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Beogram 8000 issues

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Keiko5
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Keiko5 posted on Sun, Apr 22 2012 10:20 PM

I received the tachodisc from Martin (Thanks!) and installed it in the Beogram 8000.  The platter turns wonderfully and at the proper speeds. The variable speed adjustments seem to work as well.  The arm moves right and left and drops and raises as it should.  That's the good news.  

It is still having issues.  It doesn't seem to recognize the beginning of a record, or if a record is on the platter.  When I press Play, the carriage moves inward, but it will continue inward until it runs out of threaded rod.  It will not drop, nor will it return to rest on its own. If I press << or >> as the arm is moving, the arm will stop, then I can press Play again and the arm will drop, and track the record properly.  However after 40 seconds the arm cues up and returns to its rest.  When I cue the arm to the end of a record and let it run out, it will not lift and return, it just sits in the leadout groove until about 40 seconds and then cues up and returns to rest.  The << and >> buttons work fine and will cue up the tonearm, and track it right and left at variable speeds depending on how hard the buttons are pushed.  If I press Stop, the arm cues up and returns to its resting spot and the motor shuts off.  The sensor arm bulb illuminates, but the red LED that indicates the arm is in motion doesn't light.  It will blink if I press Play again while the tonearm is down.  I'm not sure what the blinking LED is supposed to indicate.  With the stylus on the record, when I press Pause, the arm raises, and after about 10 seconds it parks itself.

So I don't know if the problem is with the sensor arm not recognizing a record, or if the problem is in the CPU circuit that counts the revolutions of the sprial shaft.  The fact that it doesn't recognize the end of the record seems to indicate a problem with the CPU not receiving the necessary information about carriage position from the revolution counter.  I think I am close to getting the 8000 sorted, but I can't figure out what is causing this problem.  If anyone can help me diagnose the cause of the problem, I'd appreciate it. 

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Dillen
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Dillen replied on Sun, Apr 22 2012 11:04 PM

If the capacitors are still the original, I suggest you grab a kit and replace the lot.
Aging capacitors can cause all kinds of strange issues and indeed instability like this.
In your case, I would also check the IR opto for the threaded shaft, dust off, check signals.
If the opto does not register carriage movement for a certain period of time while playing, the deck will assume
that something related to the tracking and/or the record is faulty or something is blocking the carriage
and a stop commend is issued. With no pulse counting, the deck will not know when to start looking for a record either
so it does match the symptoms, you are experincing.
(You have all connectors plugged in, right ?)
But again, what looks like a faulty opto circuit CAN be caused by bad capacitors and/or cracked solder joints elsewhere
(and there's lots of them in there) so don't focus too much on the pulse count if the opto itself seems fine.

The blinking LED at the sensor arm indicates that the repeat function has been activated.
If it does not light up normally while playing, check for bad solder joints and ... replace capacitors.

Martin

chartz
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chartz replied on Mon, Apr 23 2012 11:27 AM

Indeed. My two examples had bad solder joints which caused erratic behaviour. This is really the plague of these decks. No such problems in older B&O equipment. I didn't have any bad solders on my Beolab 5000 amplifier or Beogram 4000 turntable for instance. But loads of them inside both Beomaster 8000 and 6000!

Jacques

Keiko5
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Keiko5 replied on Mon, Apr 23 2012 3:01 PM

Yes, I already repaired 9 joints.  5 were definitely cracked and 4 were suspect.  I am in the process of ordering a cap kit from Martin.  Compared to the 4002/04, the 8000 is a PITA to work on.  It has now become a bit of a crusade to get this thing to work right.

BeoWolfGang
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I am new to the site.  Who is Martin and how do I reach him.  I need capacitors and tackodisk for a 8000.

 

Ewald.

Menahem Yachad
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This is a bad solder failure on all these TT's. It is under the keyboard, and is the control for the << and >> buttons.

Good technique is to remove this copper tab completely from the plastic mounting, then reheat a new solder blob onto the oxidized copper, THEN ONLY replace it onto the plastic mounting, and quickly resolder the black wire.

Menahem


Pellocas
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martin olsen, is our saint for parts for our beograms, besides many doubts to repair them
Pellocas
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martin olsen, is our saint for parts for our beograms, besides many doubts to repair them
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