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Beogram 8002 Repair

This post has 347 Replies | 13 Followers

Egomon
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Egomon replied on Thu, Mar 3 2016 8:32 AM

Hi. I recently  bought a Beosystem 8000. I'm very new to the Bang Olufsen world. Had previously beomaster 1900. I'm good with soldering but not very good with electronic stuff.

Well I have a similar problem with my Beogam 8002 as  user Sanovar on page 15 in the same thread : the problem is all so in youtube linked here: 

https://www.youtube.com/watch?v=mLARySrPGv8

And the base platter with cartridge is vibrating strongly, after lubrication it got better but still it is very bad.

I played around with buttons and got it to work ...after like 15 minutes or so, and then it worked correctly. But after sitting there on stand by the problem came back! The back two numbers on the screen are flashing whats indicate that the Beogram is not able to get to right speed.

I read the thread from beginning til end and I opened the Beogram up and re lubricate bought the threaded shaft and and the base rotor as well according to the suggestions here on thread.

 

I think that I have to replace all the  capacitors to get it right. As said i'm not good with electronics but good wit soldering. But first I want to ask here if perhaps someone has the similar problem and has some better solution for the problem I'm having

 

Best regards

 

Egon

RAJOD
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RAJOD replied on Thu, Mar 3 2016 8:50 AM

It sounds like you need to replace the caps.   Sonavar has done a very nice job detailing this in case you want to do it on your own.

I own 4 of these tables and one of them started to do vibrate like that.  It has nothing to do with lubrication.  It has to do with improper electrical signals being presented to the eddy current magnetic drive device.   

My guess is some of the electronics have drifted out of spec.   Once in spec that turntable is the best.

Egomon
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Egomon replied on Wed, Mar 16 2016 3:41 PM

Little update. I re-caped the unit and re-soldered the bad's for any loose connection. get a nice respond from the needle, it works and every button works as should. But the vibration of the platter still remains. I cleaned the connections and re-lubricated everything that's needs to be re lubricated. Oh and the last two digits flash still what indicates that the platter does not get speed it needs. I'm totally out of ideas what to do next. 

Does anyone has the same problem and how you solved your problem?

 

Regards

 

Egon

RAJOD
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RAJOD replied on Wed, Mar 16 2016 7:12 PM

I have two working 8002s and one with that vibration issue.   My guess is you missed something.  Its not getting the correct power to those magnets or it would not vibrate.    Did you read Sonavars rebuild?   I think he went over the path leading to the magnets.  

If I ever get around to fixing mine I will post what it was.

cforeman
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cforeman replied on Thu, Apr 21 2016 4:02 PM

Hello, were do u buy this tool ?

 

sonavor
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sonavor replied on Thu, Apr 21 2016 4:07 PM

cforeman:

Hello, were do u buy this tool ?

 

Which tool? This one?

ALF
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greetings John,

I am in the middle of fighting my BG8000, showing various problems.

looking at your pic from inside the MPU box I see the red and blue wire going from the small PCB in the right hd corner down to C28 - the 47uF cap -

however it seems to be connected differently to my BG8000.

look at how my red and blue wire is connected to the 47uF cap !!

have a look at the uploaded pic of mine - would you care to comment ?

BTW, I measured those voltages across my transformer and get basically the same readings !

the 5VDC rail has been re-established but the +/-15VDC is missing - I am waiting for some TIP-32 replacements.

cheers

ALF

sonavor
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sonavor replied on Sun, May 14 2017 8:29 AM

Hi Alf,

I would really you rather post this question under my Beogram 8000 Project as the post you made is for the Beogram 8002. They are similar for sure but since there is already a Beogram 8000 Project with pictures of these components you are asking about it would be better to put the question here.

Here is my answer to this question on the other thread.

Regards,
John

Dillen
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Dillen replied on Sun, May 14 2017 9:54 AM

Looks to me as if the cap is in the wrong way.

Martin

ALF
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ALF replied on Sun, May 14 2017 12:59 PM

Apologies John,

i wasn't aware in that moment that you had this one posted as well !

but reading through it again delivered the answer as this can indeed to be found in the SM !

best

ALF

 

ALF
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ALF replied on Sun, May 14 2017 1:00 PM

No, cap is correctly connected !

ALF

MrQ
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MrQ replied on Mon, Mar 18 2019 5:54 PM

Amazing details. Looking at the knowledge you have about this turntable, I hope you don't mind asking you a question.

I have a problem with my tonearm. It doesn't move down. Everything works, I press PLAY, the tonearm move to the right position, I hear a 'click', but the tonearm doesn't move down.

Any idea what that could be? I was thinking of taking the cover off and adjusting the weight.

sonavor
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sonavor replied on Mon, Mar 18 2019 6:35 PM

Hi, it does sound like a weight adjustment problem. 

First, you must have a cartridge attached. It sounds obvious but a lot of people try to initially test the a Beogram without a cartridge because they don't want to risk damage to an expensive cartridge if something goes wrong. That's a good idea but pickup an old, non-working cartridge cheap for that type of test.

Second, if there is a cartridge on the tonearm and it still won't drop then check that the tracking force knob is present on the tonearm and attached to the internal weight it adjusts. 

Third, there is a service manual adjustment for the initial setting of the tonearm counterweight. That could have been set improperly and may be way out of adjustment.

One other possibility is that there is some obstruction. You will need to get a service manual and learn how to open the Beogram into service position to check that. It isn't that difficult once you learn the tricks but I would recommend doing some research and preparation before diving in. It is easy to break something if you are unfamiliar with the steps.

-sonavor

rubli
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rubli replied on Sat, Aug 21 2021 12:12 AM

Hello !

 

I have the same problem with the arm lifter. voltages are ok, it just seems that the plunger is "sticky" and take too much time to move.

I have seen the photos, but am unsure how to dismantle the plunger, to clean it, if that is what I need to do.

 

any feedback is welcome

 

thanx

 

sonavor
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sonavor replied on Sat, Aug 21 2021 7:28 PM

To trouble-shoot this type of problem I think it is best to remove the turntable components from the cabinet as I did here.
The components all function when set up like that and you can observe the moving mechanisms that are hidden by the cabinet.

When you have everything opened up this way spend some time studying the arm lowering and raising components from different angles.
Check if the solenoid is moving the arm lowering mechanism (or trying to). Maybe there is a mechanical obstruction.

-sonavor

rubli
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rubli replied on Sat, Aug 21 2021 7:50 PM

Wow, Great photos, and great description of what you have done to this TT, thank you for sharing...

 

I did not see that you removed the plunger from the chassis, I am afraid to do so, in the meantime I "washed" the  central shaft through the small hole that can be seen when the arm is up, with a syringe and isopropilyc alcohol, and a duster spray, some red thing came out. it worked afterwards, but today I was testing it again , and it's sticky again, i guess I have to repeat this procedure a couple of times

thank you so much !, these TT's are a beauty

 

regards

 

Alexander

Dillen
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Dillen replied on Sat, Aug 21 2021 8:15 PM

It's more likely to be the counterweight sticking to the adjustment screw.
A teflon or nylon sheet was introduced to prevent this, but it actually only makes things worse in that the sheet
binds to the end of the adjustment screw more than the counterweight does.
Turn the screw a bit.

Martin

rubli
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rubli replied on Sat, Aug 21 2021 8:36 PM

thank you for your advice, but it's definitely something inside the plunger that is sticky, after applying alcohol, and spraying it out with air, it works like a charm, I did that several times, I'll see tomorrow if it's definitely clean

 

thank you again

 

regards

 

Alex

 

ALF
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ALF replied on Sun, Aug 22 2021 2:36 AM

Hello Alex,

i had the same problem and applied a tiny squirt of Deoxit10 and carefully “hand-operated” the plunger - that worked and 

That issue never showed up again…but be careful not to damage any of those tiny connected wires !!

you could also try a small amount of silicon.

good luck

ALF

968driver
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968driver replied on Mon, Aug 23 2021 3:40 PM

Not exactly a reply, but I need some advise from a B&O turntable specialist.
I have restored my Beogram 8002 the best I could.
The only thing that doesn't work is the auto return function at the end of a record.
The Pause function, where the tonearm moves to and returns from its rest position to the same groove of the pause, works perfectly. This indicates that the counter of the revolutions of the drive shaft is working perfectly.
I don't understand, or am I missing something???
Any help is much appreciated.

sonavor
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sonavor replied on Mon, Aug 23 2021 6:12 PM

I have never seen a Beogram 8000 or 8002 with the problem you describe so I can't advise you on a specific answer/solution for the issue.

Unlike the Beogram 400x series turntables where there is an end stop switch and a run-out groove detection circuit, the Beogram 800x turntables rely on the two position sensor signals to count and know where the arm is. 

If you remove power from a Beogram 800x turntable when the tonearm is out over the platter area...then plug the Beogram back in, it will determine that it doesn't know where it is and automatically returns the tonearm to the home position.  The microcomputer keeps track of the start position and counts the sensor pulse to know where the arm is so the logic defaults to return the tonearm home if the microcomputer doesn't know where it is.

It is interesting that the pause mechanism works and the initial set down position works.

When you have an empty platter and press PLAY does the Beogram 8002 scan for a record and return automatically?

Or is it only the end of record play that you have the problem?
You might have to connect up probe wires to the main board and observe the sensor signals on a two (or ideally, four) channel oscilloscope.
Another thing to try would be a different PCB1/PCB2 set to see if the problem is with the circuit board or the sensors.
I realize those options are not available to a lot of people but it is a suggestion if possible to do.

Otherwise you might have to start replacing parts on a try-and-see basis.

I have had owners send me their Beogram 800x boards for testing so that is an option.  I keep fully working Beogram 8000 and 8002 workbench units handy for doing that. You would have to send me a private message via the Beoworld Forum messaging.

-sonavor

968driver
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968driver replied on Mon, Aug 23 2021 7:59 PM

Hi Sonavor, thanks for your answer.

With an empty platter the 8002 scans the platter and returns the arm to the stop position.

With a record, the platter keeps turning and the stylus stays in the last groove. When I carefully lift the arm and move it about 5 mm to the left (slightly over the record label) then auto return engages, the arm returns to the stop position and the platter stops turning.

The start position is detemined by the microswitch and is correct.

The "Pause" function returns the stylus to the previous exact location.

This is something I cannot understand for the moment.

I made all adjustments of the service manual, replaced all electrolytic capacitors and resoldered the PCB's.

Tomorrow I will connect an oscilloscope to check the optical signals of the arm position sensor.

This Beogram 8002 is in a very good optical condition and I would like to keep it as original as possible.

If no solution is to be found, I can always install an end of range switch to activate "Stop" and auto return.

Best regards, Frans.

 

 

968driver
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968driver replied on Mon, Aug 23 2021 7:59 PM

Hi Sonavor, thanks for your answer.

With an empty platter the 8002 scans the platter and returns the arm to the stop position.

With a record, the platter keeps turning and the stylus stays in the last groove. When I carefully lift the arm and move it about 5 mm to the left (slightly over the record label) then auto return engages, the arm returns to the stop position and the platter stops turning.

The start position is detemined by the microswitch and is correct.

The "Pause" function returns the stylus to the previous exact location.

This is something I cannot understand for the moment.

I made all adjustments of the service manual, replaced all electrolytic capacitors and resoldered the PCB's.

Tomorrow I will connect an oscilloscope to check the optical signals of the arm position sensor.

This Beogram 8002 is in a very good optical condition and I would like to keep it as original as possible.

If no solution is to be found, I can always install an end of range switch to activate "Stop" and auto return.

Best regards, Frans.

 

 

sonavor
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sonavor replied on Mon, Aug 23 2021 9:00 PM

That is good and interesting information.

It sounds like the position counter doesn't reach the return limit on the record you are playing.
Have you tried some different albums?  Ones with different length run-out grooves?  Maybe even test a couple of 45 RPM, 7" records.

If that doesn't reveal any valuable information I am just starting another Beogram 8002 restoration myself. I should be at the stage where I can bench test it soon.
When I get to that stage I will make a point to capture the position sensor signals during the run-out groove.  We can compare the signals.
I have never looked at the control signals during that section as it has never presented a problem.  It will be good to have that information for a correctly operating Beogram 8002.

I will let you know when I have that information.

-sonavor

968driver
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968driver replied on Tue, Aug 24 2021 9:20 AM

Hi Sonavor,

the "no auto return" problem is with all 33 rpm LP's or 45 rpm singles.

I observed the following:

The distance from the center of the turntable spindle to the last run-groove of a typical LP is 53 mm.

(auto return does not happen).

With no record on the platter, the distance from the center of the turntable spindle to the point of auto return is 76 mm.

(auto return at 76 mm from the center of the spindle).

The arm position 1 (junction of R8 and R10) and 2 (junction of R9 and R11) signals are clean square waves with an amplitude of about 3 V.

(I don't know how to insert the oscilloscope picture).

Best regards, Frans.

 

968driver
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968driver replied on Tue, Aug 24 2021 9:47 AM

Now I observed something else that I did not observe earlier.

When the tonearm reaches the run-out groove, no auto return happens, I have to push the "STOP" button to return the tonearm.

If, however, I leave the tonearm in the run-out groove, after about 42 seconds the tonearm auto returns.

Now I am really confused!

 

sonavor
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sonavor replied on Wed, Sep 15 2021 2:43 PM

I posted some oscilloscope photos of a Beogram 8002 servo motor drive signals and the two position sensor signals.  I included a measurement of the Beogram 8002 going through the run-out groove of a record.

-sonavor

sonavor
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sonavor replied on Sat, Oct 9 2021 12:44 AM

968driver:

Now I observed something else that I did not observe earlier.

When the tonearm reaches the run-out groove, no auto return happens, I have to push the "STOP" button to return the tonearm.

If, however, I leave the tonearm in the run-out groove, after about 42 seconds the tonearm auto returns.

Now I am really confused!

 

Here is some additional information regarding the tonearm not properly stopping and returning during the run-out groove.

First, there could well be an electrical issue causing this type of problem.
However, it can also be a simple mechanical issue such as not having a correct or good belt on the Beogram servo motor.
On a recent Beogram 8000 (same tangential arm drive mechanism as the Beogram 8002), I did a restoration where everything appeared to work fine.
All of my tests for the completed turntable passed.  Then, while observing the record play I caught it missing the run-out groove and not stopping (and returning home).  

At first the problem was intermittent but steadily got worse. 
Since all of the voltages and sensors checked out I decided this might be a belt issue.
I changed out the old servo belt (who's source was unkown to me...it was on the turntable when I got it).  The new belt was a Beogram 8000 belt from Martin so I knew it had to be good. 

The problem immediately was gone. 

So in my case, there was a slight poor performance of the bad belt that was throwing the Beogram 8000 off. 

As I mentioned earlier, there certainly can be other types of failures that can cause this error but sometimes, as in my example case, the solution could be simple.

-sonavor

Egomon
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Egomon replied on Thu, Mar 3 2016 8:32 AM

Hi. I recently  bought a Beosystem 8000. I'm very new to the Bang Olufsen world. Had previously beomaster 1900. I'm good with soldering but not very good with electronic stuff.

Well I have a similar problem with my Beogam 8002 as  user Sanovar on page 15 in the same thread : the problem is all so in youtube linked here: 

https://www.youtube.com/watch?v=mLARySrPGv8

And the base platter with cartridge is vibrating strongly, after lubrication it got better but still it is very bad.

I played around with buttons and got it to work ...after like 15 minutes or so, and then it worked correctly. But after sitting there on stand by the problem came back! The back two numbers on the screen are flashing whats indicate that the Beogram is not able to get to right speed.

I read the thread from beginning til end and I opened the Beogram up and re lubricate bought the threaded shaft and and the base rotor as well according to the suggestions here on thread.

 

I think that I have to replace all the  capacitors to get it right. As said i'm not good with electronics but good wit soldering. But first I want to ask here if perhaps someone has the similar problem and has some better solution for the problem I'm having

 

Best regards

 

Egon

RAJOD
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RAJOD replied on Thu, Mar 3 2016 8:50 AM

It sounds like you need to replace the caps.   Sonavar has done a very nice job detailing this in case you want to do it on your own.

I own 4 of these tables and one of them started to do vibrate like that.  It has nothing to do with lubrication.  It has to do with improper electrical signals being presented to the eddy current magnetic drive device.   

My guess is some of the electronics have drifted out of spec.   Once in spec that turntable is the best.

Egomon
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Egomon replied on Wed, Mar 16 2016 3:41 PM

Little update. I re-caped the unit and re-soldered the bad's for any loose connection. get a nice respond from the needle, it works and every button works as should. But the vibration of the platter still remains. I cleaned the connections and re-lubricated everything that's needs to be re lubricated. Oh and the last two digits flash still what indicates that the platter does not get speed it needs. I'm totally out of ideas what to do next. 

Does anyone has the same problem and how you solved your problem?

 

Regards

 

Egon

RAJOD
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RAJOD replied on Wed, Mar 16 2016 7:12 PM

I have two working 8002s and one with that vibration issue.   My guess is you missed something.  Its not getting the correct power to those magnets or it would not vibrate.    Did you read Sonavars rebuild?   I think he went over the path leading to the magnets.  

If I ever get around to fixing mine I will post what it was.

cforeman
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cforeman replied on Thu, Apr 21 2016 4:02 PM

Hello, were do u buy this tool ?

 

sonavor
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sonavor replied on Thu, Apr 21 2016 4:07 PM

cforeman:

Hello, were do u buy this tool ?

 

Which tool? This one?

ALF
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greetings John,

I am in the middle of fighting my BG8000, showing various problems.

looking at your pic from inside the MPU box I see the red and blue wire going from the small PCB in the right hd corner down to C28 - the 47uF cap -

however it seems to be connected differently to my BG8000.

look at how my red and blue wire is connected to the 47uF cap !!

have a look at the uploaded pic of mine - would you care to comment ?

BTW, I measured those voltages across my transformer and get basically the same readings !

the 5VDC rail has been re-established but the +/-15VDC is missing - I am waiting for some TIP-32 replacements.

cheers

ALF

sonavor
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sonavor replied on Sun, May 14 2017 8:29 AM

Hi Alf,

I would really you rather post this question under my Beogram 8000 Project as the post you made is for the Beogram 8002. They are similar for sure but since there is already a Beogram 8000 Project with pictures of these components you are asking about it would be better to put the question here.

Here is my answer to this question on the other thread.

Regards,
John

Dillen
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Dillen replied on Sun, May 14 2017 9:54 AM

Looks to me as if the cap is in the wrong way.

Martin

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ALF replied on Sun, May 14 2017 12:59 PM

Apologies John,

i wasn't aware in that moment that you had this one posted as well !

but reading through it again delivered the answer as this can indeed to be found in the SM !

best

ALF

 

ALF
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ALF replied on Sun, May 14 2017 1:00 PM

No, cap is correctly connected !

ALF

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MrQ replied on Mon, Mar 18 2019 5:54 PM

Amazing details. Looking at the knowledge you have about this turntable, I hope you don't mind asking you a question.

I have a problem with my tonearm. It doesn't move down. Everything works, I press PLAY, the tonearm move to the right position, I hear a 'click', but the tonearm doesn't move down.

Any idea what that could be? I was thinking of taking the cover off and adjusting the weight.

sonavor
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sonavor replied on Mon, Mar 18 2019 6:35 PM

Hi, it does sound like a weight adjustment problem. 

First, you must have a cartridge attached. It sounds obvious but a lot of people try to initially test the a Beogram without a cartridge because they don't want to risk damage to an expensive cartridge if something goes wrong. That's a good idea but pickup an old, non-working cartridge cheap for that type of test.

Second, if there is a cartridge on the tonearm and it still won't drop then check that the tracking force knob is present on the tonearm and attached to the internal weight it adjusts. 

Third, there is a service manual adjustment for the initial setting of the tonearm counterweight. That could have been set improperly and may be way out of adjustment.

One other possibility is that there is some obstruction. You will need to get a service manual and learn how to open the Beogram into service position to check that. It isn't that difficult once you learn the tricks but I would recommend doing some research and preparation before diving in. It is easy to break something if you are unfamiliar with the steps.

-sonavor

rubli
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rubli replied on Sat, Aug 21 2021 12:12 AM

Hello !

 

I have the same problem with the arm lifter. voltages are ok, it just seems that the plunger is "sticky" and take too much time to move.

I have seen the photos, but am unsure how to dismantle the plunger, to clean it, if that is what I need to do.

 

any feedback is welcome

 

thanx

 

sonavor
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sonavor replied on Sat, Aug 21 2021 7:28 PM

To trouble-shoot this type of problem I think it is best to remove the turntable components from the cabinet as I did here.
The components all function when set up like that and you can observe the moving mechanisms that are hidden by the cabinet.

When you have everything opened up this way spend some time studying the arm lowering and raising components from different angles.
Check if the solenoid is moving the arm lowering mechanism (or trying to). Maybe there is a mechanical obstruction.

-sonavor

rubli
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rubli replied on Sat, Aug 21 2021 7:50 PM

Wow, Great photos, and great description of what you have done to this TT, thank you for sharing...

 

I did not see that you removed the plunger from the chassis, I am afraid to do so, in the meantime I "washed" the  central shaft through the small hole that can be seen when the arm is up, with a syringe and isopropilyc alcohol, and a duster spray, some red thing came out. it worked afterwards, but today I was testing it again , and it's sticky again, i guess I have to repeat this procedure a couple of times

thank you so much !, these TT's are a beauty

 

regards

 

Alexander

Dillen
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Dillen replied on Sat, Aug 21 2021 8:15 PM

It's more likely to be the counterweight sticking to the adjustment screw.
A teflon or nylon sheet was introduced to prevent this, but it actually only makes things worse in that the sheet
binds to the end of the adjustment screw more than the counterweight does.
Turn the screw a bit.

Martin

rubli
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rubli replied on Sat, Aug 21 2021 8:36 PM

thank you for your advice, but it's definitely something inside the plunger that is sticky, after applying alcohol, and spraying it out with air, it works like a charm, I did that several times, I'll see tomorrow if it's definitely clean

 

thank you again

 

regards

 

Alex

 

ALF
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ALF replied on Sun, Aug 22 2021 2:36 AM

Hello Alex,

i had the same problem and applied a tiny squirt of Deoxit10 and carefully “hand-operated” the plunger - that worked and 

That issue never showed up again…but be careful not to damage any of those tiny connected wires !!

you could also try a small amount of silicon.

good luck

ALF

968driver
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968driver replied on Mon, Aug 23 2021 3:40 PM

Not exactly a reply, but I need some advise from a B&O turntable specialist.
I have restored my Beogram 8002 the best I could.
The only thing that doesn't work is the auto return function at the end of a record.
The Pause function, where the tonearm moves to and returns from its rest position to the same groove of the pause, works perfectly. This indicates that the counter of the revolutions of the drive shaft is working perfectly.
I don't understand, or am I missing something???
Any help is much appreciated.

sonavor
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sonavor replied on Mon, Aug 23 2021 6:12 PM

I have never seen a Beogram 8000 or 8002 with the problem you describe so I can't advise you on a specific answer/solution for the issue.

Unlike the Beogram 400x series turntables where there is an end stop switch and a run-out groove detection circuit, the Beogram 800x turntables rely on the two position sensor signals to count and know where the arm is. 

If you remove power from a Beogram 800x turntable when the tonearm is out over the platter area...then plug the Beogram back in, it will determine that it doesn't know where it is and automatically returns the tonearm to the home position.  The microcomputer keeps track of the start position and counts the sensor pulse to know where the arm is so the logic defaults to return the tonearm home if the microcomputer doesn't know where it is.

It is interesting that the pause mechanism works and the initial set down position works.

When you have an empty platter and press PLAY does the Beogram 8002 scan for a record and return automatically?

Or is it only the end of record play that you have the problem?
You might have to connect up probe wires to the main board and observe the sensor signals on a two (or ideally, four) channel oscilloscope.
Another thing to try would be a different PCB1/PCB2 set to see if the problem is with the circuit board or the sensors.
I realize those options are not available to a lot of people but it is a suggestion if possible to do.

Otherwise you might have to start replacing parts on a try-and-see basis.

I have had owners send me their Beogram 800x boards for testing so that is an option.  I keep fully working Beogram 8000 and 8002 workbench units handy for doing that. You would have to send me a private message via the Beoworld Forum messaging.

-sonavor

968driver
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968driver replied on Mon, Aug 23 2021 7:59 PM

Hi Sonavor, thanks for your answer.

With an empty platter the 8002 scans the platter and returns the arm to the stop position.

With a record, the platter keeps turning and the stylus stays in the last groove. When I carefully lift the arm and move it about 5 mm to the left (slightly over the record label) then auto return engages, the arm returns to the stop position and the platter stops turning.

The start position is detemined by the microswitch and is correct.

The "Pause" function returns the stylus to the previous exact location.

This is something I cannot understand for the moment.

I made all adjustments of the service manual, replaced all electrolytic capacitors and resoldered the PCB's.

Tomorrow I will connect an oscilloscope to check the optical signals of the arm position sensor.

This Beogram 8002 is in a very good optical condition and I would like to keep it as original as possible.

If no solution is to be found, I can always install an end of range switch to activate "Stop" and auto return.

Best regards, Frans.

 

 

968driver
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968driver replied on Mon, Aug 23 2021 7:59 PM

Hi Sonavor, thanks for your answer.

With an empty platter the 8002 scans the platter and returns the arm to the stop position.

With a record, the platter keeps turning and the stylus stays in the last groove. When I carefully lift the arm and move it about 5 mm to the left (slightly over the record label) then auto return engages, the arm returns to the stop position and the platter stops turning.

The start position is detemined by the microswitch and is correct.

The "Pause" function returns the stylus to the previous exact location.

This is something I cannot understand for the moment.

I made all adjustments of the service manual, replaced all electrolytic capacitors and resoldered the PCB's.

Tomorrow I will connect an oscilloscope to check the optical signals of the arm position sensor.

This Beogram 8002 is in a very good optical condition and I would like to keep it as original as possible.

If no solution is to be found, I can always install an end of range switch to activate "Stop" and auto return.

Best regards, Frans.

 

 

sonavor
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sonavor replied on Mon, Aug 23 2021 9:00 PM

That is good and interesting information.

It sounds like the position counter doesn't reach the return limit on the record you are playing.
Have you tried some different albums?  Ones with different length run-out grooves?  Maybe even test a couple of 45 RPM, 7" records.

If that doesn't reveal any valuable information I am just starting another Beogram 8002 restoration myself. I should be at the stage where I can bench test it soon.
When I get to that stage I will make a point to capture the position sensor signals during the run-out groove.  We can compare the signals.
I have never looked at the control signals during that section as it has never presented a problem.  It will be good to have that information for a correctly operating Beogram 8002.

I will let you know when I have that information.

-sonavor

968driver
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968driver replied on Tue, Aug 24 2021 9:20 AM

Hi Sonavor,

the "no auto return" problem is with all 33 rpm LP's or 45 rpm singles.

I observed the following:

The distance from the center of the turntable spindle to the last run-groove of a typical LP is 53 mm.

(auto return does not happen).

With no record on the platter, the distance from the center of the turntable spindle to the point of auto return is 76 mm.

(auto return at 76 mm from the center of the spindle).

The arm position 1 (junction of R8 and R10) and 2 (junction of R9 and R11) signals are clean square waves with an amplitude of about 3 V.

(I don't know how to insert the oscilloscope picture).

Best regards, Frans.

 

968driver
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968driver replied on Tue, Aug 24 2021 9:47 AM

Now I observed something else that I did not observe earlier.

When the tonearm reaches the run-out groove, no auto return happens, I have to push the "STOP" button to return the tonearm.

If, however, I leave the tonearm in the run-out groove, after about 42 seconds the tonearm auto returns.

Now I am really confused!

 

sonavor
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sonavor replied on Wed, Sep 15 2021 2:43 PM

I posted some oscilloscope photos of a Beogram 8002 servo motor drive signals and the two position sensor signals.  I included a measurement of the Beogram 8002 going through the run-out groove of a record.

-sonavor

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sonavor replied on Sat, Oct 9 2021 12:44 AM

968driver:

Now I observed something else that I did not observe earlier.

When the tonearm reaches the run-out groove, no auto return happens, I have to push the "STOP" button to return the tonearm.

If, however, I leave the tonearm in the run-out groove, after about 42 seconds the tonearm auto returns.

Now I am really confused!

 

Here is some additional information regarding the tonearm not properly stopping and returning during the run-out groove.

First, there could well be an electrical issue causing this type of problem.
However, it can also be a simple mechanical issue such as not having a correct or good belt on the Beogram servo motor.
On a recent Beogram 8000 (same tangential arm drive mechanism as the Beogram 8002), I did a restoration where everything appeared to work fine.
All of my tests for the completed turntable passed.  Then, while observing the record play I caught it missing the run-out groove and not stopping (and returning home).  

At first the problem was intermittent but steadily got worse. 
Since all of the voltages and sensors checked out I decided this might be a belt issue.
I changed out the old servo belt (who's source was unkown to me...it was on the turntable when I got it).  The new belt was a Beogram 8000 belt from Martin so I knew it had to be good. 

The problem immediately was gone. 

So in my case, there was a slight poor performance of the bad belt that was throwing the Beogram 8000 off. 

As I mentioned earlier, there certainly can be other types of failures that can cause this error but sometimes, as in my example case, the solution could be simple.

-sonavor

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