Denon DP80 & DP75 Owner's Thread

Zarathustra said:
Just bought a Denon DP-80 in pristine condition inside and outside with an ugly DK-200 console which is ment for the DP-6000 & 7000 I believe.
If everything works perfectly, which it does, should I perform a recap anyway, some transistors (no idea yet which one for now) and the VR's?
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If were me, only a recap if all else is working well. Spritz of Deoxit for the controls. Plus, of course, a thorough cleaning & new lube (new sponge to hold the oil, new isolation between the platter halves, etc.).
The 'Vinyl Engine' has the manuals for download and the templates if you are making a plinth.
 
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MX117.MC7150 said:
If were me, only a recap if all else is working well. Spritz of Deoxit for the controls. Plus, of course, a thorough cleaning & new lube (new sponge to hold the oil, new isolation between the platter halves, etc.).
The 'Vinyl Engine' has the manuals for download and the templates if you are making a plinth.
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Thanks for the advise.
 
MX117.MC7150 said:
If were me, only a recap if all else is working well. Spritz of Deoxit for the controls. Plus, of course, a thorough cleaning & new lube (new sponge to hold the oil, new isolation between the platter halves, etc.).
The 'Vinyl Engine' has the manuals for download and the templates if you are making a plinth.
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How is your Denon working Glenn? We're having a GTG on Feb 1st at my house.
 
Aerobat said:
How is your Denon working Glenn? We're having a GTG on Feb 1st at my house.
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Still singing sweetly.
Was hoping to make it to Keith's this weekend, but, unfortunately, I'm going to miss that. But, Your Feb gig sounds very doable. Look forward to it. Thanks.
 
I wanted to say a thank you to everyone on this thread and elsewhere on this forum for the amazing wealth of knowledge on Denon DP80/75 and generally all things related to vinyl playback. It took a bit of time and effort for me to reach here but I think it was worth it.

Denon DP-80 (Motor fully serviced)
Denon DK-300
Technics EPA-250 (Bearing upgrade and knife-edge enhanced by JP Jones)
Denon DL-103D (Boron cantilever and line-contact stylus and wooden body by VAS)
MNPCTech Isolation footers

DP80.jpg
 
Hi Denon fans, looking for a little help with a DP-75 I am rebuilding.

I have replaced the electorlytic caps, and some transistors on the KU-351 board. Everything is working, speed comes up and locks in, but there is a low level hum after it locks. I have adjusted the VR1/2 pots with oscilloscope and by hand and I cannot eliminate the hum. It is not mechanical -- goes away completely if power is cut and platter is still spinning.

There is a brief moment of silence right when the speed locks on, but then the hum resumes and is constant (slight pulsing) - like it is having trouble staying exactly locked on. Strobe is steady though. This happens at both 33 and 45. I have compared to another unit and it should be almost complete silent.

Any suggestions for what components might be causing this appreciated, thanks for any help--
 
MX117.MC7150 said:
Is the hum thru a set of speakers or directly from the DP-75?
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its from the motor as far as I can tell. not in the speakers, aside from the fact that the cartridge/arm are picking it up a little. if i listen with my stethoscope, I can hear a brief moment where the speed locks in and the humming is totally absent, but then it starts again even though the speed is not apparently drifting.
 
i do have a ground wire, that has always kind of confused me because it is not from the tonearm wiring. I tried grounding to the outlet this is connected to but no effect.
 
clintalloy said:
its from the motor as far as I can tell. not in the speakers, aside from the fact that the cartridge/arm are picking it up a little. if i listen with my stethoscope, I can hear a brief moment where the speed locks in and the humming is totally absent, but then it starts again even though the speed is not apparently drifting.
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As part of your refurb did you pull the motor out and clean the old oil out and the thrust plate and a new oil felt, etc.?
 
MX117.MC7150 said:
As part of your refurb did you pull the motor out and clean the old oil out and the thrust plate and a new oil felt, etc.?
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I did do that -- aside from the felt as I didn't have a suitable replacement. I added a little bit of oil. ball bearing and plate in good shape, maybe a tiny mark on the plate but it is not responsible for the noise.

in regards ot the motor though, do you know where to get the oil felts or is it ok to just add oil? thanks--
 
Member 'aerobat' sourced the felt for mine. He will eventually reply.

If the electronics are 'singing', then something is oscillating in the audible freq range. You mention you have an o'scope. You should be able to use it to trace the noise.
 
clintalloy said:
i do have a ground wire, that has always kind of confused me because it is not from the tonearm wiring. I tried grounding to the outlet this is connected to but no effect.
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The ground wire is meant to connect with mains ground. I connected the ground wire to the ground plug of a 3 plug receptable and then plugged this into my power strip.
 
If the ground wire is from the motor chassis, it is meant to attach to the same ground point as your tonearm ground. Having the arm and motor/platter at the same ground potential gives you the lowest noise. Grounding to PE can work, and sometimes nearly as well.
 
JP said:
If the ground wire is from the motor chassis, it is meant to attach to the same ground point as your tonearm ground. Having the arm and motor/platter at the same ground potential gives you the lowest noise. Grounding to PE can work, and sometimes nearly as well.
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My original intent. But at least on my DP80 on approaching the grounding post on my amp an electrical discharge (aka spark) would jump from the wire to the ground post when it got close. Alternately attaching it as described eliminated all noise and no sparking.
 
MX117.MC7150 said:
Member 'aerobat' sourced the felt for mine. He will eventually reply.

If the electronics are 'singing', then something is oscillating in the audible freq range. You mention you have an o'scope. You should be able to use it to trace the noise.
Click to expand...
I bought a bag of these felt rings but I can't locate it. I just used one for Glenn's TT and the rest went somewhere. You should be able to find them.

Fun fact, the one in my 1950 Webster changer is original but the one in the Denon was a plastic mesh that turned to dust.
 
Aerobat said:
I bought a bag of these felt rings but I can't locate it. I just used one for Glenn's TT and the rest went somewhere. You should be able to find them.

Fun fact, the one in my 1950 Webster changer is original but the one in the Denon was a plastic mesh that turned to dust.
Click to expand...

ah, like a felt gasket/oil seal ring, right? guess i just gotta measure it
 
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