Nakamichi MB-75 e-disc error

frobek · 22nd December 2012, 02:08 PM

Hallo,
My Nakamichi MB-75 displays e-disc error message on the display.
I red the service manual, but there is nothing about it.
Have you any experience with it?

seankane · 23rd December 2012, 03:51 AM

The laser pick up could be dirty or out of alignment. Have to you tried cleaning it with one of those discs and solution?

frobek · 28th December 2012, 04:03 PM

I disassembled the unit and I noticed that the spindle motor doesn't work. Any suggestions?

Mooly · 28th December 2012, 04:09 PM

Car audio isn't my thing but for CD generally the focus point on the disc has to be found before the spindle motor operates. Its easier to focus on a stationery object rather than a spinning one.

Could be the laser or a problem with the focus search routine.

frobek · 28th December 2012, 04:13 PM

Maybe you are right, laser is trying to focus and isn't able to read the CD.

Mooly · 28th December 2012, 04:16 PM

Can you see the lens performing the focus search routine ? In other words moving up and and down a couple of times.

frobek · 28th December 2012, 04:42 PM

Yes, it is moving up and down.

Mooly · 28th December 2012, 05:38 PM

Next step is to confirm laser is lit. Without a power meter the best you can hope for is a "visual" check (safety warnings apply... don't stare into the beam and don't get to close and on axis to it) and a check of the current consumption of the laser diode but that gets pickup specific.

frobek · 28th December 2012, 06:03 PM

Yes, but due to the radio construction it is impossible to run it without the CD, but with CD it's hardly to see anything. Anyway I can't see laser light reflection on the CD. I measured voltage on the laser diode it's ca. 2,2V.

Mooly · 28th December 2012, 06:29 PM

The voltage on the diode won't reveal much, its the current thats the important figure. And that brings another problem because laser diodes are very static sensitive although in circuit there is less of a problem.

I understand what you say regarding accessability... I don't know what to suggest tbh. Maybe there are dedicated jigs and extension leads available but that's hardly a diy option.

It may or may not be a faulty pickup and without the detailed checks needed its not possible to say.

22nd December 2012, 02:08 PM	#1
frobek diyAudio Member Join Date: Dec 2012 Location: Poland	Nakamichi MB-75 e-disc error Hallo, My Nakamichi MB-75 displays e-disc error message on the display. I red the service manual, but there is nothing about it. Have you any experience with it?

23rd December 2012, 03:51 AM	#2
seankane diyAudio Member Join Date: May 2010 Location: Washington State	The laser pick up could be dirty or out of alignment. Have to you tried cleaning it with one of those discs and solution? __________________ Pyramid 52 Amp Power Supply----Fluke 787 Processmeter----Tektronix 465 Scope----Velleman HPS40 Scope----Soldering Iron----Desoldering Iron----Hejet HJ 500-S Heatgun----DM4070 Digital LCR Meter----Propane Torch

28th December 2012, 04:09 PM	#4
Mooly diyAudio Moderator Join Date: Sep 2007	Car audio isn't my thing but for CD generally the focus point on the disc has to be found before the spindle motor operates. Its easier to focus on a stationery object rather than a spinning one. Could be the laser or a problem with the focus search routine. __________________ ------------------------------------------------------- *A simulation free zone.* *Design it, build it, test it.*

28th December 2012, 04:16 PM	#6
Mooly diyAudio Moderator Join Date: Sep 2007	Can you see the lens performing the focus search routine ? In other words moving up and and down a couple of times. __________________ ------------------------------------------------------- *A simulation free zone.* *Design it, build it, test it.*

28th December 2012, 05:38 PM	#8
Mooly diyAudio Moderator Join Date: Sep 2007	Next step is to confirm laser is lit. Without a power meter the best you can hope for is a "visual" check (safety warnings apply... don't stare into the beam and don't get to close and on axis to it) and a check of the current consumption of the laser diode but that gets pickup specific. __________________ ------------------------------------------------------- *A simulation free zone.* *Design it, build it, test it.*


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28th December 2012, 04:03 PM	#3
frobek diyAudio Member Join Date: Dec 2012 Location: Poland	I disassembled the unit and I noticed that the spindle motor doesn't work. Any suggestions?

28th December 2012, 04:13 PM	#5
frobek diyAudio Member Join Date: Dec 2012 Location: Poland	Maybe you are right, laser is trying to focus and isn't able to read the CD.

28th December 2012, 04:42 PM	#7
frobek diyAudio Member Join Date: Dec 2012 Location: Poland	Yes, it is moving up and down.

28th December 2012, 06:03 PM	#9
frobek diyAudio Member Join Date: Dec 2012 Location: Poland	Yes, but due to the radio construction it is impossible to run it without the CD, but with CD it's hardly to see anything. Anyway I can't see laser light reflection on the CD. I measured voltage on the laser diode it's ca. 2,2V.

28th December 2012, 06:29 PM	#10
Mooly diyAudio Moderator Join Date: Sep 2007	The voltage on the diode won't reveal much, its the current thats the important figure. And that brings another problem because laser diodes are very static sensitive although in circuit there is less of a problem. I understand what you say regarding accessability... I don't know what to suggest tbh. Maybe there are dedicated jigs and extension leads available but that's hardly a diy option. It may or may not be a faulty pickup and without the detailed checks needed its not possible to say. __________________ ------------------------------------------------------- *A simulation free zone.* *Design it, build it, test it.*

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