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Denon dp-51f speed problems

Posted: 24 Jul 2019 15:15
by franco77
Hello everyone, I am Italian so I hope to be able to express myself in an understandable way and I apologize if my English will not be perfect. I have a denon dp51f that suddenly started to slow down until it stopped in a few moments, I proceeded to clean the magnetic head under the plate and lubricate the moving parts without solving.
I deal with electronic repairs, but unfortunately I have no experience with these devices. I downloaded the service manual from the site. Can anybody help me with what to check?

The problem is random, sometimes I can listen to entire discs without it appearing. When it slows down, Denon flashes

Re: Denon dp-51f speed problems

Posted: 24 Jul 2019 17:36
by lenjack
This unit's speed is electronically controlled. There are no speed adjustments, and repair will be difficult, as it will probably be hard to find someone who knows how to do the repair. This turntable dates back to the early 1980's. If you do find someone, I think it will be expensive. There are a few other folks here who might have some more knowledge on this, so just wait for more responses.

Your English is very good.

Re: Denon dp-51f speed problems

Posted: 25 Jul 2019 14:59
by franco77
thank you! I await some other technical opinion

Re: Denon dp-51f speed problems

Posted: 25 Jul 2019 17:49
by Legrace
Common problem with vintage DD. I own 3, all are having speed regulation issues at some point. But I am happy to recover all 3. Two are serviced by hired technician, but the 3rd (Sony) I decide to do myself as it is lower end model so I think if I have bad result it is minor loss. Speed on this one is constantly going up and down. I refer to service manual for values of all electrolytic capacitors. I replace these across the board with new ones. I also spray clean speed adjustment pots and contacts on 33/45 speed selector switch. Afterwards strobe is holding perfectly steady. I now use this one for older records. Note the Dual and Denon the technicians also replace all electrolytic caps and they are both working properly again as well.

Re: Denon dp-51f speed problems

Posted: 25 Jul 2019 20:16
by franco77
I will try to replace the electrolytic capacitors and let you know.

Thank you

Re: Denon dp-51f speed problems

Posted: 25 Jul 2019 20:51
by Legrace
Additional steps may be necessary, but new caps always seem to be part of the solution. Good luck.