Hi all
I have 1 Mission "M-Cube" subwoofer and I need some help...
The problem is that the primary switching mosfets (IRF740) gone up in smoke and I whant to fix it.
My problem is that there is some damage (melted film) on the transformer and I don't know if it is damage to the windings.
So before I smoke 2 new mosfets can someone give me some pointers ?
Personally I don't like switch mode power supplies in audio gear and I would prefer to build a normal one with a toroid but I dont know the voltage and VA output rating of the original supply.
Can someone help ?
The Mission site is nice but the contact page is not working.
Ric
I have 1 Mission "M-Cube" subwoofer and I need some help...
The problem is that the primary switching mosfets (IRF740) gone up in smoke and I whant to fix it.
My problem is that there is some damage (melted film) on the transformer and I don't know if it is damage to the windings.
So before I smoke 2 new mosfets can someone give me some pointers ?
Personally I don't like switch mode power supplies in audio gear and I would prefer to build a normal one with a toroid but I dont know the voltage and VA output rating of the original supply.
Can someone help ?
The Mission site is nice but the contact page is not working.
Ric
Hi RS,
Could be a transformer malfunction. Pity you are not closer a I could have had a look at it.
Have a look at this link for some pointers.
Basic Amplifier Repair
Rob.
Could be a transformer malfunction. Pity you are not closer a I could have had a look at it.
Have a look at this link for some pointers.
Basic Amplifier Repair
Rob.
Hi
Thanks for the answer
I'm very comfortable with electronics (I worked over 10 years with industrial electronics).
I only ask for help because I was hopping that someone allready fix one of these sub amps.
The other thing is I never seen a HF transformer fail in a power supply (and I repaired loads of then).
In my opinion the melted film on the transformer was due the close proximity of the transisfors to the transformer.
The 2 mosfets have a hole on them and there was lots of black scrap caused by smoke/sparks around the IRF740 / transformer and on the board.
Going to try to take some pictures for you to have a better idea.
Ric
Thanks for the answer
I'm very comfortable with electronics (I worked over 10 years with industrial electronics).
I only ask for help because I was hopping that someone allready fix one of these sub amps.
The other thing is I never seen a HF transformer fail in a power supply (and I repaired loads of then).
In my opinion the melted film on the transformer was due the close proximity of the transisfors to the transformer.
The 2 mosfets have a hole on them and there was lots of black scrap caused by smoke/sparks around the IRF740 / transformer and on the board.
Going to try to take some pictures for you to have a better idea.
Ric
Ok, small update
The thermistor (DSP104) in line with the 240V is blown/kaput (if you look closely you will see that there is a bit missing on the left side)
Gate resistors are fine and can't find more damage.
All point to a power line spike or someone put the selector for 120V.
Merry Christmas everybody
Ric
The thermistor (DSP104) in line with the 240V is blown/kaput (if you look closely you will see that there is a bit missing on the left side)
Gate resistors are fine and can't find more damage.
All point to a power line spike or someone put the selector for 120V.
Merry Christmas everybody
Ric
Ok
I have got all the parts together and hopping to fire it up today
Part count (damaged)
2 x IRF740
1 x DSP 104 10 Ohm 6Amp thermistor
1 x MUR420
2 x 235 Ohms 1% resistor
2 x 1n5345b 15V zener diode
Replaced the 235Ohm resistor with 240Ohms because I could not find the correct value but the schematic says 100Ohm...
Will report back as soon I put everything together
Finger crossed
Ric
I have got all the parts together and hopping to fire it up today
Part count (damaged)
2 x IRF740
1 x DSP 104 10 Ohm 6Amp thermistor
1 x MUR420
2 x 235 Ohms 1% resistor
2 x 1n5345b 15V zener diode
Replaced the 235Ohm resistor with 240Ohms because I could not find the correct value but the schematic says 100Ohm...
Will report back as soon I put everything together
Finger crossed
Ric
Last edited:
IT WORKSSSSSS!!!!!!!!!!
I protected the damaged film on the transformer (picture on post 4) with a clear sealant used in aerospace.
I damaged a track but that was ease to fix.
If you are fixing one of these BASH power supplies please be carefull the heatsint on the primary side with the MosFets is live and there is no indication/warning of that in the board.
If someone needs the schematic for this amp (Mission M-Cube) the Klipsh RW10 is exactly the same and can be found on the net or send me a message.
Time to fix my XR-225 hibrid amp...
Ric
I protected the damaged film on the transformer (picture on post 4) with a clear sealant used in aerospace.
I damaged a track but that was ease to fix.
If you are fixing one of these BASH power supplies please be carefull the heatsint on the primary side with the MosFets is live and there is no indication/warning of that in the board.
If someone needs the schematic for this amp (Mission M-Cube) the Klipsh RW10 is exactly the same and can be found on the net or send me a message.
Time to fix my XR-225 hibrid amp...
Ric
Last edited:
Hey cool, the Martin Logan Dynamo (original) also has that same BASH power supply, and mine has one of the IRF740 reading resistance and the other completly open. I plan to replace both - is there a good substitute for these?
Looks like someone already replaced the two IRF740s, but it appeasr they did a crappy job as the mosfet tab was not isolated from the sink, and re-blew the mosfet(s).
You say the sink is live? But the two mosfets have isolator pads, just like yours shown...this sink should not be live, correct?
Anyway, I may take you up on the schematics...I love this site!
Looks like someone already replaced the two IRF740s, but it appeasr they did a crappy job as the mosfet tab was not isolated from the sink, and re-blew the mosfet(s).
You say the sink is live? But the two mosfets have isolator pads, just like yours shown...this sink should not be live, correct?
Anyway, I may take you up on the schematics...I love this site!
Last edited:
Hi joh65
The laptop with the schematic is dead and I need a USB adapter to get the stuff from the hard drive.
Look on the net for the part number on the transformer you get more hits that way.
This was the way I came across the schematic for the RW-10.
If the mosfets IRF740 are dead you going to have to remove the small board near the heatsink (be careful mainboard is double sided) and measure the zeners and gate resistors.
Check the 2 big diodes after the transformer I had 1 shorted.
Good luck
The laptop with the schematic is dead and I need a USB adapter to get the stuff from the hard drive.
Look on the net for the part number on the transformer you get more hits that way.
This was the way I came across the schematic for the RW-10.
If the mosfets IRF740 are dead you going to have to remove the small board near the heatsink (be careful mainboard is double sided) and measure the zeners and gate resistors.
Check the 2 big diodes after the transformer I had 1 shorted.
Good luck
I just picked one of these up for £25 intent on pulling the drivers out. Then picked up some kef 2005.2 fronts for desktop use and thought I may fix this M3 for them. I tried to download the schematics but just got game links and a foreign language browser popping up who's uninstall is convoluted and illegible. A bit like this sentence. Enough of that though. Does anyone have a known good link to the drawings? I could just swap the fets, but the x-over on these goes between 250 and 300 which is a very narrow adjustment, set far to high for my intended use.
My other option is a 16A game system psu and a car amp. Dirty, but it could work.
My other option is a 16A game system psu and a car amp. Dirty, but it could work.
Hi
Have a look here:Klipsch Promedia V.2-400, V4.1, V2.1, And V5.1 Amplifier Repair
The Mission one is the V5.1
Is it completely dead ?
Ric
Have a look here:Klipsch Promedia V.2-400, V4.1, V2.1, And V5.1 Amplifier Repair
The Mission one is the V5.1
Is it completely dead ?
Ric
Thank you.
To be honest I didn't check. I got it as broken, from a chap who gets a few. If I'm happy I can change the crossover then I will look into it more. I got it for the drivers really, but it might get fixed instead. A fet has failed and I see no other damage, though some solder splatter is present under the edge of that heatsink where a hole goes through the board. Not component sized, but more like where the wall of a can might be grounded. A couple of mm maybe.
I will go and have a look at these drawings. It's new to me, but I have an idea what to expect.
Thank you
To be honest I didn't check. I got it as broken, from a chap who gets a few. If I'm happy I can change the crossover then I will look into it more. I got it for the drivers really, but it might get fixed instead. A fet has failed and I see no other damage, though some solder splatter is present under the edge of that heatsink where a hole goes through the board. Not component sized, but more like where the wall of a can might be grounded. A couple of mm maybe.
I will go and have a look at these drawings. It's new to me, but I have an idea what to expect.
Thank you
It's class AB. It takes nearly 400w out the wall. How b****y loud is this thing.
I have about half a square foot under each front seat in the car. Actually in the floor. I think they are going in there if it's that standard. I will get something smaller to partner the Kef eggs on the desktop.
I'm still looking though...
I have about half a square foot under each front seat in the car. Actually in the floor. I think they are going in there if it's that standard. I will get something smaller to partner the Kef eggs on the desktop.
I'm still looking though...
I was starting to question my sanity until you said that.
I'm not really interested in the sub unless the crossover can be changed. I think I will knock the idea on the head and box up just one of the drivers with a used car amplifier and PC power supply. You don't know what the driver actually is do you? While it works with that half a foot, My ear finds it over does it around 80-100hz and can probably manage better below 40hz with a bit more space.
Might you like any of these boards?
I'm not really interested in the sub unless the crossover can be changed. I think I will knock the idea on the head and box up just one of the drivers with a used car amplifier and PC power supply. You don't know what the driver actually is do you? While it works with that half a foot, My ear finds it over does it around 80-100hz and can probably manage better below 40hz with a bit more space.
Might you like any of these boards?
Thanks for the offer but no, I only looked for the schematic because I also bought a faulty one of thebay, fixed and now using it.
Properly repaired it does give some punch to the sound, I'm driving it with my technics DSP and main amp (vintage Class A Kelvin labs) together with some nice speakers and believe me watching movies in 2.1 makes a lot of difference.
About the drivers I know nothing about them but they look pretty good and heavy.
Ric
Properly repaired it does give some punch to the sound, I'm driving it with my technics DSP and main amp (vintage Class A Kelvin labs) together with some nice speakers and believe me watching movies in 2.1 makes a lot of difference.
About the drivers I know nothing about them but they look pretty good and heavy.
Ric