Hi there!
I have some problems with a powered subwoofer Mackie 18" the amplifier was damage so i check and found the FDP30n25 in short and replace them and the IRS20957s too.
So i turn it on with 8ohm speaker(tests)and music playing and dont work, everthing seems ok... no clip signal and the output relay clicked 🙂 . and then some minutes later start working 😕 for some seconds then stoped... and works random (more time dont).
I check the CSD and see some triangle signal ( and 10v when is working) i disconect de SD signal removing the D3 and nothing changes.
I can see my "music" (PWM) in R13 and check some voltages and looks ok:
(11)Vcc=12.4v
(1) Vdd=10.5v
(15) Vb=14v
(2) CSD=10v (working)
Rails: 80v +/-
One weird thing in the pcb the R18 for the OCSET are gone the same for R24 in the CSH.
I don know why is my CSD signal i belive the OCSET an CSH are in the max because mackie use they discrete UVL an OVL system then shutdown using the SD signal.
What i missing?
note: the schematic is not the correct model but i dont see major diferences, one thing is my subwoofer is only 1 channel
I have some problems with a powered subwoofer Mackie 18" the amplifier was damage so i check and found the FDP30n25 in short and replace them and the IRS20957s too.
So i turn it on with 8ohm speaker(tests)and music playing and dont work, everthing seems ok... no clip signal and the output relay clicked 🙂 . and then some minutes later start working 😕 for some seconds then stoped... and works random (more time dont).
I check the CSD and see some triangle signal ( and 10v when is working) i disconect de SD signal removing the D3 and nothing changes.
I can see my "music" (PWM) in R13 and check some voltages and looks ok:
(11)Vcc=12.4v
(1) Vdd=10.5v
(15) Vb=14v
(2) CSD=10v (working)
Rails: 80v +/-
One weird thing in the pcb the R18 for the OCSET are gone the same for R24 in the CSH.
I don know why is my CSD signal i belive the OCSET an CSH are in the max because mackie use they discrete UVL an OVL system then shutdown using the SD signal.
What i missing?
note: the schematic is not the correct model but i dont see major diferences, one thing is my subwoofer is only 1 channel
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I have had, on a few occasions, due to the quality of main smoothing capacitors, they go intermittent and upset the over/under voltage detector. I had one with intermittent output, that was the gate feed resistors and gate turn off diodes that caused the output failure.
If the TL081 were to be faulty, you would have no saw tooth because that generates the saw tooth unless the audio mixer TL was at fault but you say you have audio going in.
Check the power supply is the first thing to do and make sure you discharge the main supply lines before any work!
If the TL081 were to be faulty, you would have no saw tooth because that generates the saw tooth unless the audio mixer TL was at fault but you say you have audio going in.
Check the power supply is the first thing to do and make sure you discharge the main supply lines before any work!
I replace the TL081 but no change, so removing the gate resistors and diodes for check and they are ok (20ohms and 1n4148) i returned in their place and then works.
Maybe is the quality of the solder but sees fine, i blame the heatsink. they are very big and the PCB support almost all the weight and this components are close to the mosfets and broke/damage the solder.
Then resolder the gate R and D was the solution.
Thank you JonSnell and ionutzxpo!
Maybe is the quality of the solder but sees fine, i blame the heatsink. they are very big and the PCB support almost all the weight and this components are close to the mosfets and broke/damage the solder.
Then resolder the gate R and D was the solution.
Thank you JonSnell and ionutzxpo!
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