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Beomaster 4000

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Saint Beogrowler
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Saint Beogrowler Posted: Sun, Apr 3 2016 12:30 AM

This nice Beomaster has its first 4 switches to the left that do not stay latched. I believe it suffered some beotrauma forcing them inward since they are shorter than the rest of the switches by 4mm. Before I tear it's face off to investigate, are there any surprises I should look out for taking the face apart? I've never dismantled a Beomaster of this era and would like to get it back together.
Saint Beogrowler
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Kind of see the descending shortening of the switches

Saint Beogrowler
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Couple caps were replaced with good quality high temp caps at some point. It seems as if some trimpots were replaced too. Runs nice and cool. Sounds great. Should I switch out the orange capacitors too?
chartz
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chartz replied on Sun, Apr 3 2016 1:32 AM

The orange ones (and the grey ones too for that matter) seem to be less prone to failure than the dreaded red ROE ones. I'd replace anyway, for peace of mind.

Jacques

Saint Beogrowler
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Thanks for your response Jacques! In replacing the 5000uf grey filter capacitors, could I use 4700uf? It seems like they are much more common.
chartz
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chartz replied on Sun, Apr 3 2016 10:11 AM
Peter:
Thanks for your response Jacques! In replacing the 5000 µf grey filter capacitors, could I use 4700uf? It seems like they are much more common.

Of course, no problem at all. Choose the ones that fit, even if the voltage is higher. Alternatively, you may use some plastic foil to adapt them. These caps are usually still fine though.

I'd also replace the trimmers whatever they look like.

As for the keys, they indeed seem to have been pushed-in at some point. I would incriminate mishandling.

The fascia is easy enough to remove. Just be careful with the tuning meter. It is less so to put it back in place - the phone socket, bulbs, and tuning indicator all need special care. You'll see what I mean when you have the thing aside!

The switch bank stays in place, fortunately.

Jacques

Saint Beogrowler
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Thank you again Jacques for your help! That helped nicely. Here is what I found:

The bank of switches was indeed bent. Pliers and muscle, not often the most useful tools with B&O but today that's all that was needed. All the switches work as they should. Lamps all light up (for now), now just waiting for the trim pots and capacitors to arrive.

I just finished recapping and wiring a set of Beovox 5700's and this will make a beautiful friend to them. Super excited.

Søren Mexico
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Good job Peter, we are following

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Saint Beogrowler
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Ah thanks Søren, I've referenced your CD50 servo motor repair instructions so many times. So very appreciative.
chartz
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chartz replied on Mon, Apr 4 2016 6:58 AM

Well done Peter! We need more pictures!

When the trimpots are replaced, please adjust as per service manual. Have you downloaded the service manual yet?

Jacques

Saint Beogrowler
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Thanks! Indeed I have downloaded the service manual and I have schematic from the secret envelope. Reading ahead as I wait for my parts to arrive, I don't think I understand how to adjust these idle trimmers. My only experience has been with the BM 5000 where it was very clearly described. Where do I attach my leads? Here are the instructions:

This is what I see:

the black trim pots are the 250 ohm currently installed. This is a later model with the added 4 extra trimmers flanking the black ones that the service manual says to not touch, with repercussions being...an unknown silent future?
So anyway, what does the "r/hv" stand for that is mentioned in the service manual diagram? I can't find it referenced in any of my intro to audio component repair books. Still learning every day.

Craig
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Craig replied on Mon, Apr 11 2016 8:11 AM

Peter

Good morning......I will be following your posts closely as I too am about to embark on this same adventure, having acquired a Beomaster 4000 (2406) on ebay for a very reasonable price I thought it was the least I could do to try and bring it back to its previous best. Everything seems to work, front facia is a bit faded by direct sunlight, and on initial power up I get a series of "snap/crackle and pop, this occurs on operation of most of the switches and sliders during operation too, opening the case reveals lots of dust and dirt so the first task will be a blow down with an air duster followed by servisol 10 contact cleaner, if I can get at the switch contacts which are buried within the bowels of the machine! I have received a kit of parts from Dillen which includes a lot more pots than I was expecting, the service manual isn't too clear on the reset values for all these little devils and to complicate the task further I don't have signal generator or scope, so some of the pots may have to stay original......however I will post pics of this adventure and hopefully we can swap horror stories as we both progress

Saint Beogrowler
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Hopefully our stories will be of continued success and not horror! I ordered replacement pots for all but I only plan on replacing the 2 bias current pots since I also lack the proper equipment for setting the others. I am on vacation In Texas right now and look forward to returning home to a mailbox full of components. Until then I'll be looking forward to some pictures!

Steve at Sounds Heavenly
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Hi Peter,

I've just checked in my loft and I still have my old UK-spec Beomaster 4000 from many years ago (slight damage to case, electrical condition unknown, but all switches working).  Please let me know if you are interested in a "donor amp" at a very reasonable cost and I can get the switches and other parts checked out!

Kind regards, Steve.

Steve.

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Sounds Heavenly are proud to sponsor BeoWorld!

Please check out my YouTube channel at https://youtube.com/soundsheavenlycables

Saint Beogrowler
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Thanks Steve! I'm imagining shipping this heavy baby to the US will be exorbitantly expensive. Maybe if the cabinet isn't too damaged this could be a good candidate for a restoration?
Søren Mexico
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r/hv is the color of the wire, in Danish rød/hvid, English is red/white

Collecting Vintage B&O is not a hobby, its a lifestyle.

Steve at Sounds Heavenly
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Hi Peter,

I suspect shipping a 10Kg amp from England to USA would cost about £60 GBP or $90 USD - I may get around to restoring it one day but life is so hectic that I'm happy for it to go to a good home if it is of use to a fellow Beoworlder.  Please let me know if you would like more details and photos of the amp.

Kind regards, Steve.

Steve.

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Craig
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Craig replied on Thu, Apr 14 2016 9:31 AM

Peter

As I'm located in the UK this may be something I would be interested in.........what sort of remuneration would you be looking for should the unit change hands ;¬)

Craig

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Craig replied on Thu, Apr 14 2016 10:12 AM

Craig:

Peter

As I'm located in the UK this may be something I would be interested in.........what sort of remuneration would you be looking for should the unit change hands ;¬)

Craig

Oops.....should be asking Steve this question, sorry Peter

Steve at Sounds Heavenly
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Hi Craig,

No problem!  If you can please send me a PM with your email address (or contact me at www.soundsheavenly.com with your email address) then I can email you some photos of the amp.  Once you have seen the photos, please feel free to make me an offer! Smile

I will get it set up this morning to check everything works and report back.  If you would like any more info, please feel free to ask.

Kind regards, Steve.

Steve.

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Founder of Sounds Heavenly Cables and Brand Ambassador for Bang & Olufsen

Sounds Heavenly are proud to sponsor BeoWorld!

Please check out my YouTube channel at https://youtube.com/soundsheavenlycables

Saint Beogrowler
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Great! Craig, I'm glad you're interested in Steve's BM4000. I've have way too many projects going right now and I only have one 240v to 120v stepdown transformer.
Steve at Sounds Heavenly
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Thanks guys,

The Beomaster is packaged up and on its way to its new home!

Kind regards, Steve.

Steve.

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Founder of Sounds Heavenly Cables and Brand Ambassador for Bang & Olufsen

Sounds Heavenly are proud to sponsor BeoWorld!

Please check out my YouTube channel at https://youtube.com/soundsheavenlycables

Saint Beogrowler
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Looks like I will be learning from my mistake here. I have some loud buzzing through my headphones. I had reversed the polarity on one of the replaced capacitors in the output board, left channel 4.7uf/63v number 511.

Here is what I've done; preamp and output board electrolytic capacitors replaced. Big filter caps changed since one was leaking. I was powering up for the first time since recapping in order to test the idle current before replacing the trim pots. It sounded ok but was buzzing even with volume low (that means output board?) and I started smelling something warm. Unplugged, double checked all my work and found the reversed capacitor, replaced it. Restarted, no smell but buzzing remains when radio and tape inputs selected.

So, how do you diagnosis from here? Should I remove and test the components immediately before and after the wrongly inserted cap in the circuit? Or could the buzzing related to something other than my wrongly inserted cap?

Søren Mexico
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Buzzing in both channels and only radio and tape ?

Collecting Vintage B&O is not a hobby, its a lifestyle.

Saint Beogrowler
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Buzzing in both channels equally. In all modes, phono, tape 1,2 and radio stations but I've only tested music in tape 1 and FM. Buzzing increases with volume increases.
Søren Mexico
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Did you test with speakers connected

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Saint Beogrowler
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Yes. Still buzzing. Sorry about the delay, I had to go eat tacos.
Søren Mexico
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Work the ambio and speaker 1-2 switches several times and check again for differences speakers 1-2

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Saint Beogrowler
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Still no luck. Worked the switches many many times. Tried speakers in 1 and 2, reversed Left and Right. Tried different inputs. Still the same 80-100hz buzzing. At volume over 5 the buzzing starts to pulsate.

The capacitors I removed when I tested them with my capacitor tester were all above their values by at least 10%, all except the leaking 5000uf. Would that have any influence?

Saint Beogrowler
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Buzzing also gets louder when an RCA cord is inserted into the tape 1 sockets regardless of which output switch activated.

Also, FM is much louder than it was before I stared this recap. It was louder than other inputs but is now very loud at volume level 2 whereas tape 1 is at a comparable volume at level 5 and the trimmers for adjusting this in the preamp work but not nearly enough.
Søren Mexico
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If you have all the power supplies at the correct voltages and the idle current adjusted, the buzzing coming with all sources I would suspect the power supply or anything before the preamps

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chartz
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chartz replied on Wed, Apr 20 2016 8:36 AM
And the idle current will be way off because of that buzz, if you hear it with volume zeroed. Is it the case?

Jacques

Saint Beogrowler
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Solved! 1 of the dozen or so wires connected to the central filter cap negative terminal was not making contact and a ground wire coming off the preamp board was not making consistent contact. So two grounding issues rather than my reversed capacitor were the problems.

Thank you for all your help in asking questions to help guide me in my thinking.

Søren Mexico
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Congrats Peter, time and time again I stare myself blind with failures like this, good job finding it

Collecting Vintage B&O is not a hobby, its a lifestyle.

Craig
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Craig replied on Fri, Apr 22 2016 12:35 PM

Just at this point on my own project, waiting for 3 off new caps to be delivered......I feel compelled to say that loading up one capacitor terminal with no less than eleven connections is a bit excessive.....little wonder one connection was weak.

ALF
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ALF replied on Tue, Mar 14 2017 1:04 AM

Hi peter,

in case it still is a mystery:  hv is the red-white twisted wire at the bank of  4 wires and r is the red wire in the bank of 4 wires  on the center right hd side.

cheers

ALF

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