Alesis m1 active mk2

[Strobe7]

Hi guys,

I'm new here and have read through the several other threads re the repairs other members on these monitors, and have started the repair process on mine.

One of the speakers just stopped working one day after leaving them on over night and blow the fuse and I found visible damage to c6, c8, c35, r18, r11, rt1, q4, and d15.

The board is also burnt around r18 and r11 but compared to a couple of the pics of damaged boards a few of you guys have posted it seams I was lucky.

I have order replacements for the parts I found damaged and also for the remaining a caps on the board and have started the desoldering mission...

So far I have only removed 3 parts and this has been stressful. The so called helping hands I have have been more of a hinderance then a help, what do you guys use to hold large boards like this one and is there something you recommended?

[stj]

Re: Alesis m1 active mk2

foto's - both sides at hires.
and make sure the area is well lit - some people post foto's that look like they work in candle-light!

[Strobe7]

Re: Alesis m1 active mk2

Hopefully these are worthy pictures

[Strobe7]

Re: Alesis m1 active mk2

Hopefully they show up this time

[Strobe7]

Re: Alesis m1 active mk2

Sorry can only do 1 at a time from my ipad

[Strobe7]

Re: Alesis m1 active mk2

[stj]

Re: Alesis m1 active mk2

you need the schematics to find what the burned parts are and find the cause.
Q1 is probably shorted btw - just my suspicion based on how close it is to the resistors.

also, d6 & d7 look like they are related to the big resistor.

[Strobe7]

Re: Alesis m1 active mk2

Khron666 uploaded this service manual in a previous thread https://www.badcaps.net/forum/attach...4&d=1383865634

[Strobe7]

Re: Alesis m1 active mk2

How do I test to see if the MOSFET is shorted?
And thanks I have 9extra diodes after having to buy 10 to replace d15 so I'll check and replace those two

[Ozyris]

Re: Alesis m1 active mk2

Hi Strobe7. I would suggest taking a read through the thread started by firespace on precisely this topic. There is a huge amount of info there on fixing these very nice speakers, including some contributions from some rather clever chaps, including LuigiDJ and Khron666. Some modification to the layout of these power amps will prevent the problem happening again. Good luck and keep going till you've got it sorted!!

[lexwalker]

Re: Alesis m1 active mk2

Hopefully they show up this time

You should scrape off those degraded glue as well, especially those that have turned brownish....

[Strobe7]

Re: Alesis m1 active mk2

Hey, thanks guys for all your support so far.

So far I have removed all the damaged components that I mention in original post and have also removed the remaining caps on the not working power supply board.

On the other speaker which didn't have any problems I removed and replaced all capacitors on the power supply with appropriate replacements and upon powering it up, it worked as expected.

I haven't yet started replacing parts on the damaged board as I have been preparing it by cleaning it up and repairing damage.

As lex walker suggested I have removed the crappy glue from various places on the board, i have cleaned off the burnt areas of the board around a few resistors. I have also spent a large chuck of time repairing damage that I caused due to poor desoldering of 2 capacitors and a transistor which while removing I caused the solder pads to lift from the board.

When I'm certain the board is working I will start populating the board again and hopefully have a pair of working monitors.

At least i learned few things and was able to pick up on my mistakes early before completely destroying something.

In case you were wondering I was initially attempting to desoldering parts with an iron that wasnt hot enuff and without a properly maintained tip, and if that wasnt bad enuff I was to impatient to wait the 2 days for my order to arrive and wasn't using flux either. And the result of those mistakes was lifted pads on the 3 parts I removed and a whole lot of wasted time trying to desolder like that and then investing how to repair the damage and then the time repairing the damage

My amp/ crossover board is dated 2003 but I am yet to be able to find a date code on the power supply board, possibly still covered in the large amount of glue that was covering half the board.

[Ozyris]

Re: Alesis m1 active mk2

Wonder how Strobe7 is getting along...

[Strobe7]

Re: Alesis m1 active mk2

It's coming along but Unfortunently I missed ordered and had to wait for the right part to be sent out, should have it early next week, hopefully I'll have some good news to share then.