Accuphase DP-80 CD Not Reading - diyAudio
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Old 15th January 2014, 06:40 AM   #1
flyong is offline flyong  Singapore
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Join Date: Mar 2009
Default Accuphase DP-80 CD Not Reading

Hi,

Is anyone can help me to solve my Accuphase DP-80 transport problem which currently is unable to read any CD?

The transport was working fine in one of the day when I tried the new 75 ohm digital link cable to my DAC. Previously I was using the TOSlink cable and think of changing it to 75 ohm cable.

Hooked up both cables to my DAC and did an input selection on DAC, started to play a song from my transport. Everything sounds good from both TOSlink and 75 ohm cable.

Problem happened when I changed the CD, after loaded the second CD in the transport and started to play it. It no longer read the CD anymore and no track number was displayed on the front panel. After few seconds, the tray opened by itself and tried a few CDs but with the same result.

First thing come in my mind was the laser pick-up failure (Sony BU-1C) but sad to accept this because the pick-up was replaced less than a year.

I have a spare laser pick-up bought from eBay same as the first one and happy to replace it onto the transport. Shocked to me when the transport was still unable to read any CD and the tray opened after few seconds. The disc motor run for few seconds but stopped before CD was ejected.

Sad to see this result because both laser pick-ups were claimed to be new and bought from the same seller from eBbay.

Is anyone has the Accuphase DP-80 service manual? Hope to get some idea what is going to the transport from the manual or any idea what happened to the transport?

Sorry for the lengthy grandmother story here and thanks for reading.

Regards,
flyong
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Old 16th January 2014, 03:30 AM   #2
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In my experience, which goes back to the dawn of cd, BU-1C laser/mech units NEVER fail. They only ever need proper adjustment and *proper* lubrication. From the sound of it, assuming the laser/mech replacement was done competently, yours most likely has a lubrication issue. To diagnose, simply turn off power, then, onto a padded surface, tilt the unit forward until it is fully or almost sitting on it's face, then return it to normal orientation. Now try playing a disc. If the disc starts up fine, then you pretty darn definitely just need proper lubrication on the laser's tracking sled guide rails. The tracking sled is a "linear motor", essentially a precisely positionable solenoid, which is infinitely durable & reliable, with the only maintenance/critical issue being the guide rail grease. You CAN'T USE JUST ANY GREASE! You need a very specific sort of lub that is halfway between a grease and an oil, slick enough to give no resistance to movement, but viscous enough to maintain a slick film between two pieces of scraping metal. A "new" BU-1C will have been sitting on a shelf for at least 20 years, so that lub absolutely can NOT be relied upon, so no surprise if it's the problem. Your challenge will be to find the right oil-grease.
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Old 16th January 2014, 11:05 AM   #3
flyong is offline flyong  Singapore
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Join Date: Mar 2009
Hi,

Thank you for the reply and suggestion. Tried your method to tilt the player but no avail, it still can't read the CD. The lens can easily glide on the guide rail because it is supported by the magnet and solenoid. Will buy the lubricant to grease the guide rail.

Cheer
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Old 17th January 2014, 01:16 AM   #4
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Next step is to observe, internally, what happens when you operate the mech. Power up, then open the tray. Manually move the laser sled out back from the center an inch or so. Tell the tray to close, with no disc, and you should see the sled move right back to center position, then the laser should light(turn off room lights & you should easily see red glow in lens, without looking straight in) and lens should move up & down 2-3 times. If this is what happens, now load a disc. Does disc spin?
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Old 17th January 2014, 02:24 PM   #5
flyong is offline flyong  Singapore
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Hi Stephensank,

First for the laser sled, it does move back to center position after the tray closed.

For the laser light, it is hard to see through naked eye but I used digital camera to focus on the lens, I can see the red glow in the lens after the tray closed. However, both old and new laser pick-up I can see the laser light....

Something can't explain, the old mech motor was able to spin after loading the disc but last for few seconds only, after that the tray ejected the disc. For the new laser pick-up mech, the motor doesn't spin at all, I remembered when the first time I changed the pick-up, the motor did spin as the old mech and couldn't read the disc before ejected the disc.

I am thinking to switch the motor from old pick-up to the new one, but it seems like not easy to remove.

The laser is able to light up, is it meant that the diode is good? I have no idea what to do now.

Thank you for all the suggestions.
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Old 18th January 2014, 07:36 PM   #6
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Location: Germany
If the tray opens by itself, then there usually is something amiss with tray close detection (bad switch contact etc.). These units also use a belt in the tray mechanism though, which may be worn and giving problems, i.e. by proper end position not being reached. Try loading a CD with the unit on its side (tilted as far as needed to keep the CD from falling down).

In new pickups there often is a solder bridge across the laser diode that is supposed to prevent ESD damage while the cable is not yet attached. Check that, too.

Last edited by sgrossklass; 18th January 2014 at 07:38 PM.
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Old 18th January 2014, 09:51 PM   #7
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From here, it gets difficult to help by "remote control". While we are sure your laser diode works, we can't be sure that it is outputting adequate light, without an optical laser power meter, e.g., Leader LPM8000(not very expensive to buy used). The output spec for that laser is 0.24mW, in case you do get an LPM. It will fail to maintain focus if it is lower than about 0.20mW.
Referencing the last poster, it is normal for this unit to "spit out the disc" if it can "see" that a disc has been loaded, i.e., not an empty tray, but fails to read properly.
All we are sure of as yet is that a)laser is lighting, and b)sled is lub'd well enough to allow closure of the inside limit switch, allowing laser lighting & focus search. We don't know yet if focus lock is achieved, thus don't know yet if platter motor is failing to spin up because focus is not achieved or if there is a platter motor drive problem. The way to *mostly* tell if focus has locked but platter motor/motor-drive-circuit is the problem is to gently manually spin the cd(clockwise) just after loading and listen for a "squealing" sound from the laser's tracking coils. If you hear the squeal, then focus has locked and there is a problem with the motor drive circuits(these never have actual motor faults that I have ever seen, at least).
And, btw, you would not see laser lighting if the static protection shorting jumper was still in place.
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Old 20th January 2014, 05:14 AM   #8
flyong is offline flyong  Singapore
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Join Date: Mar 2009
Hi,

Thank you for all the reply and suggestion.

I guess even the new laser pick-up that I have changed, it has something not right. This is because the motor did not spin the disc and I manually turned it to make the motor spin but nothing responded from the lens.

Without disc, I can see the new lens seems like focus (the sled moves and lens up and down) for a while but after that, the sled moves further away from the motor up to the end of the guide rail. What the weird response of the new laser pick-up!!


I believe the CD player had gone beyond someway that I can get it back to work, the hope is slim and may need the professional technician help on this.

Thank you for all the responses from the forum and at least I learnt something there.
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Old 21st January 2014, 01:51 AM   #9
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Well, if you don't have anyone there in Singapore you know you can trust with this lovely machine, I would be happy to get it back up & running for you. Shipping costs will be quite substantial, but I have 100% confidence I would be able to have it back in perfect working order for 250usd or less.
You can find my info at stephensank.com.
It's really too darn nice to simply give up on.
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Old 22nd January 2014, 01:21 PM   #10
flyong is offline flyong  Singapore
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Join Date: Mar 2009
Hi stephensank,

Thank you for the offer and let's me explore the possible way to service locally.

The player is super heavy (~15kg), shipping the whole unit to US is very costly unless if I just ship some parts..

Cheer,
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