Hi Chrisbou, Welcome to BeoWorld

Would you please clarify the symptoms because I’m not sure whether I understand them correctly.

If you press PLAY, does the arm not move at all

If you press <<, presumably you can move the arm to the desired spot on the disc, so the left and right manual movement controls work OK.  This means that the belt and motor are OK.

If you then press PLAY when the arm is in the right position above the disc, the arm does not lower or move at all.

For the third point above, do you hear a click at all when you hit the PLAY button.  Already starting to sound like a faulty coil or sticky mechanism but I'm not 100% sure.  Has this unit been operating regularly or has it been standing for a long time?

Thanks

Geoff

Thanks for replying Geoff! when I press PLAY ,the arm does move close to the edge of the record but stop short of reaching it.Then,I press forward and the arm will go over the record but the play button won't make the arm drop.I have check all of the detectors and motors and everything should work.the arm detector sends the signal correctly to the processor,when I put some voltage to the lift coil 'the arm will drop.Another thing,I can change the speed manually but it wont change when the detector arm goes over the ribs of the turntable.I'm really scratching my head!!!           When I press PLAY,no click is heard and,finally,yes it has been standing for a long time but the reason it is so is because it was making that problem.  thanks   Chris

Hi Chris

Thanks for the updated description of your problems, it gives me a better idea of what is going on.  I have done a lot of work on my BG6006 and managed to get it working properly but there are plenty of things that I still have to learn about this machine.

The first point that you have made is that when you press PLAY, the arm comes up short of the turntable.  You don’t say by how much, is it a few mm or cm?  If it is only a small distance, this is corrected by adjusting the position of the limit switch.  The manual states that the limit switch is set up by putting on a 30cm disc, determining the error in the drop position and then adjusting the position of the limit by loosening the screw and moving it to compensate.  Perhaps you could try that and at least you will have the correct starting position to work from.  Thereafter, we will have to decide what is stopping the arm from finding the right position and dropping.

I had some problems with the lowering mechanism recently and I tested it by giving the coil a 5v supply.  In my case, the plunger was stuck and simply wasn’t moving.  After a bit of pulling, pushing and cleaning, everything worked as it should.  It sounds as if you have also done the 5v test and your coil and lowering system is working OK. 

You also mentioned that you don’t hear the relay click and it is now starting to sound like the detection system is holding everything out.  The fact that the system is not picking up a record size change and altering the speed accordingly also seems to be pointing in this direction as well.  The disc detection logic terminates at P6.9 which is Pin 33 on the micro.

Yet you say that the detector system is working so I presume that you measured the voltages at that point.  After you reset the limit and get the arm to move to the correct starting position, do some more checks to see how the voltage changes at Pin 33.

I must admit that I am starting to get confused myself.  If the detector is happy and the arm is in the right position and the drop mechanics are working and you get 5v at the coil ….. everything should be OK.  I’ll have to think about what else could possibly be causing your problem.  Next time I open up my unit, I’ll check to see what is happening in the detector circuit during these different situations and try to verify the logic.

Hope that this has helped a bit

Geoff

Tonearm stops just short of the record = clean and lubricate the threaded shaft and replace the servo motor belt.

It's a matter of friction as the tonearms are slowed down to get to the exact starting point and this is where the mechanics will have to work precisely and without slippage. The arm won't lower until the correct number of pulses from the opto sensor has been counted.

Martin

Hi Martin

I had wondered about the belt slipping option but this did not appear to be an issue because the arm can be moved to any position using the manual button.  If you get a small amount of slipping, what stops the motor doing a few extra revs to compensate?  Does the motor continue driving until the opto sensor reaches the correct amount of revs or does it time out?  I would be interested to understand what condition causes this process to stop.

Thanks for your help

Geoff

Thanks to both of you guys!

I just cleaned the threaded rod and lubricated everything but the problem persists.The belt,althought not the triangular type seems to be fine as there  is no slippage at all and no dragging.Could it be the problem anyway?Since we last corresponded I changed the 0ic1 5 volt regulator cause it was giving 4.8 volt so I thought maybe it had something to do with it but no.

yes Geoff,I did check ai pin p6.9 and then decided to check at  pin 33 of the IC itself and  it's ok.

I also checked every detector to see if they were giving the right signal and...everyone do(or does?)

For the question you asked Geoff,when I press PLAY,the arm moves about 3 cm then stops.If i bring the arm with the forward button to about halfway to the record and then unplug the turntable,when I plug it back,the arm will return toward the right again for only 3 cm.If I want to go all the way,I have to use the return arrow.

If I press the TURN button,(at the stop position),the motor will turn to the speed I want and if I press STOP,it will stop.However,if I press PLAY and then press STOP then it won't react at all.now the funny thing about this whole thing is that I have TWO such machine with exactly the same problem and yes,Idid turn of my benchlamp before trying anything else.

I'M REALLY PUZZLED!!!

thanks again for all your help.I appreciate it.

Chris.

I can't believe that you have two machines which are both playing up to that extent!!  Are you sure that the voltage supply to your house is not rediculously low for some funny reason.

I have checked the stroke and the speed of the arm during the initial movement and come up with the following information which is the same on both my BG6006 and BG8002.  The travel distance is 46mm and it completes this in ±2.0 secs.  I would be interested to know if your initial travel is being limited to 30mm and how long is it taking to do this.  If your short distance is also taking around 2 seconds then I would have to agree that slipping and sticking are likely issues.  If the speed is correct and it is covering the 30mm in 1 to 1.5 secs, then the arm appears to be coming up against a stop somewhere.  Maybe the motor is not performing properly and running slow???  --but two of them at the same time???

The plot thickens!!

Geoff

When the tonearm halts, try removing the belt without disturbing the position of the opto interrupter and watch the motor. If it rotates, the tonearm carriage doesn't move freely enough. Clean the threaded shaft and the nylon bushing under the carriage. Add a little fresh silicone grease and it'll be fine.

These Beograms count pulses, it's not timed. If the correct number of pulses can't be reached, it won't lower. 

Martin

I have a Beogram 4002 type 5511 and encounter some problems maybe you guys here can help/advise me.

 1) after the arm drop down to play LP, it will just static, so the music is keep repeating at the same position.

2) left channel no sound or extremely low volume

Any advice on this? 

The motor (for the arm) can move by pressing >> or <<