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Beomaster 1001 , how can I take it apart ?

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SebaLele
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SebaLele posted on Sun, Mar 10 2019 11:53 PM

Hello ,

in my recent addiction, another B&O has been found .

This is a lovely BM1001 .Was very dirt inside .

I did the usually check , power supply , bias  and after fixing some dial cord problem and broken lamps I have to clean volume  and tone pot . 

These need a deep control cause they shout louder casually .

I take off the bottom to service but seem very hard to lift the upper part .

I have the alluminium panel dial scale on hands but I can't take off the other upper panel .

I read the service , on pg 20 (or 43) there is a drawing ... seem there is no way to get access to pot without take it fully apart .

Tomorrow I'll post some picture to show better.

Do someone been working on this model ? 

Many thanks for your comment

Gabriele

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W.Frankenberg
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hello, to the potentiometer you get up very quickly, the aluminum cover with the sliding gliders is just plugged

in and can be easily levered up with a little feeling!

To get to the attachment of the scale pointer, you have to take the unit a little more apart!

Unscrew the three screws on the floor (please check the service manual), now you can open the device like a book☺!

The aluminum plate with scala is held by 4 screws at the corners, the movable scalene pointer is clamped to the scalp rope with 2 screws.

wilfried

SebaLele
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SebaLele replied on Mon, Mar 11 2019 10:30 PM

 

Bingo ! great Wilfried !

I was little dissapoint about ... looking at the drawing for long  but I didn't understood .

Just plug in ! I was afraid to break it .

I was able to take off the plate with scala . OK now is naked .

 I add some picture , may be useful for others 

completely apart

to remove plate with keyboard 

1.screw

2 .just turn this screw  a little 

 

Last pull off the left end

this is the tone panel as Wilfried said ; just pull off 

 

Thanks ,

I'll be back with the restore

Bye

Gabriele

SebaLele
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SebaLele replied on Mon, Mar 11 2019 10:31 PM

W.Frankenberg
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hello Gabriele,

Thank you for the picture documentation of disassembling the beomaster 1001 (1200).

I had not indicated the small hidden screw to stabilize the key unit; in all of my dismantled Masters 1001 and 1200

it was no longer available except for one.

Your Beomaster looks visually good and has a complete scaler (with wheels ?).

But tell me, why did you solder out the board with the DIN sockets?

 

Your workbench equipment looks professional, everything you need is there!

wilfried

SebaLele
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W.Frankenberg:

I had not indicated the small hidden screw to stabilize the key unit; in all of my dismantled Masters 1001 and 1200

it was no longer available except for one.

yes , but can be view , I'll take a better picture .

W.Frankenberg:

Your Beomaster looks visually good and has a complete scaler (with wheels ?).

But tell me, why did you solder out the board with the DIN sockets?

Yes look good , just some number on volume panel are  shaded .

I take off the din board to have access a died helko : start to ruin the pcb.. was little humming on tape.

So I start a total recap : every time I replace the caps give a test , and start another pcb 

recap fm board >test OK

recap preamplifier board + Output caps > test OK

recap main amp / power suplly : check....NO FM 

just normal noise , like no input plug to the source...

Damn ..

Power supplies are fine just  -18V on big cap(C467) differ from -23V on sch.

when fm or p1-3 button are pressed dc voltage appear on fm module with right value , but I can't not see any oscillation on module and neither on output of fm module . Here should be in AF .

I suspect for a problem on switch board . There a 20cm bus where switch are soldered ; over this pcb there is a layer a sort of plastic pcb for to get a sord of dual layer pcb ... look at pic sorry for my english.

 

I want check the solder point on that pcb .

No one experieced ?

Ciao

SebaLele
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SebaLele replied on Tue, Mar 12 2019 10:00 PM

Forget . but  very important ...

the amp sound very good from tape input !

W.Frankenberg
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hello gabriele,

I assume that FM was ok before the recap.

If the audio signal on TAPE and PHONO is well reproduced, you can already have no error in the preamp in the power amplifier and in the power supply produced.

I do not believe that on the plastic board of the Feh

If you switch on FM, P1, P2, or P3, actually only the control voltage for the ZF board and the FM tuner will be switched!

Now can the tuning voltage reach the diode tuner, can it be adjusted correctly?

A simple (stupid) question: does the FM bulb light up its brightness?

if this is not the case, you will not work zf level if the bulb itself is ok.

If the bulb is lit, at least the ZF stage is working.

Is there at least a background noise?

Do you have a good antenna signal?


did you change the four tantalum elkos on the switchboard when you recap?

could something have happened while soldering there?


You have described that in the power supply the -23V are not correct, you can still adjust the + 33.3V correctly?

I would adjust the voltage and adjustment for FM ZF and Tuner again.


ok, many words, many questions!


By the way, you've saved the preamp board well and hopefully you get rid of the electrolyte well.

On the capacitors you would also without unsoldering the DIN board come, if you had only removed the 6 screws of the rear metal rail.

P.s.. My english come Form Google translater 😂

wilfried

SebaLele
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Lot of information many thanks ,

before another repair-session let see little further :

W.Frankenberg:

I assume that FM was ok before the recap.

If the audio signal on TAPE and PHONO is well reproduced, you can already have no error in the preamp in the power amplifier and in the power supply produced.

correct , input preamplifier and final stage are OK

W.Frankenberg:
I do not believe that on the plastic board of the Feh

Just suspect , When was lit for fist time only p1,2&3 were working . FM just background noise .I played with button on/off and start sound .

but when switch from Px to FM take about 1-2 second before play in "crescendo" arising .Put some deoxit and fixit . But may be false contact again ..

W.Frankenberg:
If you switch on FM, P1, P2, or P3, actually only the control voltage for the ZF board and the FM tuner will be switched!
they serial ....

Yes Wilfried but , if I see on SM  ,when push p1xfm button, they should set the resistor "tuning" R163...167

 

may the common line of these on 100k pot do not close the loop (to R153). I'm not expert in hf ..


 

SebaLele
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W.Frankenberg:

Is there at least a background noise?

Do you have a good antenna signal?

 

Yes for antenna & background noise (like noise on tape in select without any connector , just noise)

W.Frankenberg:

Now can the tuning voltage reach the diode tuner, can it be adjusted correctly?

A simple (stupid) question: does the FM bulb light up its brightness?

if this is not the case, you will not work zf level if the bulb itself is ok.

If the bulb is lit, at least the ZF stage is working

 

these are to be checked , but , what you mean for zf ? I mean Z62 power supply to first module on FM pcb .

W.Frankenberg:

did you change the four tantalum elkos on the switchboard when you recap?

could something have happened while soldering there?

No Tantalum replacement ; checking ok for short on switchboard 

when I solder there I used the FM for two days ; Today I only touch final stage pcb . But anyway I also checked all solder point and" hammer" the pcb .

W.Frankenberg:

You have described that in the power supply the -23V are not correct, you can still adjust the + 33.3V correctly?

I would adjust the voltage and adjustment for FM ZF and Tuner again.

I have checked PS at about 33 V so I left so .

I've never tuned a decoder . I've 100MHz scope and a digital scope (often used as BW  analyzer ) and thd tester . Generator till 10M .

I can easy check the dc value on SM... 

Damn! was working & singing very well

 

Many thanks wilfried for yours precious suggestions

W.Frankenberg
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ok, FM ZF could not translate google correctly😧

This means the IF of 10.7 MHz

The Zehnerdiode in the power supply to the 100k tuning pots but is also very important, it determines the tuning range of the FM tuner, the voltage is not correct here and constantly the tuning range is too high or too low, meaning you can then only stations below 88MHz or received above 108MHz!

 

I noticed there is a note in a service manual Beomaster 1200, there is a modification for the FM area.

in some older devices, no 3.3k resistor was connected in parallel with the STEREO lamp!

If the bulb had blown, it came to the deteriorated and distorted FM playback, up to the failure of FM!

do you have maybe a device from this old series in front of you?

 Then you should check if the STEREO lamp is ok!

No joke I tested it on one of my Beomaster1200 without this 3,3k resistor parallel to the lamp, without the bulb there is no FM reception!

 

Incidentally, I also have a small problem with the STEREO display on the BM 1001; if I switch to TAPE or PHONO the lamp does not turn on, is that the same with yours? On a BM1200 it lights up!

wilfried

SebaLele
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W.Frankenberg:

This means the IF of 10.7 MHz

The Zehnerdiode in the power supply to the 100k tuning pots but is also very important, it determines the tuning range of the FM tuner, the voltage is not correct here and constantly the tuning range is too high or too low, meaning you can then only stations below 88MHz or received above 108MHz!

OK , this is usefull ; I can not check till Sunday but seem as you said . I should  check on R47 (47K) if there any variations tuning throught P1-3 or FM .

I think that is just an open contact or something like .

W.Frankenberg:

I noticed there is a note in a service manual Beomaster 1200, there is a modification for the FM area.

in some older devices, no 3.3k resistor was connected in parallel with the STEREO lamp!

If the bulb had blown, it came to the deteriorated and distorted FM playback, up to the failure of FM!

do you have maybe a device from this old series in front of you?

 Then you should check if the STEREO lamp is ok!

No joke I tested it on one of my Beomaster1200 without this 3,3k resistor parallel to the lamp, without the bulb there is no FM reception!

 

Somewhere I read something about it , now try google for this retrofit

I can not say this is an early version but it's sure related to service manual . 

At first check 2 lamps were ok ( i don't remeber stereo...fm) but it sounded and received fine .Using just a 300ohm dipole .

I'm going to check for stereo bulb and resistor 

W.Frankenberg:
Incidentally, I also have a small problem with the STEREO display on the BM 1001; if I switch to TAPE or PHONO the lamp does not turn on, is that the same with yours? On a BM1200 it lights up!

Now I'm confused , I give a try . Sure that in FM stereo , if I push mono both bulb (mono&stereo ) lite but sound mono . I don't remember with tape/phono . I'll check

Ciao 

Gabriele

SebaLele
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SebaLele replied on Wed, Mar 13 2019 10:04 AM

I'm not in my cave now but looking at the schematic , appear to be ok having both stereo and mono lite when in fm mode with station in stereo and mono pressed but (right) it sound mono .

Otherwise is strange having stereo light ON when you use tape/phono selector .

In this case fm module should not be supplied and so the stereo light .

I have to test to confirm . But should works so , don't you find it ?

 

Gabriele

SebaLele
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SebaLele replied on Wed, Mar 13 2019 10:04 AM

I'm not in my cave now but looking at the schematic , appear to be ok having both stereo and mono lite when in fm mode with station in stereo and mono pressed but (right) it sound mono .

Otherwise is strange having stereo light ON when you use tape/phono selector .

In this case fm module should not be supplied and so the stereo light .

I have to test to confirm . But should works so , don't you find it ?

 

Gabriele

W.Frankenberg
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The diagram shows three lamps from the left :   FM, MONO and POWER (not STEREO !!)!

The STEREO lamp can be seen below in the diagram, it is switched by the TR16!

The FM lamp is power by TR12 and the brightness can be adjust by R157!

The power lamp should be on if power is on, every time!

The mono lamp is on when the mono switch push and give ground to the lamp !

 

wilfried

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