Sign in   |  Join   |  Help
Click here to tell us about your new email address

M75 Speakers

rated by 0 users
Not Answered This post has 0 verified answers | 37 Replies | 1 Follower

Piaf
Top 50 Contributor
Victoria, British Columbia Canada
2,476 Posts
OFFLINE
Founder
Piaf posted on Mon, May 22 2017 12:17 AM

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

Beogram 4000, Beogram 4002, Beogram 4004, Beogram 8000, Beogram 8002, Bogram 1602. Beogram 4500 CD player, B&O CDX player, Beocord 5000 T4716, Beocord 8004, Beocord 9000. Beomaster 1000, Beomaster 1600, Beomaster 2400.2, Beomaster 2400.2, Beomaster 4400, Beomaster 4500, Beolab 5000, Beomaster 5000, BeoCenter 9000. BeoSound Century,  S-45, S-75, S-75, M-75, MC 120.2 speakers; B&O Illuminated Sign (with crown & red logo). B&O grey & black Illuminated Sign, B&O black Plexiglas dealer sign, B&O ash tray, B&O (Orrefors) dealer award vase,  B&O Beotime Clock. Navy blue B&O baseball cap, B&O T-shirt X2, B&O black ball point pen, B&O Retail Management Binder

 

All Replies

Dillen
Top 10 Contributor
Copenhagen / Denmark
9,363 Posts
OFFLINE
Founder
Moderator
Dillen replied on Mon, May 22 2017 6:46 AM

You go in through the woofer hole and/or remove the screws at the back.
http://forum.beoworld.org/forums/p/8017/71340.aspx

Martin

Piaf
Top 50 Contributor
Victoria, British Columbia Canada
2,476 Posts
OFFLINE
Founder
Piaf replied on Mon, May 22 2017 4:43 PM

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....)

Jeff

Beogram 4000, Beogram 4002, Beogram 4004, Beogram 8000, Beogram 8002, Bogram 1602. Beogram 4500 CD player, B&O CDX player, Beocord 5000 T4716, Beocord 8004, Beocord 9000. Beomaster 1000, Beomaster 1600, Beomaster 2400.2, Beomaster 2400.2, Beomaster 4400, Beomaster 4500, Beolab 5000, Beomaster 5000, BeoCenter 9000. BeoSound Century,  S-45, S-75, S-75, M-75, MC 120.2 speakers; B&O Illuminated Sign (with crown & red logo). B&O grey & black Illuminated Sign, B&O black Plexiglas dealer sign, B&O ash tray, B&O (Orrefors) dealer award vase,  B&O Beotime Clock. Navy blue B&O baseball cap, B&O T-shirt X2, B&O black ball point pen, B&O Retail Management Binder

 

Piaf
Top 50 Contributor
Victoria, British Columbia Canada
2,476 Posts
OFFLINE
Founder

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?

 

Jeff


Beogram 4000, Beogram 4002, Beogram 4004, Beogram 8000, Beogram 8002, Bogram 1602. Beogram 4500 CD player, B&O CDX player, Beocord 5000 T4716, Beocord 8004, Beocord 9000. Beomaster 1000, Beomaster 1600, Beomaster 2400.2, Beomaster 2400.2, Beomaster 4400, Beomaster 4500, Beolab 5000, Beomaster 5000, BeoCenter 9000. BeoSound Century,  S-45, S-75, S-75, M-75, MC 120.2 speakers; B&O Illuminated Sign (with crown & red logo). B&O grey & black Illuminated Sign, B&O black Plexiglas dealer sign, B&O ash tray, B&O (Orrefors) dealer award vase,  B&O Beotime Clock. Navy blue B&O baseball cap, B&O T-shirt X2, B&O black ball point pen, B&O Retail Management Binder

 

Piaf
Top 50 Contributor
Victoria, British Columbia Canada
2,476 Posts
OFFLINE
Founder

Second photo.


Beogram 4000, Beogram 4002, Beogram 4004, Beogram 8000, Beogram 8002, Bogram 1602. Beogram 4500 CD player, B&O CDX player, Beocord 5000 T4716, Beocord 8004, Beocord 9000. Beomaster 1000, Beomaster 1600, Beomaster 2400.2, Beomaster 2400.2, Beomaster 4400, Beomaster 4500, Beolab 5000, Beomaster 5000, BeoCenter 9000. BeoSound Century,  S-45, S-75, S-75, M-75, MC 120.2 speakers; B&O Illuminated Sign (with crown & red logo). B&O grey & black Illuminated Sign, B&O black Plexiglas dealer sign, B&O ash tray, B&O (Orrefors) dealer award vase,  B&O Beotime Clock. Navy blue B&O baseball cap, B&O T-shirt X2, B&O black ball point pen, B&O Retail Management Binder

 

Piaf
Top 50 Contributor
Victoria, British Columbia Canada
2,476 Posts
OFFLINE
Founder

This is photo 3.


Beogram 4000, Beogram 4002, Beogram 4004, Beogram 8000, Beogram 8002, Bogram 1602. Beogram 4500 CD player, B&O CDX player, Beocord 5000 T4716, Beocord 8004, Beocord 9000. Beomaster 1000, Beomaster 1600, Beomaster 2400.2, Beomaster 2400.2, Beomaster 4400, Beomaster 4500, Beolab 5000, Beomaster 5000, BeoCenter 9000. BeoSound Century,  S-45, S-75, S-75, M-75, MC 120.2 speakers; B&O Illuminated Sign (with crown & red logo). B&O grey & black Illuminated Sign, B&O black Plexiglas dealer sign, B&O ash tray, B&O (Orrefors) dealer award vase,  B&O Beotime Clock. Navy blue B&O baseball cap, B&O T-shirt X2, B&O black ball point pen, B&O Retail Management Binder

 

Piaf
Top 50 Contributor
Victoria, British Columbia Canada
2,476 Posts
OFFLINE
Founder

Last but NOT least, photo 4.


Beogram 4000, Beogram 4002, Beogram 4004, Beogram 8000, Beogram 8002, Bogram 1602. Beogram 4500 CD player, B&O CDX player, Beocord 5000 T4716, Beocord 8004, Beocord 9000. Beomaster 1000, Beomaster 1600, Beomaster 2400.2, Beomaster 2400.2, Beomaster 4400, Beomaster 4500, Beolab 5000, Beomaster 5000, BeoCenter 9000. BeoSound Century,  S-45, S-75, S-75, M-75, MC 120.2 speakers; B&O Illuminated Sign (with crown & red logo). B&O grey & black Illuminated Sign, B&O black Plexiglas dealer sign, B&O ash tray, B&O (Orrefors) dealer award vase,  B&O Beotime Clock. Navy blue B&O baseball cap, B&O T-shirt X2, B&O black ball point pen, B&O Retail Management Binder

 

Dillen
Top 10 Contributor
Copenhagen / Denmark
9,363 Posts
OFFLINE
Founder
Moderator
Dillen replied on Tue, May 23 2017 9:40 AM

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.

Martin

Piaf
Top 50 Contributor
Victoria, British Columbia Canada
2,476 Posts
OFFLINE
Founder
Piaf replied on Tue, May 23 2017 3:30 PM

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?

Jeff

Beogram 4000, Beogram 4002, Beogram 4004, Beogram 8000, Beogram 8002, Bogram 1602. Beogram 4500 CD player, B&O CDX player, Beocord 5000 T4716, Beocord 8004, Beocord 9000. Beomaster 1000, Beomaster 1600, Beomaster 2400.2, Beomaster 2400.2, Beomaster 4400, Beomaster 4500, Beolab 5000, Beomaster 5000, BeoCenter 9000. BeoSound Century,  S-45, S-75, S-75, M-75, MC 120.2 speakers; B&O Illuminated Sign (with crown & red logo). B&O grey & black Illuminated Sign, B&O black Plexiglas dealer sign, B&O ash tray, B&O (Orrefors) dealer award vase,  B&O Beotime Clock. Navy blue B&O baseball cap, B&O T-shirt X2, B&O black ball point pen, B&O Retail Management Binder

 

sonavor
Top 50 Contributor
Texas, United States
2,688 Posts
OFFLINE
Gold Member

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.

 


Piaf
Top 50 Contributor
Victoria, British Columbia Canada
2,476 Posts
OFFLINE
Founder
Piaf replied on Tue, May 23 2017 6:47 PM

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.

Jeff

Beogram 4000, Beogram 4002, Beogram 4004, Beogram 8000, Beogram 8002, Bogram 1602. Beogram 4500 CD player, B&O CDX player, Beocord 5000 T4716, Beocord 8004, Beocord 9000. Beomaster 1000, Beomaster 1600, Beomaster 2400.2, Beomaster 2400.2, Beomaster 4400, Beomaster 4500, Beolab 5000, Beomaster 5000, BeoCenter 9000. BeoSound Century,  S-45, S-75, S-75, M-75, MC 120.2 speakers; B&O Illuminated Sign (with crown & red logo). B&O grey & black Illuminated Sign, B&O black Plexiglas dealer sign, B&O ash tray, B&O (Orrefors) dealer award vase,  B&O Beotime Clock. Navy blue B&O baseball cap, B&O T-shirt X2, B&O black ball point pen, B&O Retail Management Binder

 

Piaf
Top 50 Contributor
Victoria, British Columbia Canada
2,476 Posts
OFFLINE
Founder
Piaf replied on Tue, May 23 2017 6:48 PM

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.

Jeff

Beogram 4000, Beogram 4002, Beogram 4004, Beogram 8000, Beogram 8002, Bogram 1602. Beogram 4500 CD player, B&O CDX player, Beocord 5000 T4716, Beocord 8004, Beocord 9000. Beomaster 1000, Beomaster 1600, Beomaster 2400.2, Beomaster 2400.2, Beomaster 4400, Beomaster 4500, Beolab 5000, Beomaster 5000, BeoCenter 9000. BeoSound Century,  S-45, S-75, S-75, M-75, MC 120.2 speakers; B&O Illuminated Sign (with crown & red logo). B&O grey & black Illuminated Sign, B&O black Plexiglas dealer sign, B&O ash tray, B&O (Orrefors) dealer award vase,  B&O Beotime Clock. Navy blue B&O baseball cap, B&O T-shirt X2, B&O black ball point pen, B&O Retail Management Binder

 

chartz
Top 25 Contributor
Burgundy, France
3,515 Posts
OFFLINE
Gold Member
chartz replied on Tue, May 23 2017 7:16 PM

Hi,

I'd temporalily unsolder the relay and/or bypass its contacts for testing purposes. See what happens then. No risk.

Jacques

Søren Mexico
Top 10 Contributor
Mexico City
5,931 Posts
OFFLINE
Bronze Member

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.

Piaf
Top 50 Contributor
Victoria, British Columbia Canada
2,476 Posts
OFFLINE
Founder
Piaf replied on Tue, May 23 2017 8:10 PM

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.

Jeff

Beogram 4000, Beogram 4002, Beogram 4004, Beogram 8000, Beogram 8002, Bogram 1602. Beogram 4500 CD player, B&O CDX player, Beocord 5000 T4716, Beocord 8004, Beocord 9000. Beomaster 1000, Beomaster 1600, Beomaster 2400.2, Beomaster 2400.2, Beomaster 4400, Beomaster 4500, Beolab 5000, Beomaster 5000, BeoCenter 9000. BeoSound Century,  S-45, S-75, S-75, M-75, MC 120.2 speakers; B&O Illuminated Sign (with crown & red logo). B&O grey & black Illuminated Sign, B&O black Plexiglas dealer sign, B&O ash tray, B&O (Orrefors) dealer award vase,  B&O Beotime Clock. Navy blue B&O baseball cap, B&O T-shirt X2, B&O black ball point pen, B&O Retail Management Binder

 

Page 1 of 3 (38 items) 1 2 3 Next > | RSS