ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Hi everyone,
After some assistance or ideas from the forum. I have a Beogram 4002 type 5521 (DC motor version) which I recently acquired and have been working through a few issues and trying to tidy up. It has recently developed an intermittent problem where it wont attempt to raise the tone arm at the end of a record before beginning to return the arm carriage to its resting position. This results in the arm being dragged for about 1-2cm before it raises and returns to home as normal. This happens perhaps every 6th LP I play, it usually seems to happen after an entire side has been played and is not easy to replicate by manually activating the solenoid with the ^ or Stop button.
When working correctly, I hear the solenoid fire at the same time the motor begins driving the worm drive to take the carriage home. When it plays up, the solenoid seems to fire a second or so after the worm drive begins returning the stylus to home causing the arm not to rise.
I have been reading through the forums thoroughly trying to figure out what this could be. I know the design of my unit is much simpler than many of those discussed on the forums such as the earlier AC motor units.
I have done a reasonable amount of work on the unit already including many new caps (replaced all the red caps), new main power cap, clean speed change relay, replace speed change pots.
Reading all the forum posts I disassembled the arm pivot assembly and cleaned and relube of the pivot points for the arm raise/lower assembly, cleaned and lightly oil the damper (it was clean but not lubricated), clean the carriage worm drive and arm pivot point. I have used ISP to clean all appropriate parts and sewing machine oil to lubricate as per the service manual (except the worm drive where i used a mix of turntable bearing oil and a light bearing grease as per the manual). There is no residual dried grease on any of the arm pivot points under decks, all is clean - the unit was supposedly serviced when I purchased it. When I manually activate any of the mechanical assembly it moves easily, the solenoid plunger moves freely, I did not lubricate this part as it didn't seem necessary. The solenoid shows no signs of damage.
The solenoid when manually activated using the keyboard is strong and reacts instantly. The arm raises almost instantly and very sharply. On play the time to drop the arm is 0.8 - 1 second and the stylus is into the grooves before the muting relay disengages so no apparent issues with the damper 'over damping' or any of the mechanicals. I have had no issues with the not arm dropping as per some other members posts.
Can anyone give me some ideas where to start looking here, I am a bit confused. My understanding of situations where solenoid drive transistors were at fault seemed to indicate this usually prevents the arm dropping, not raising and that raising is usually a mechanical issue (which I have already covered off pretty well).
Any advice welcome!
Thanks
Andrew
Hi everyone, bit of a follow up.
At this point it seems the trouble was the tonearm wiring and detector arm wiring which runs beside the solenoid and around the top of the solenoid mechanism. It appears it wasn't positioned properly from the factory, when the arm is raised the wires are pushed down, however ater playing a side of an LP the wires would work their way into the path of the mechanism and intermittently block the travel of the solenoid mechanism when trying to raise the arm.
I got to this point after replacing TIP 125, solenoid drive transistors and basically every cap in the circuit without success - sometimes the most basic issues is not the most obvious.
Hope this helps someone in the future.
Thank you for the feedback - you clearly had everyone stumped!!
Peter