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beomaster 4000 capacitor change

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ALF
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ALF posted on Sat, Jun 24 2017 1:52 PM

greetings all 🌝

Can someone advise me on suitable replacements for the 3 big caps in the BM4000 ?

they are rated at 5000uf 70V/80V:

beolover replaced all three with  5600uF 80V caps.......

would 4700uF 100V work as well ?

thank you for your advice/suggestion

cheers

ALF

 

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Søren Mexico
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If I remember right I put 4700/100 in mine, still working Smile

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

sonavor
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sonavor replied on Sat, Jun 24 2017 10:06 PM

If you go by the tolerance which I believe is 20% then for the original 5000uF value you have a range of 4000uF to 6000uF. I have found a lot of these larger capacitors tend to measure on the low side of their rated value so I usually go up in value when I get a replacement.

John

ALF
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ALF replied on Sun, Jun 25 2017 2:06 AM

Thank you Søren and John for reassuring comments - much appreciated

now work can continue without worrying 🤡

ALF

ALF
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ALF replied on Tue, Jun 27 2017 2:31 AM

Hello John,

just to confirm your experience:

I took my cap tester to the shop and measured some caps of my first choice 4700/100.

none measured more than 4050uF !!

all 5600uF caps measured just over 5000uF 😸

I decided to replace all three big ones at the same time in the hope it would cure my sick right channel......👿

No, it did not and the DBT stayed on bright .....!

the board gets about 59V per channel. I suspected the two power darlingtons MJ25001/3001 but have my doubts as they measure

exactly the same as the other pair in the healthy channel ??

disconnecting the suspect pair and the DBT goes dark!

it is now down to basically compare the left and right channel components unless there is a smarter way ?

cheers

ALF

ALF
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ALF replied on Tue, Jun 27 2017 10:00 AM

At last some good news 😂

By the way, it was the left and not right channel - not that it matters that much in the end.

I kept circling around that pair of output darlingtons - in particular the MJ3001 after testing a range of transistors as suggested in the SM.

after multiple changes of that very transistor and not getting anywhere I finally got lucky and tried another replacement - now it worked!

it looks like I purchased a number of fake parts, or at least dogy ones !

that was the bigger problem solved - the DBT is still illuminated very faint, meaning somewhere

is another smaller devil hiding ?

I noticed the stereo light only seem to come on when tape or other than FM is selected or is it on all the time but very faint ?

there was something similar mentioned in the BM2000 SM apendix about a permanent illuminated stereo bulb ?

both tuning indicators work fine and pulled-in stations are received in stereo sound where available!

looks like some more work and / or even tuner alignment........oh NO !

any words of wisdom are very much appreciated - as always 🤡

ALF

ALF
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ALF replied on Wed, Jul 5 2017 7:41 AM

Hi again,

the BM4000 works minus that stereo indicator, which seem to be on all the time ?

it is not point in messing with the tuner trimmers without having a proper function generator/sweeper.

what is however annoying are the speaker terminals - their contacts are pretty worn and touchy!

i am not sure whether it is wise to drill out the two pairs and find a fitting replacement ?

if someone has any better idea / suggestion please let me hear it 😻

Asside from that issue I am very happy with this model - quite amazing how good these units sound !!!

cheers

ALF

 

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