple times (similar situation to markovitch's & Shabazxz's posts)
Im suspecting the odd TL3842P chip to be the suspect, (I ordered UC8342N but received this IC)
The IC readings :
GM3842 / PIN7=127 / PIN8=565
TL3842 / PIN7=413 / PIN8=430...Leave a comment:
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Re: Repairing Alesis M1 Active mk2 Monitor Speakers
Hi all, this is my 5th attempt to resurrect this speaker
Ive just replaced
r5,r11,r15,r16,r18 -
d1,d2,d3,d4,d5,d6,d7,d9,d14,d15,d16, -
q1,q2,q3,q4,q5,q6,q7 -
c1, c2, c6, c7, c8, c35, -
rt1 -
f1 -
u1 (TL3842P) + dip8 socket -
after all this,plugged in and switched on, no sign of power, dead, no fuse pop, nothing. all solder joints have been checked...
does anyone have any advice at this stage ?
cheersLeave a comment:
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