For Friday’s show, we used Alesis monitor speakers that we had in the lab, plus Steve, one of the students, supplied two.
During installation, one of the speakers started winking its blue power light and ceased playing sound, and before the show another did as well. Steve found a Studio Central forum post suggesting that the problem was due to a failed electrolytic capacitor that gets baked by a hot resistor right next to it, and a quick peek inside confirmed that it was a likely explanation and fix.
After unscrewing, the back panel lifts out and reveals the power supply board mounted vertically on a metal shield, and the crossover/amplifier board mounted flat on the panel.
The naughty capacitor, C8 (actually its replacement after I finished), is in the center red rectangle next to the offending resistor. Another bad electrolytic capacitor whose number I forgot to catch is featured near the top of the board. Both of these tested bad with my Capacitor Wizard in-circuit equivalent series resistance (ESR) tester; all of the other electrolytics on the board tested good.
It was simple work to remove and replace the two capacitors on each board, and it brought both speakers back to life. Thank you, forum posts and Capacitor Wizard!
BTW, are electrolytics supposed to look like this?
Two caveats about this repair. First, I should have used 105°C capacitors, but I could only find 85°C caps on short notice, so these will fail quickly and need to be replaced again. At least now it’s known exactly what needs to be done. And second, the forum post suggests moving either the resistor or capacitor to get them further apart, which is a great idea but which I haven’t done yet. I’ve been trying to think up a clever way to stick a little heatsink on a vertically-mounted resistor, which might be a better solution yet.
Before you do that:
1. be sure to check that the fuse is still intact.
2. Put everything back together, and whack the case of the speaker good and hard while the power is on.
3. If it still doesn’t work, the service. I can fix them, and have in the past, if you are interested.
Cheers,
Pappy
“then service” is what I meant.
Cheers
Thanx Pappy, but I’m afraid that getting in touch with you to fix them is not an option since I’m in Croatia.:) I’m such a noob when it comes to these things. It seemed like something that I could do myself and spare some money, but last night I found out from a friend that maybe I burnt the board since i used the 230V solder and I hope that it’s not that case.:( Cheers!
Yeah..I think that’s a bit too far.
Cheers,
Pappy
Thanks for making that clear Pappy mcfae, I wasn’t getting my information anyplace except the sites I posted, since I and many others here are complete amateurs at this, I wanted to raise the issue and make things clearer for people.
So am I right in thinking the striped line on the cap is the marking to which you refer?
Also I am busy making a full list of all the caps on the board, so i can do a full overhaul with a more reliable cap brand, see my posting on badcaps.com.
Much Love,
BlueBlink.
Yes. The stripe is going to have a + or – next to it. That tells you which is end is which. On the PC board, I believe the positive terminal hole is printed with a +. Put + to + and – to -. and all will be well. Do it the other way…and expect a cap to burst…especially the high voltage caps.
Good luck.
i have the same blinking lights problem.
I saw all the comments and know what to get, but when i go online it’s all just a mess of products. Is there a specific link to order it?
Also, on the outside of the carbon fiber subwoofer dome there’s a rubber part seperating it from the body, mine is ripped there. any suggestions for home fix? also the tweeter dome is ripped:/
Hello.
Thanks for all the great advice here, I have a pair of Alesis M1 Mk2 Actives.
One of which is blowing the power lead fuse everytime its switched on.
I have opened it up and found C8 has discharged gunk all over D5, I have now replaced C8 but have not solved the problem.
On closer inspection I have noticed RT1 is badly damaged and has left scorch marks on the board where part of the back of RT1 has blown off.
PLEASE can someone help me by telling me what component RT1 is, ratings etc.? (RT1 is under the on / off switch on the power supply pcb).
Many thanks,
Al.
This is sooooo timely, because one of my Alesis M1′s just started doing the blinkly light thing. Thanks for posting this fix. I’ll get into the speaker sometime in the next few days to see which capacitors potentially popped! Please post a link to any websites that have parts! Cheers!
for Al D.
At 1st glance it appears that the problem is on the power supply board. Try unplugging the connector between the Power supply board and the audio board.. If the fuse holds then the problem is the audio section. I suspect tho’ that if RT1 is fried that you should look at the pwr supp brd. RT1 is a power thermistor. here’s a link to the specs http://us.element-14.com/jsp/search/productdetail.jsp?SKU=72J6710&CMP=AFC-E14OP
Probable cause is a shorted filter capacitor or a regulator IC on the Pwr Supp Brd. This may have been caused by the bad Audio Brd caps or shorted Audio Output ICs on the Audio Brd. Looks like you have some work ahead of you. Start at checking the large caps and voltage regulator ICs for short conditions on the Power Supp Brd. Fix that and if the fuse holds then plug in the Audio Brd and see if the fuse holds. If not you need to troubleshoot the Audio Brd.
I use Digi-Key.com for parts in the USA. You definitely need RT1 but might as well get the other parts on order, too.
Good Luck
RT1= THERMISTOR 10 OHM 2A NTC
Alesis part number 0-22-0100
Thank you for your replies.
I spoke to Alesis uk and they sent me the service manual so i know have a full component list however I cant seem to buy Thermistor RT1 from anywhere. Any ideas?
I have tested for continuity with my multimeter where C8 had leaked, it appears that the track has been broken above D5. There are 2 copper tracks there, the one just above is damaged but still has continuity accross it but the one above that has more damage (when u hold the board up to the light you can clearly see the track is broken) and there is no continuity.
1. Would this have caused the short?
2. Can it be repaired or do i need to buy a new power supply board?
Many thanks,
Al.
Al, could you please upload the service manual? I’ve been searching all over the internet and couldn’t find one. I removed and replaced the C8 cap, and the speaker still won’t work, so I’d like to take a look at the manual.
To repair the broken track just solder a piece of wire between the nearest solder pads the track goes to. A strand from Cat-5 network cable works very well.
Thanks Alan I will try that.
Marvell – Not sure on the legality of uploading the service manual but if you call alesis uk and explain your issue with the speaker they will e-mail it to you, atleast that’s what I did.
Anyone – Does anyone know where I can buy 1 x THERMISTOR 10 OHM 2A NTC without having to spend atleast £20 with Farnell.
@ Al: Since I’m outside of the UK, I’d like to avoid having to call them on the phone, that’s why I asked you if you could send it.:) You can rest assured that I won’t misuse it or do any illegal activities, so if you change your mind, you can send it to marveldabeatbandit@gmail.com. Thank you.:)
Al D
Here is a link to the part from Digi-Key.Com in the US. They ship world-wide. The part is .68 USD so shipping will be the largest expense. Still it shouldn’t be too much.
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=495-2076-ND
They have a chat line so you can get answers immediately.
Thank you Alan, when I searched the Digi-Key site before I couldn’t find this part but thanks to your link I can now order one.
Once i’ve tried soldering some wire accross the broken track and have replaced RT1 I will update this blog and let you all know how it went.
Thank you for your help, it is very much appreciated.
OMG – just tried to order the thermistor which is 1.77usd but the shipping rate from digi-key to the uk is £18.89p (30usd), what a rip off, cant afford that so looks like i’m stuck.
Anyone any idea where i can buy – 1 x THERMISTOR 10 OHM 2A NTC
In the UK???
Hi-
The power went out on one of my M1 MKII monitors, and I’ve been unable to find *anyone* locally to repair it without replacing the power supply, which with parts & labor comes to almost what the unit cost originally.
My question is does replacing the power supply require soldering? The cheapest route for me right now seems to be buying the part separately.
Thanks!
-Susan
Thanks for posting this. I’ve got the exact same problem on one of my MKII’s… and I can see the same cap doming at the top. I’m going to make the repair tonight.
Susan, I’m fairly sure you can replace the entire power supply board without soldering. Replacing the capacitors on the power supply board, of course, requires soldering.
Could someone who’s working on one check whether all the connections are unpluggable and a board swap is a simple matter?
Thanks so much for the reply, Keith! It would be great if someone can confirm it doesn’t need soldering, since I could handle it if that’s the case.
Thanks again-
-Susan
Does anyone know for sure whether the power supply board can be replaced without soldering?
Thanks-
-Susan
http://cpc.farnell.com/epcos/b57153s100m/thermistor-ntc-10r-2a/dp/RE04710?in_merch=New%20Products&MER=e-bb45-00001002,here i have bought rt1
yes,you dont need to solder power board
Hi marek-
“yes,you dont need to solder power board”
Ah, that’s great news, I’ll order it right away!
Thanks very much!
-Susan
Hi Keith-
I replied to your email and there was a problem with the delivery. I just sent it again, so if you don’t get that one maybe you could email me again?
Thanks!
-Susan
Excellent Marek, I have also ordered a few of RT1 from CPC, still £6 shipping but certainly a lot better than nearly £20.
Susan, yes, as Marek states to change the power board there is definately no soldering required.
Hi Al-
Yep, I’ve ordered the part from Alesis. It’s out of stock, but at least this gets the ball rolling!
Thanks-
-Susan
hi everyone,i am trying to fix power board by my self,does anybody have wiring diagram?thanks
Marek, what’s ur email address?
marekpatrovic@yahoo.co.uk
hi,susan what are you gonna do with your faulty power board?it might be usefull for me,if you happy to sell it
Hi Marek-
Sorry not to reply sooner. I’m waiting to hear back from someone who expressed interest in the board, either to repair or buy it.
If that doesn’t work out I’d be happy to sell it to you, but it looks like you’re in the UK? I’m in the US.
-Susan
hi susan ,yes i am in uk,ok have luck with your power board
Hi!
I’ve changed caps, but no luck.
I’m from New York city.
does anybody have wiring diagram?
Or mayby somebody can fix it.
I’ve call Alesis. They ask for the power board alone $100
hi people,i have fixed my speaker(finally) after half year listening music with one only,it happened with weird burning of yellow filler on board near c6 capacitor,i have replaced rt1,d1-d4,q3,q4,q1,u1,r15,it is nice to hear proper stereo metal music
i have the same speaker and it was blown. i opened it up and found the wire came off of the voice coil. is there a way to fix that?
Erin, I’m sorry but I don’t think you’ll be able to repair the voice coil.
Erin- if the wire came off at the terminal strip it may be possible to re-solder it. However, if it came off at the cone, I agree with Keith, that it can’t be repaired.
The technique I use is to put a suture clamp 1/8″ back from the end of the wire(so the solder doesn’t “wick” back along the rest of the wire) , tin it, and re-solder the end to the terminal strip. (use a very low-wattage soldering iron (10-15 watts Max).
Still, before you even try this make sure the voice coil isn’t fried by pressing gently on the cone. If you hear a scratching sound the VC is “toast” and you need a new speaker.
hey,
same problem here with the blinking led. i looked at the C8 but it looks totally fine (not like on the picture above). can it still be broken?
Just want to say THANK YOU for this article!! Succesfully replaced the capacitor and now it works like a charm again. The Christmas is saved!
“i looked at the C8 but it looks totally fine (not like on the picture above). can it still be broken?”
It is very possible. Leakage is only one way in which the bad caps can self-destruct. They can also short internally. Changing out that cap will eliminate it as an issue. It’s recommended, even if the cap hasn’t spewed its contents.
Hi Marek, Al D
I’m trying to fix my monitors so if one of u could send the service manual to andrewvandelay@googlemail.com i’d appreciate that.
Cheers
Andrew
Hi
I was doing a search for the manual and came across this posting. I’d really appreciate a copy too:
zoanne1uk@yahoo.co.uk
many thanks
i replaced c8, worked perfect!
.
for german people having this problem:
http://www.conrad.de/ce/de/product/421967/ELKO-FC-220F35V105C/SHOP_AREA_17434
it’s 32cent
Hi all.
Had my M1 Mk2′s for 5 yrs with no problems, but recently they’ve both been really temperamental as to when they work or not. So instead of forking out 50 GBP or so per PS to bloody Alesis (who won’t even admit there is a problem, or take responsibility for it), I decided to try the fix here.
I’ve no soldering or electronics experience whatsoever, but this turned out to be a VERY simple process, and I would encourage anyone with the same problem to do it themselves. I used Farnell UK for the parts needed.
If you’re worried bout soldering/de-soldering, (don’t be, it’s easier than you think!) there’s loads of threads online guiding you through the basics.
I read over these 2 from Aaron Cake (thanks dude) before starting just to make sure I wasn’t forgetting anything obvious…
http://www.aaroncake.net/electronics/desolder.htm
http://www.aaroncake.net/electronics/solder.htm
So, a MASSIVE thanks to Keith and his electronics blog, without whom I just might have ended up paying Alesis for this service (when they should be offering it for free!), and also a huge thanks to everyone who’s contributed any info and replies, all of which helped greatly.
Yours truly
xx
Hi all ,
I desolder diode D5 in power supply unit. It was broken too. What is name this diode?
In which I repair was broken: 2xC6 (one have too small capacity), C8 , all Greatz rectifire (D1, D2, D3 ,D4), thermistor RT1 10 Ohm 3A , transistor Q1 IRF840.
)
PS
C8 have too small voltage (35V) I think to use resitors R4, R3 5W or 10 W and placed outside board.
Hi all,
I have the same problem as Gareth W, Tim B and Todd Horton (Tim B and Todd Horton’s original C8 was 330uF, but my original C8 was 220uF). I replaced only C8, but fuse blew.
————————————
Just sent this mail to Alesis:
I have Alesis M1 Active MKII Monitors. I bought them in 2003, and in 2006/2009 they stopped working. The temperatures have sometimes been low, and the power sources has varied in quality. In one of the apartments I lived in, the fuse of the house often failed.
The one that stopped working in 2009:
After being turned off for two weeks, I turned it on and the fuse of the house went immediately. I reset the fuse of the house, tried to turn the monitor on again, but the fuse of the house went again. I didnt turn it on for 1.5 years, which is now. I dont remember any symptoms. There might were some but I dont remember at this point because its a while ago.
After some surfing on the internet these days, I saw that a lot of people had problems with these monitors. 90% of the people that replaced the C8 capacitor got the problem solved. I did that myselves too today (50V). I’m pretty sure I did it properly with high quality soldering.
At the same time I did some careful search with my eyes:
-R27,C38,R3,R4 looks brown because of heating. R27 had lost some paint.
-RT1 looks damaged. Is the thermistor supposed to be black all over the place? I saw iron/metal 25% of the surface and that iron/metal looked a little burned and there was a small hole into the core of it.
When I turned the monitor on, I heard a quick (0.5s) low frequency sound. I turned off the monitor, and then turned it on again – no sound. The fuse of the house didnt fail at least. I opened it up and saw that the fuse was gone brown.
Can you please answer these questions:
-What parts should I replace?
-Do you have a schematic/parts list/service manual that can help me along my way?
————————————
Thanks for your help