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Monitor Audio MASS W200 blown

Jezzer96

Standard Member
I am having a problem with the Subwoofer where it will not turn power up. I have checked the power lead using an alternative cable which I know works so the problem definitely lies with the subwoofer itself. The LED on top of the Subwoofer does not illuminate or flash so i am suspecting it is a PSU related problem.

I have removed the PSU hoping to find an internal fuse that may have blown but this is not the case. I have attached a photo of the PSU and one thing that stands out (when compared with other photos on this forum of a W200 PSU) is the cable towards the bottom heat sink has completely overheated and melted the plastic covering,

The cable is still intact though.

I have approached Monitor Audio and a new board is £ 179. Is there a common fault with the PSU's on these units as I seen a number of similar posts and is there a common failure on these boards.
 

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Jezzer96

Standard Member
Yes the fuse is OK.
I did notice the resistor had developed dry solder joints (the resistor ringed in the enclosed image) so I have resoldered them.

Could this be the fault or more than likely a consequence of another issue?
 

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dobrykamil

Member
That resistor is for main psu, which provides +54V for the main amp. Look at the standby psu instead, since there is no sign of life at all. One of those caps looks a little bulged to me. Also, check those 3 diodes as well ( use the diode mode on your multimeter).
 

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Jezzer96

Standard Member
I only have a basic electrical test meter so cannot check diodes I don't think. They are not "open" when I have checked for continuity. The caps seem ok to me and I have enclosed a different image,

Is there anything else basic that is worth checking? I intend to plug it together tonight to see if the dry joints on the +54V could have effected things.
 

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dobrykamil

Member
If diodes are not open, then they're ok then. Now, check voltage on that 4 pin connector. Black wire is the ground, red should read +7V and white -7V. Blue is the Enable signal for main psu so ignore it for now.
 

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Jezzer96

Standard Member
I connected the cirucit bosrd up to the subwoofer yesterday and there have been no improvements so the dry joint on the resistor was not a reason for the problem.

I am unable to get the +7V when measuring across the 4 pin connector so the is either a problem further up the line or an issue with the multi meter.
 

Jezzer96

Standard Member
We are receiving AC power to the PSU as I have checked near the Blue and Brown cables on the connector near to the fuse.
 

dobrykamil

Member
Ok, but is the amp board still connected to psu? Look for any shorts at the amplifier module.Set multimeter to impedance and check +54 volts circuit as well as the 4 pin connector on both sides, psu and amp.
 

Jezzer96

Standard Member
The amp board is still connected to the PSU and i am measuring DC voltage across the 4 in connector.
on both the red and white connections..

I encountered an issue where the AC mains was not correctly terminated onto the PSU so this the reason why I was getting incorrect readings across the 4 pin connector before.
 
Last edited:

SPaul1

Novice Member
Hi. I have a monitor audio W200 sub aswell that has also blown. After looking for a replacement W200 on eBay, I noticed that they all have a C13 power cable. My subwoofer for some reason has a figure 8 power cable and was wondering if maybe that figure 8 were the ones developing PSU problems and the C13 subwoofers are the updated version that has fixed the issue.
Was just wondering if yours had a Figure 8 or C13 power cable?

Thanks
 

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