Hi,
(This is my first ever post on badcaps.net, (looks like a great place by the way) so please be gentle with me as i have very little real world experience practical or otherwise mending electronics, I know very little about capacitor ratings or the contextual meaning of these ratings within circuits).
I have a pair of Alesis M1 Active mk2 Monitor Speakers, they are wonderful, however recently one of them has developed a fault. When the monitor is switched on the blue LED power indicator simply flashes and there is no sound from the drivers when audio is sent to the monitor.
Fortunately I have been able to track down what I believe to be the cause of this common fault (although sadly Alesis won't acknowledge the issue) with a few trusty interweb searches.
Here is what I have found so far-
This first link is a blog entry "Keith's Electronics Blog" is about an apparently similar or possibly identical issue, and gives a brief explanation on how he fixed it, as well as extremely useful comments on other peoples observations and issues they have encountered with these speakers, and the suggested fix. (I also posted one under the name BlueBlink if anyone can answer it)
http://www.neufeld.newton.ks.us/elec...#comment-26043
This second link was where Keith obtained his information on the suggested issues and fixes and can be found in the blog posting but I have included it here to save people looking.
http://studio-central.com/phpbb/view...t=554&start=17
What I have learnt from reading ALL the comments both on the blog and the studio-central posting is that essentially Alesis asked another company to build the PSU section of the monitors amplifier board which resulted in a poor design-
The power supply, apparently, was designed by a different engineering group from that of the rest of the speaker. Their mission was to cut the cost, weight, and size of Alesis power supplies by designing switching power supplies to replace the traditional analog ones. The M1 Active Mk II contains one of the first switching power supplies designed by this team – and, as we all now know, they didn't quite get it right. The power supply is sensitive to spikes in the AC voltage and slowly cooks itself to death.
(Thanks to -Obscuro for the information)
The upshot of all this is, that amongst other issues people have encountered, the main problem seems to be 2 poorly placed capacitors dry up and fail, these being C8 and C35 (see the pictures of the circuit board on the blog link I included).
Since I don't have a ESR tester and C8 and C35 capacitors seem to present the most common problem people have experienced, I would like to try to fix this first.
However to add to the complication Alesis or the PSU manufactures weren't consistent when installing these capacitors and it seem at least two types were used for C8.
220µf 35 V and a 330µf 35 V.
In my monitor C8 and C35 capacitors are the following-
C8- JunFu WJ105 ºC 0304 220µf 35 V green coloured cap
C35- JunFu HK105 ºC 0306 1µf 50 V navy blue coloured cap
I have subsequently discovered from your wonderful forum that JunFu or Jun Fu capacitors are 'bad caps' so my questions are these.
What is the absolute best capacitor to replace these with given their use in a high grade audio monitor and tendency to dry up because of poor placement?
Should I use the same rating capacitors, or would another rating fix the issues better?
Should the capacitor be polarised or non-polerized?
(I'm guessing non as apparently it's apparently AC voltage but I'm really just working with others information as i know so little).
I am considering soldering C8 in on the back of the board to avoid the heat, but as you can see there isn't much room, ideally I would like a replacement component that is the best quality possible, can handle the heat and permanently fix this problem and stop it ever reoccurring.
So far I have found these-
http://cgi.ebay.co.uk/Elna-Cerafine-...#ht_500wt_1154
Will they work? Are they any good?
Can anyone suggest the best cap for the job? Or any other helpful advice?
P.S - Here are some pictures of my units board so you can see for yourself.
http://www.flickr.com/photos/1229014...7624827549078/
Kind Regards,
Joe.
(This is my first ever post on badcaps.net, (looks like a great place by the way) so please be gentle with me as i have very little real world experience practical or otherwise mending electronics, I know very little about capacitor ratings or the contextual meaning of these ratings within circuits).
I have a pair of Alesis M1 Active mk2 Monitor Speakers, they are wonderful, however recently one of them has developed a fault. When the monitor is switched on the blue LED power indicator simply flashes and there is no sound from the drivers when audio is sent to the monitor.
Fortunately I have been able to track down what I believe to be the cause of this common fault (although sadly Alesis won't acknowledge the issue) with a few trusty interweb searches.
Here is what I have found so far-
This first link is a blog entry "Keith's Electronics Blog" is about an apparently similar or possibly identical issue, and gives a brief explanation on how he fixed it, as well as extremely useful comments on other peoples observations and issues they have encountered with these speakers, and the suggested fix. (I also posted one under the name BlueBlink if anyone can answer it)
http://www.neufeld.newton.ks.us/elec...#comment-26043
This second link was where Keith obtained his information on the suggested issues and fixes and can be found in the blog posting but I have included it here to save people looking.
http://studio-central.com/phpbb/view...t=554&start=17
What I have learnt from reading ALL the comments both on the blog and the studio-central posting is that essentially Alesis asked another company to build the PSU section of the monitors amplifier board which resulted in a poor design-
The power supply, apparently, was designed by a different engineering group from that of the rest of the speaker. Their mission was to cut the cost, weight, and size of Alesis power supplies by designing switching power supplies to replace the traditional analog ones. The M1 Active Mk II contains one of the first switching power supplies designed by this team – and, as we all now know, they didn't quite get it right. The power supply is sensitive to spikes in the AC voltage and slowly cooks itself to death.
(Thanks to -Obscuro for the information)
The upshot of all this is, that amongst other issues people have encountered, the main problem seems to be 2 poorly placed capacitors dry up and fail, these being C8 and C35 (see the pictures of the circuit board on the blog link I included).
Since I don't have a ESR tester and C8 and C35 capacitors seem to present the most common problem people have experienced, I would like to try to fix this first.
However to add to the complication Alesis or the PSU manufactures weren't consistent when installing these capacitors and it seem at least two types were used for C8.
220µf 35 V and a 330µf 35 V.
In my monitor C8 and C35 capacitors are the following-
C8- JunFu WJ105 ºC 0304 220µf 35 V green coloured cap
C35- JunFu HK105 ºC 0306 1µf 50 V navy blue coloured cap
I have subsequently discovered from your wonderful forum that JunFu or Jun Fu capacitors are 'bad caps' so my questions are these.
What is the absolute best capacitor to replace these with given their use in a high grade audio monitor and tendency to dry up because of poor placement?
Should I use the same rating capacitors, or would another rating fix the issues better?
Should the capacitor be polarised or non-polerized?
(I'm guessing non as apparently it's apparently AC voltage but I'm really just working with others information as i know so little).
I am considering soldering C8 in on the back of the board to avoid the heat, but as you can see there isn't much room, ideally I would like a replacement component that is the best quality possible, can handle the heat and permanently fix this problem and stop it ever reoccurring.
So far I have found these-
http://cgi.ebay.co.uk/Elna-Cerafine-...#ht_500wt_1154
Will they work? Are they any good?
Can anyone suggest the best cap for the job? Or any other helpful advice?
P.S - Here are some pictures of my units board so you can see for yourself.
http://www.flickr.com/photos/1229014...7624827549078/
Kind Regards,
Joe.
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