What to do with...

[Lt.Dan]

I have this old Main board from one of my LV 6548's that went toast. MPP sent me a brand new one to swap in, but I just dont have the heart to throw this one away.

What can I do with it? Anybody think its fixable? There is no obvious damage/burning etc. I just kept getting "Bus soft start failed" and it wouldn't turn on.

This is a picture of it in the unit. Its the large board on the left.

 

[OffGridInTheCity]

I never seem to have good luck fixing things - but I've seen several youtubes where folks just dig in and start replacing the mosfetts etc and it sometimes works. So look for burn spots, use a voltmeter to check mosfetts, etc? and perhaps don't follow my example of self-defeat before I even try

 

[brewmatic]

Most like some MOSFETs are fried. But you need to have tools and knowledge to find a real reason. You can try to sell this board on eBay.

 

[RCinFLA]

Looks like two high frequency transformers on left side are 48vdc to 200 vdc boost, likely one for each AC 120v phase. Far left heat sink has the DC-HV DC boost MOSFET's. The rectifiers for HV DC could be sharing the left or center heat sink. Two large caps in front left are likely the HV DC filter caps with about 300-350v rating.

Middle heat sink has the HV DC to Sinewave PWM chopper MOSFET's , likely two separate H-bridge MOSFET's for each 120v phase.

Torroids are part of PWM to sinewave output filtering.

Not much surge current capability in this high frequency design.

If MOSFET's are toast it is likely either the ones on far left heatsink or center heat sink, not both.

My first guess would be DC to HV DC driver MOSFET's on left heatsink. These are ones most likely to go due to an output load surge current. With load surge, the transformers saturate and the MOSFET's current for 48v to 180v boost circuit shoots up to destructive level. There is suppose to be current sense detectors to prevent too much current but they don't aways work fast enough. These MOSFET's look like they are very easy to get to on very left outside facing heatsink.

 

[Boondock Saint]

1) Sell it on Ebay and get whatever $$
2) Find an electronics repair shop and ask them to have a go at it for a maximum price you're will to pay and keep it.

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