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Denon DP-47F tonearm issue.

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Denon DP-47F tonearm issue.

Postby lucius72 » 27 Mar 2018 01:29

I have the Denon DP-47F that it's an Ebay purchase and I have a few problems with the tonearm.First the tonearm wouldn't move but I've managed to fix this problem by spraying a solvent in the tonearm bearing as it seemed stuck. The only issue I have now is that the tonearm just drops on the vinyl after 5-6 seconds instead of slowly lowering the needle on the record. The same thing happens when the tonearm raises.Have anyone encountered this before and what can be the cause of it? Thanks.
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Re: Denon DP-47F tonearm issue.

Postby quixcanardnon » 06 Jun 2018 16:19

I have one of these models with the same problem. Anyone else ever seen/diagnosed this? Can't find another thread with this issue.

I have balanced the arm with the counterweight, then set tracking correctly, and when the stylus is in down position, its tracking force does measure correct. But it won't lower slowly, it just hovers for several seconds then just dives onto the record surface.

I have the service manual and none of the listed adjustments cover this so it suggests to me that some weight or spring screw is just wiggled wrong somewhere.
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Re: Denon DP-47F tonearm issue.

Postby quixcanardnon » 10 Jun 2018 02:49

Having done more experimentation with the counterweight and the spring screw on the tonearm, it appears that this issue is really a problem with the vertical lifter servo/motor/mechanism/circuit. Essentially everything works except the tonearm won't raise or lower gently, it only jumps up or down. So whatever mechanism is supposed to provide the gentle damping ain't working.

Anyone have insight on how to investigate further? Thanks!
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Re: Denon DP-47F tonearm issue.

Postby captmark » 11 Jun 2018 09:13

Do you want the bad news or the bad news? You "might" get lucky and have a loose or broken wire on the servo circuit between the main PCB and the arm PCB. If so, play the lotto-it's RARELY that easy...the problem is usually much deeper into the beast.

Your problem(s) are most likely what is shown in the attached pictures. There are two coils in a housing that control vertical motion of the arm, one for the lifter and the other for the servo control that also handles the VTF. The image (IMG0694) not installed in the arm shows a healthy set up with all four wires attached to the corresponding wires you see coming out of the bottom of the arm and attaching to the small PCB board that also houses the CDS Sensors. IMG0695 (in the arm) is what you most likely have going on-one of those wires has broken off the connection.

It is accessible without pulling the whole arm out, but small consolation. It is a PITD - bearings and wires and plates oh my have to come loose. The wire is incredibly fragile and obviously brittle to have broken. You'll need the luck of the Irish if there's enough wire left and the patience of Job to try to reconnect it.

It is "easier" to swap the whole assembly for another; DP35-47 and I think even 61/65's have the same internal coil set up, but if you prefer to swap the whole arm (EASIER!)only the 47F arm works with the 47, mostly because of the shared VTF/Anti-skate/servo wired on one knob verses two knob set ups, but either way you're talking donor table and doing this twice. I wish you the best of luck.
Attachments
IMG_0695.JPG
IMG_0694.JPG
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