ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
There is just one layer and 15-16 turns.
I used the pointed razor knife to scrape insulation material away from the wire I had to join. Then I applied a little flux paste and tinned the bare wire ends. After that I bent the loose wire where I could hold the coil in one hand with the two bare wire ends side by side. With the other hand I tinned the smallest solder tip I have and applied a bead of solder.
The first picture shows that first join. It served the purpose of attaching the wires so I could use a little super glue to mount part of the loose wire to the voice coil ring. That glue dries quickly and I could then work on making a better solder joint. The second picture shows as it is right now. The wire is joined together pretty good. I was hoping for a better looking joint but I'm not sure if I want to keep messing with it (I could make it worse). The solder joint does not stick out farther than the copper wire coil so it shouldn't be a problem. I don't have any conformal coating (or can't find it) so I can either order some or use some super glue.
With the wire re-attached I measured the resistance across the driver connectors. I measure 7.2 ohms.
I found my circuit sealer and put a coating over the solder and repaired wire. It looks like the voice coil just lays into the slot of the magnet part and snaps into the plastic frame. Comparing this one to the good one - both measure 7.2 ohms. I am getting sound out of the repaired midrange now but it isn't right....much to faint. When I connect a 500 Hz sine wave to the good phaselink the tone is strong even with the voltage level down around 65mV. The repaired driver is barely noticeable. I can turn up the voltage level and get get better volume but it doesn't sound the same to me as the good one. It definately won't do as it currently is.
So I must not have the driver put back together correctly or there is some other part of it that is damaged. The top part of the coil ring has some clear glue residue. Should the coil be fixed to the rubbery/plastic dome that fits over it? Is that what you are referring to Step1 ?
In this picture...
Is this how the phaselink midrange driver should re-assemble? With the rubber/plastic dome laying into the plastic frame, then the voice coil mounting to the inside of the dome?
Since the side of the ring that meets the dome has residue glue on it I am thinking that is what Step1 meant about the coil and dome coming un-glued. Hopefully that is also the issue with the sound problem.
I won't go any further until I get confirmation but jumping ahead to the next question - Assuming the coil will need to be glued in the position shown in the picture here, Does the magnet part of the driver just slide in and snap into place in the frame? Or should it also be glued? The reason I ask is because the magnet had glue on the area near the terminals.
Yes Sonavor the coil should be stuck to the dome - otherwise the mechanical energy of the moving coil will not be transferred, which sounds like your current issue! Just make sure the coil sits in its little ridge - it has to be absolutely round without distortion. The dome should be glued to the outer frame, then this whole assembly clips onto the rear assembly.
Olly
I glued the coil in the dome and the dome to the frame today. For the coil I used the same clear glue I used for the surrounds. It can take movement but it bonds very fast and doesn't take much for it to hold tight. I used a Q-tip cut in half at an angle. I like the original Q-tip that has a solid paper shaft (not a hollow plastic tube like the newer ones). The paper shaft part is good for mixing glue, applying glue, etc. With just a dab of glue on the Q-tip end, I slowly applied it to the ridge of the coil that sits in the dome. For the dome edge that meets the plastic frame I used some Aleene's Tacky glue - the green bottle type that remains tacky (dries clear). Where the two leads cross the frame to the terminals there was a layer of sticky, blue tinted glue holding the wires in place. That remaining sticky glue always grabs the magnet assembly and tries to pull up the thin wire leads each time I have taken this driver apart. That is too risky to accidentally break the leads I think so I covered that glue area with a coat of clear glue that dries flexible but dry. If I find that I need a little glue for the magnet assembly I will place some around the frame away from the wires.
Here is a picture of the coil, dome and frame assembly waiting to dry.
Once the coil, dome and frame assembly is dry I will snap the magnet base assembly back in place in the frame and hopefully have a nice sounding midrange driver. Here is a picture of the magnet base assembly (for lack of the official terminology).
Success. I completed the re-assembly of the midrange driver tonight and it works. The tone appears to same as the other midrange now. I am glad I use the green bottle Aleene's (Tack It Over-and-Over) Tacky glue on the dome lip that mates with the plastic frame. To get the voice coil into the magnet base I needed to have the dome and coil assembly where it was easier to move around than when it is flat against the frame. Once I got the coil into the base correctly I was able to snap everything together and the tacky glue still has tack to seal the dome to the frame.
So as of now, seven of the original eight drivers are ready to go. The one 8 inch driver needs to be replace. Both crossovers need to be recapped (I have Dillen's kit for those). I will make sure the inductors on the crossover PCBs are securely mounted. After that I should be able to give the speakers a listen. The other tasks will be cosmetic - restoring the look to the cabinets, maybe repairing the scratches to the midrange/tweeter housing trim and possibly (long shot) restoring the missing top grill panels. I'm not overly concerned with the grill covers as others have pointed out these speakers look good with the covers off...but if I find some.
I plan to start on the crossover recap tomorrow.
Congrats John Good Work
Collecting Vintage B&O is not a hobby, its a lifestyle.
Thanks Søren. Here is a picture of the two sets of tweeter and midranges for the MS150.
sonavor: Success.
Success.
Congratulations and well done. I get to call you a "steely-eyed missileman" yet again.
Bloodshot-eyed maybe
Today I finished recapping the two crossover boards. I used a recap kit from Dillen for the job. Here is a before and after picture of one of them.
Here is the other crossover. I placed a bead of Aleene's Fast Grab Tacky glue under each electrolytic capacitor I replaced. I also used some of that glue to shore up the inductor mounting to the board.
It's a great day outside today. I started to get things in order so I can assemble some working MS150 speakers. Since I need to borrow one 8 inch woofer from my S120.2 speakers I pulled one of them down and opened it up. Here is one of my S120.2 speakers with the grill covers and bass port grill removed.
A couple of things came to mind as I re-examined my S120.2 speakers.
One, I could steal the round plastic trim piece on the tweeter and midrange from one of the S120.2 cabinets and use in place of the scratched one on the MS150 cabinet. The thought there is that I have the grill covers for the S120.2 speakers so the trim piece can be hidden. I don't have the top grill cover for the MS150 speakers.
The second thing was the S120.2 three inch midrange driver. After working on the MS150 midrange I now notice that the S120.2 midrange dome is not the plastic material that the MS150 has. I looked up a couple of pictures on Beoworld of other people's S120.2 midrange and those domes look like the MS150. So I am wondering if mine are a repair or a change in manufacturing. Both of my S120.2 midranges have the same black domes.
Looking at the inside of the S120.2 I can see that the 8 inch woofer is the same as the 8 inch woofer in my MS150. The 3 inch midrange appears to be the same too so the difference is in the dome. Does anyone know if the domes changed and came like mine are? Or are my two S120.2 midrange drivers likely a repair?
Here is a picture of the S120.2 inside. The top picture is the 8 inch woofer. The middle picture shows the tweeter and 3 inch midrange. The bottom picture is just the 3 inch midrange. From the inside it looks the same as the MS150.
Your speakers are not S120.2, they are MC120.2.
Beovox S80, S120, M150 and MS150 came with midranges where the domes were made out of plactic material.
Beovox S80.2, MC120.2, M150.2 and MS150.2 came with midranges where the domes were made out of fabric with some sticky material on it.
So your MC120.2 are 100% original.
- Dennis
Cool, thanks Dennis. If I would have read more carefully the front of the speakers say MC120.2. I had S120.2 on my brain though so that is what stuck.
Is there any difference in sound between the cloth and plastic domes? Both my S80's & 120's have the plastic domes and IMO mid range can sound harsh at times - I wonder if that would be the case with the different material?
My plan today was to start working on the MS150 cabinets. Setting them up on a workbench outside they don't look all that bad. I am going to start with just a good cleanup before deciding how far to go on any refinishing. The first annoying thing to clean is the duct tape residue on the bottom of the cabinets. I tried a cleaning product I have never tried before called Goo Gone. The orange colored liquid sprays on, then you wipe with a cloth unil the grime is gone. It worked really well as you can see in the picture. I taped off the bass port with some painter's tape just to be safe since I didn't know what all I was going to try on the bottom of the cabinet. I also did the same cleaning procedure to the other cabinet.
I will try and do a listening test once I get the MS150's put back together. I will still have one fully assembled MC120.2 so I can use a mono source to it and one of the 150's to see if I can notice anything.
I forgot to post a before picture of the MS150 cabinet. Here it is. The top looks like I might have to refinish it but I am going to try some cleaner and restorer on it first. On the bottom you can see the awful duct tape remains.
I will have to keep the scratched, circular tweeter/midrange trim piece with the MS150 as it turns out. I tried the one from the MC120.2 and there are differences. They are the same size and the trim piece fits into the front speaker frame perfectly. However, there is a difference in the look on the front and on the molding where the drivers mount. Here is a side by side comparison picture. So much for that idea but I did remove the 8 inch woofer (temporarily) from the MC120.2 so I can assemble my MS150's.
Wow! These speakers sound great. They are as good as advertised. Definately ones that I will keep.
I didn't have much trouble re-assembling them...just took my time and verified with pictures that I had all of the wires hooked up correctly. It's too late and I'm too tired to take any pictures tonight but I will tomorrow. I listened to a variety of music from classical to rock n' roll (Tchaikovsky's Capriccio Italien to The Rolling Stone's Can't You Hear Me Knocking). The MS150's handles it all. My repaired midrange is working great. It is sounds as good as the other midgrange so I'm pretty pleased with that.
Good to hear, that they are working! I'm dying to hear mine!
My MS150.2's are ready to be "rerubbered", and I think I will be receiving the rings next week. I ordered rings from Good Hifi. I have dealth with Good Hifi before, and the service has always been great. I've also ordered a capacitorkit from Dillen, which I also think I will be receiving next week. So if all goes well, they should be done before next weekend!
That is where I got my parts too.
In case you haven't opened up your MS150 cabinets before...
When you open the speaker cabinets be aware that the two wires from the cabinet speaker terminal to the crossover board does not provide much slack. So after you have removed the screws for the cabinet front, carefully turn the front on its side keeping the middle part of the front across the middle of the cabinet (wood part). While turned on its side that way you should have plenty of slack to remove the connection wires without them yanking off on their own. As you can imagine the front of the cabinet with the drivers all in place is kind of heavy and will be lopsided so keep a firm grasp. It might be easier to lay the speaker face down on some pillows and lift the wood cabinet back off. By itself the cabinet is lighter.
If you are replacing the surrounds on the 8 inch drivers be careful with removing the sound dampening tube that is attached to the back. I would remove the dampening material from the tube and disconnect the two wires from the driver terminals first. Then, after you remove the four driver lock down fasteners try and gently lift the tube from the back of the 8 inch driver frame. On mine the black plastic ring that fits in the tube likes to come off so I would get it started using a small flat head screwdriver.
Have fun. The end result is very rewarding.
Here are pictures of my reassembled and fully functional MS150 speakers. I don't have a set place for them in my house except for my workshop area and it is too messy to take a picture right now. So I set the speakers up outside for these speakers. I decided to use the metal stands seen in the photograph for these speakers instead of the M100 stands I have because it is easier to lift these speakers and move them without stands attached. These stands work really well. The subwoofer port on the bottom is unobstructed and the speakers sound really good.I am still breaking them in with various forms of music I like. This part is the fun part when I can just sit back and enjoy the sound...and rest my back from carrying these speakers outside and back in.
Thanks for the guide. I have allready had them opened, and it was pretty straightforward as I knew how to do it from my experiences with the Beovox MS150's I had a few years back.
A few pictures of the drivers before and after removing the old surrounds:
I will post the last pictures of the progress with my MS150.2's in the "What are you working on now?" thread.
Well look what arrived in the mail all the way from Denmark. Dillen was able to source me a pair of 8 inch replacement drivers for my MS-150 speakers (thank you very much). These are drivers he put new surrounds on already. It will probably be this weekend before I can install these and put the borrowed 8 inch driver (currently in one of my MS-150 speakers) back into the MC-120.2 it came from. I have been listening to the MS-150 pair for a while now and I am very pleased with their performance. They are loud. I am wondering how they will sound when accompanied by the MC-120.2 pair?
I installed the new 8 inch drivers from Dillen in the MS150's today and put the borrowed driver back in the MC120.2. Here is a picture of the MC120.2 and the MS150 after the driver re-install (note: I still haven't put the MC120.2 bottom port grill back in). The speakers sound great. For now this wraps up my MS150 work. I am keeping watch for the top grill covers for the MS150 as mine didn't come with any.
Looking great - and I believe sounding too!
The side-by-side picture reminds me of the CX50-CX100 pair... the bigger of the pair having simply one third more of casework to house another driver. Probably not so in practice
--mika
Can't believe how small those S-120's look compared to the 150's lol!
The next series of pictures compare my original Beovox MS150 speakers (as repaired in this thread) with a second pair that I recently aquired and with a pair of MS150.2 speakers (that I aquired back in December). In the picture below you can see the front drivers and the back of the cabinet for my first pair of MS150 speakers. Note that the back is also rosewood. The second pair of MS150's that I will show following this post don't have the rosewood backing so I am thinking this pair was the first model in the series.
Here are the second pair of Beovox MS150 speakers. The drivers are the same as the first pair but the back of the speaker now has a black panel that is trimmed with a typical Bang and Olufsen aluminum edge. This pair needs to be refoamed, recapped and some refinishing on the wood veneer. The original owner apparently left the speakers exposed to the sun so there is some fading on the wood. In addition, the wood surface does not feel nice and smooth as it should.
Here are the Beovox MS150.2 speakers. The mid-range driver is different from the MS150 pairs. The back is the same black panel trimmed in aluminum. However, this model adds traditional speaker connections as well as the DIN connection. This pair also needs refoaming and recapping. The wood veneer has scratches on the top so it needs to be refinished too. The top, front, left corner also had a chip in the veneer. The previous owner glued it back in place but didn't do that good of a job. I'll show a closer picture of that after this one.
Here you can see the attempted chip repair. I am not sure if I can remove and re-attach it properly.
This picture shows the backs of the original MS150 (on the right) and the second MS150. My first MS150 set could also do with a refinishing but I don't want to tackle that right now.
Wow, three pairs...
I'm still having trouble figuring out where to store the one pair I have!
I guess it sounds pretty amazing when you have two pairs connected at the same time. I had a pair of MS150s and MC120.2s connected to a BeoMaster 8000 a few years ago, and it sounded pretty good if I remember correctly.
Too bad, that I'm out of space - I don't have the BM8000 anymore and I might have to sell the MC120.2s. And my Pentas are back in place, so the MS150.2s stand unused right now.
I hope you'll update us on the progress with refurbishing the new pairs - keep up the good work!
I only have my original pair of MS150's usable right now. The second pair of MS150's and the pair of MS150.2's need refoaming and recapping (crossovers). I have foam surrounds for one pair but I will have to wait as I have a Beogram 8002 project I am in the middle of. After the Beogram, I need to finish building the Classic Audio Tester project that Beoworld member - classic started (here). I was waiting for some parts to arrive on the tester project so I started the Beogram project.
I didn't set out to aquire three pairs of the MS150 series. You Beoworld members out there that have the virus know how that can happen though. Like you I don't have room for them all. I will have to decide which one (or two) to keep. That is one reason I started looking at the differences between them. The real test will be a listening test to compare them. I will keep updating this thread as I work on the new pair.
Speaking of matching up Beovox speakers with a Beomaster - For a while I had my Beomaster 4400 driving a pair of S75 and S45.2 speakers. That combination really sounded good too.
-sonavor
Looking inside the three sets of MS150's I see that the crossover boards are different. Even between the original MS150 pair (with the wood back) and the newer pair. Here is a picture of the crossover board from my first pair of Beovox MS150's. Note: This picture was prior to the recap.
Here is the crossover of the second pair of MS150's. This is the only pair that I can read the type and serial number of. The type is 6411.
Last, here is the crossover of the MS150.2.