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Old 03-18-2023, 08:44 AM   #1
PowerAmpFreak
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Default Denon DN-501C CD-player not reading CD

Hello, I have tried to see what could be the problem in this CD-player with no luck.
The service manual for Denon pro gear is hard to come by.
The player loads the CD, spin the disc, but instead of focus adjustment the sled itself is jumping a few millimeters, and tries about 5-6 times and shows "Media Error"
The CD-transport itself has a partnumber of TD-S208PR-6, not much of info able to find.
This can be a problem with the PCB itself, but most often the transport is the problem.
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Old 03-18-2023, 02:40 PM   #2
redwire
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Default Re: Denon DN-501C CD-player not reading CD

The sled should move smoothly.
Commonly I find the transports need lubrication on the rails and worm-shaft. With oil and grease, they get too stiff and can jam/stick gears slip.
I use light grease on the rails and light oil the worm-shaft only if that matches the factory lube (oil vs. grease) there. It's a grease vs oil question. Clean off the old lube with IPA and Q-tips.
I would also check the sled home sensor switch is working, that the sled is not too far off in position.
I thought first step is to spin up the disc, then focus step and look for pulses from the CD pits. If it does not see anything, it must be moving the sled hunting.
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Old 03-19-2023, 08:02 AM   #3
PowerAmpFreak
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Default Re: Denon DN-501C CD-player not reading CD

Thanks
I cleaned the sled with isopropanol there are no difference
The homeposition switch is measured ok

Here is a youtube vid of the problem:
https://youtu.be/HuLwPi6dgaE
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Old 03-19-2023, 11:10 AM   #4
R_J
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Default Re: Denon DN-501C CD-player not reading CD

It is very likely the laser pickup has failed.
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Old 03-19-2023, 11:37 AM   #5
PowerAmpFreak
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Default Re: Denon DN-501C CD-player not reading CD

Please tell how you came to that conclusion.
Cause the focus error is so big and pull the sled? Due to no signal from pickup?
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Old 03-19-2023, 12:47 PM   #6
lotas
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Default Re: Denon DN-501C CD-player not reading CD

Check all microswitches (for a short circuit), these may be somewhere else.
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Old 03-19-2023, 01:03 PM   #7
redwire
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Default Re: Denon DN-501C CD-player not reading CD

If the transport is hunting to see a CD, it can be a mechanical problem (sled too far in) and this has a belt drive for the worm shaft?
Or an electronic problem, you should find the factory testpoint for the pickup photo detector signal and use an oscilloscope to see if pulses are there. This would indicate the laser and focus servo are OK, data coming in but not the lead in. I think this player has a lot of circuitry in the transport.

The service manual might be here https://****************/load/audio/denon/279-4-2 but I don't have membership on the russian site. The URL gets blocked out here. Trying again: //remont-aud dot net/ is the * portion.

The middle main board says DN700C so the 501 may also be similar.
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Old 03-19-2023, 01:24 PM   #8
lotas
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Default Re: Denon DN-501C CD-player not reading CD

ser. manual
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Old 03-19-2023, 02:17 PM   #9
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Default Re: Denon DN-501C CD-player not reading CD

Thanks a lot. The service manual will help a lot. Thanks
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