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I have a M75 speaker that is "dead," and I need to get inside to try to find the reason there is no sound. The problem is I can't figure out how to GET inside and I don't' want to break anything guessing. I tried from the front and the back, no dice, and the manual wasn't instructive.
So how do to get into this speaker?
Even if I didn't have this dead speaker I still need to remove the woofers and mid-ranges for re-foaming. So how do I do it?
Thanks.
Jeff
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You go in through the woofer hole and/or remove the screws at the back.http://archivedforum2.beoworld.org/forums/p/8017/71340.aspx
Martin
Thank you Martin.
Oddly enough, this is what I already did, BUT I was afraid to push hard enough on the back panel. Even tried a rubber hammer.
I need to remove the woofers and mid-ranges for re-foaming anyway, but now I know how to get in an investigate.
Now I gotta hope that the fault is obvious enough for a layperson to recognize.
Could it possibly have anything to do with the over-ride protection? Had that issue with my MC120.2 speakers and had to bypass the protection circuit as switch are not available. (You might remember all that....)
Opened up the M75 and this is what I found.
I checked the outlet for corrosion but the outlet was pristine. No broken wires, and the caps all look good. I swapped speaker cables just in case, but not the cable.
There is NO sound of any kind, so is there anything else to do other than send the board off for proper testing?
Second photo.
This is photo 3.
Last but NOT least, photo 4.
Piaf: There is NO sound of any kind, so is there anything else to do other than send the board off for proper testing?
Check the safety circuit relay etc.
Hello Martin,
At some point all this intense "hand holding" must be annoying to any B&O maven.Sorry about that.
But as I have no choice but to look stupid (again), where is the safety circuit and how do I test it?
Hi Jeff,Here is the schematic of your M75. It shows the relay (RL1) Martin is referring to. You should be able to physically trace wiring from the speaker DIN jack to the relay.
Thank you John for the schematic. I think I will be able to figure out this issue from here, now that I know to look for the RL1 relay.
I assume I need to test for a "value" after the relay, if so what should I expect to find?
I also assume that if there is no value after the relay that it either needs to be replaced or by-passed. Is this correct?
I have the four speakers out and will take them today to be re-foamed by a local shop.
Hi,
I'd temporalily unsolder the relay and/or bypass its contacts for testing purposes. See what happens then. No risk.
Jacques
just bypass the relay 1-2 in drawing, if you then have sound we know its the overload circuit, you can then try to find the failure comparing measurements and components with the other speaker, this will be technical so maybe take the whole crossover to the speaker shop. Or just use the speaker without overload security
Collecting Vintage B&O is not a hobby, its a lifestyle.
Hi Jacques and Soren,
I am heading over to the local shop late this afternoon (They don't always show up until after 3:00PM) and leave the 4 speakers for re-foaming.
I don't really trust them with electrical work as I saw what they did to my McIntosh cross-overs. The end result was OK, but getting there.... let's just say they are like bulls in a china shop.
I have no problem bypassing the over-load circuit as I had to do this on my MC120.2 speakers.
The plan (for now) as once working the M75's will be mated with my trusty BM 2400.2 and at 25 watts per channel poses little risk of overload to these 75 watt speakers.
Guys,
I tried everything I could to avoid this, proving beyond a doubt how truly stupid I am, at least with electronics. However even my shop in Georgia is not sure, so could someone please tell me by description which "box" is the over-load relay?
If this was a motherboard the numbers are stamped on the board and I could avoid this embarrassment.
I know it is the RL-1 replay but I can't take the schematic and transfer it to the actual board. So from the photo below could someone take pity on me and tell me which box is the one to bypass?
Boy, this electronics thing really keeps me humble!
Thank you Peter!
I was 99% sure that was it, but 99% is not positive. Now I am.
Guys, one more question if you please, can I leave the relay in place and connect wires on either side to bypass it, or do I need to de-solder the relay and run the wires directly?
You can leave it in place, no problem.
Thanks Jacques, that is exactly what I hoped to hear.
Well guys today I decided to bypass the over-load protector and JUST as a precaution, although I marked the speakers numerically, I tested #1 see if I had the correct failed speaker. I was surprised when it played just fine (missing the mid-range and woofer still in the shop.)
Hooked up speaker #2, the one I thought was good, and it is. Both speakers sound wonderful, if bass-less for the moment.
Fluke? Operator error? The relay was "disturbed" in transport? I don't know, but the seller said they both played fine, and indeed they do.
I will offer, as a guess only, that as I left the S45 speakers still hooked up and these M75 surely draw more power, it is "possible" the S45's were sufficiently louder that I missed one of the two speakers playing. Truthfully I find that hard to believe, bit it is either that or a intermittent fault.Personally, I hope it was a mistake on my part.
In any case embarrassment is easier to cure compared to an intermittent electrical fault.
I hope when I re-install the woofers and mid-ranges that I owe you guys an apology for wasting your time as opposed to another request for help!
Requests from beofriends are always welcome Jeff, and there certainly are no silly ones, alright?
chartz: Requests from beofriends are always welcome Jeff, and there certainly are no silly ones, alright?
Agree With Jacques, and the stupid relay maybe got hung up during transport and when you started disassembling it came loose again, who knows, lets be happy that it works
Søren Mexico:Requests from beofriends are always welcome Jeff, and there certainly are no silly ones, alright?
Thank you Jacques and Soren, very, very much!
It occurs to me that to get the back panel off I had to really POUND on the panel. I mean it really resisted coming out. So since we are taking about a basic relay all that vibration might well have caused it to reset.
It has been said often here on BeoWorld how fantastic the help is, and it is, but also the feeling of genuine friendship. I really appreciate both! Thank you!
This is the before:
This is the after, a little better, eh? (So Canadian)
And now the "finished product," woofers and mid-ranges re-foamed, frets renewed, veneers cleaned to perfection, and the intermittent "dead" speaker functioning properly (for the moment)..... for a comparison between the S75's and the new M75's.
In truth, there is NO comparison, but after 6 weeks of aggravation, I am so happy to place the M75's with my ever trusty Beomaster 2400.2 and move my much appreciated S75 speakers to the dining room for my FINALLY functioning Beomaster 1600. (That only took 5.5 months!)
The broken fret post (courtesy of the seller) has a replacement in the mail (thank you Martin) so this is finally coming together.
I am thrilled with these M75 speakers and thank everyone for their Beohelp!
Ah, what the heck, just one more photo.
Guys, on all my photos (I don't seem to know how to re-size them properly for this format) but if you click on them, you can see the WHOLE picture.
Buying these speakers was such an adventure, from the ferry ride to Vancouver, the odd seller, the dead speaker, the unnecessarily protracted re-foam repair, and the accidental "repair" of the dead speaker.
Bottom line, I am simply THRILLED that this came out so utter GOOD in the end. (It doesn't always....)
Hi Jeff,
They look good.
How do you like the French-made Audax tweeter then? This has always been a favourite of mine, having used it in the past (from circa 1980). It was used a lot this side of the Pond.
chartz:How do you like the French-made Audax tweeter then? This has always been a favourite of mine, having used it in the past (from circa 1980). It was used a lot this side of the Pond.
Hi Jacques,
How do I like the French-made Audax tweeters? Where do I begin?
First off, on paper the M75 speaker is nearly identical to the S75. True the M75 is a bit larger, uses different speakers, and mother of Jefferson Davis, that massive cross-over network, but still.....
I was astonished, even shocked by the difference in sound quality. We are talking a modest 8" woofer, but within the first hour of serious play, I adjusted the BM 2400 to neutral for the bass, as these speakers do not require the boost S75's did.
In direct answer to your question, i just LOVE the sound of the tweeters.
A lifetime of audio "abuse" has left my upper range "in question." With the S75 speakers especially at volume the tweeters (to me) sound crackly as if broken. Think of shaking a container filled with broken glass and that's what it sounds like to me.
The M75's are different, same LP, same amp, but the broken sound is not there. So I have a SPECIAL appreciation for your French tweeters.
The clarity in the upper range is remarkable, the mid-range accurate, and commendable bass.
In short, what is not to like?
Did that answer your question?
I decided based on your enthusiatic response to put on the GOLD STANDARD of records, Bette Midler's "For the Girls" album on my remote controlled Beogram 4004 with its NOS MMC20CL cartridge and see what these M75 speakers can really do.
Soren: I hope you are paying attention as I am listening to "your girl!"
Wow, these speakers are amazing, truly remarkable, and clearly MUCH better than expected. The realism is outstanding....... must be those French tweeters!
Of course the M75's are the junior version of the M100's, so I am tantalized at thought they would be even more impressive..... and of course, the Holy Grail, MS150's.
Isn't it great to have a goal? Something to look forward to? You bet it is guys!
In the mean time I could not be happier with these M75 speakers, from the bookmarked veneers to the magnificent sound quality.
I know the feeling.
The last time I was so excited (B&O speaker wise) was when I got my beloved M70s. Truly amazing speakers, in heavy everyday use chez Jacques. There was a very good review in Hi-Fi News some time earlier this year about them by Tim Jarman, and I can say I fully agree with him. The M75s being B&Os next effort after the M70s, they should indeed be something quite special.
I envy you.
Jacques,
It is official, I am "over the moon" for these speakers. The flawless upper range, the accurate mid-rang, and that delightful DEEP all encompassing bass.
While you sir, are the quintessential gentleman.
Jeff I can understand your enthusiasm, I feel the same with my M70s ( as Jacques) I have started using Bette as my "test" LP.
I listened to Søren Hammers MS150s i Aarhus DK, and I think maybe I can squeeze them in somewhere, but as far as I remember the deep bas wasnt any better than the M70s, but I may be wrong. It will take a very good pair of speakers to beat M 70s or M75.
Just got the latest Chuck Berry LP " Chuck" in the door yesterday, some tracks I never heard before, good quality vinyl, recommend it
Keep them coming Jeff, as the Saint I enjoy your posts
Saint Beogrowler:Jeff, your enthusiastic writings and posts are so enjoyable and refreshing to read. I'm glad your hard work and patience paying off.
Why thank you Peter, you are most kind.
These speakers have been a bit of a challenge but with the amazing BeoHelp, it has proven to be more than worthwhile.
When I agreed to purchase these speakers I had NO idea how remarkable they really, really, are.
Søren Mexico: Jeff I can understand your enthusiasm, I feel the same with my M70s ( as Jacques) I have started using Bette as my "test" LP. I listened to Søren Hammers MS150s i Aarhus DK, and I think maybe I can squeeze them in somewhere, but as far as I remember the deep bas wasnt any better than the M70s, but I may be wrong. It will take a very good pair of speakers to beat M 70s or M75. Just got the latest Chuck Berry LP " Chuck" in the door yesterday, some tracks I never heard before, good quality vinyl, recommend it Keep them coming Jeff, as the Saint I enjoy your posts
Hi Soren,
M100's or even better still MS 150's ARE my goal, but at US$151 I couldn't resist these M75's. Good God, I am so glad I didn't! (If I ever find another pair, I am buying them sans doubt.)
The bass on these M75's is hard to describe, but it is full, complete, AND realistic. Soren, you know me, if I turn the bass down, it has GOT to be good!
Now as for the Chuck Berry LP, could you provide a bit more detail? I love Chuck Berry and would really like this new album.
Thanks for the kind words. I know I "frustrate" you from time to time as I lack your electronic talent. But you know we share the same enthusisam for B&O products.
Soren, I probably don't need to say a word, but thank you for the BL/BM 5000. You might not be surprised to hear that I have not used them once in 3 days due to the M75's.
Piaf:It will take a very good pair of speakers to beat M 70s or M75.
OK guys,
This begs the question, empirically what IS the difference between the M70 speaker and the M75? If one owned both, could you tell the difference? And why, please?
Inquiring minds and all that .....
I have both the M70 and M75 (amongst M100, S45.2, S80.2...). There is a big difference in sound quality to my ears between both speakers. Can't understand some comments that praise the M70 to heaven. The M75 is much better to me. Better details, better midrange and definitely better highs. It sounds like the M100 with less bass. I had them connected to my Beomaster 8000 today so was able to switch between both sets easily. Normally I have the M75 connected to my Beomaster 6000 quad system, but this unit is a bit underpowered to get the most out of it. Having said all this, my favourite B&O speakers for day to day use are still the S45.2. Amazing sound stage, dynamic and crystal clear and still enough power to handle a normal living room.
Forgot to mention, but the design between the M70 and M75 is very different a well. Look at the pictures...