Focus on Marantz cd74 with CDM1 - diyAudio
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Old 8th November 2005, 10:31 AM   #1
drews is offline drews  Italy
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Join Date: Jan 2005
Location: Roma
Default Focus on Marantz cd74 with CDM1

Hi,
I have an old Marantz cd74 with CDM1.
Does anybody know how to set the correct parameter for CDM1 llaser (focus,adjust ecc ecc)?

Thanks
Andrea
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Old 8th November 2005, 04:15 PM   #2
drews is offline drews  Italy
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Join Date: Jan 2005
Location: Roma
I only know that for adjust the laser output, I must connect DC voltmeter between the emitter of Q239 and the ground of chassis and adjust the potenziometer so the DC voltmeter reads 500mv +- 30mV.
In the pcb of CDM1 there are 3 potenziometer, one for laser out put, one for focus error adj and the other one for Focus offset adj.
Somebody know how check focus error value and focus offset?

Many thanks

Andrea
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Old 8th November 2005, 09:40 PM   #3
guytou is offline guytou  France
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Join Date: Mar 2005
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Hi , the best would to have the CDM-1 service manual ,I have seen a link about a danish site ,I think , but sorry i dont remember .maybe try a search with "philips"?
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Old 11th November 2005, 01:07 PM   #4
drews is offline drews  Italy
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Join Date: Jan 2005
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When I close the door with a CD I can see from an angle that there is laser light. I can also see the laser flexing as is trying to focus. The motor however doesn't spin at all. Why?

The motor start only if i insert "Eric Clapton" cd, with other cd it doesn't start. If I wait one hour, so when the cd-player is warm, the motor start.
How is possible?

I have noticed that, if I tilt the cd while the laser is trying to focus, the motor start normally also if the CD-player is cold.

Thanks
Andrea
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Old 11th November 2005, 10:25 PM   #5
guytou is offline guytou  France
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Join Date: Mar 2005
Location: marseille
could be a lot of things . have a look here :

http://repairfaq.ece.drexel.edu/sam/cdfaq.htm

good luck .
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Old 14th November 2005, 09:35 PM   #6
drews is offline drews  Italy
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Join Date: Jan 2005
Location: Roma
I solv the problem

At the bottom of the turntable motor there is a screw.
The value was so high(300mV) and the normal value shuld be 0 mV

Also the laser output was so high (650mV) and the normal value shuld be 500mV
Now the CDM1 play very good, like new

Thanks to ALL

Andrea
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Old 15th November 2005, 09:55 AM   #7
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Join Date: Nov 2004
Location: Kaunas,LT
Hi,
& own this Marantz too and preparing to tweak it.Have somebody a schematics or service manual ?
Thanks
Darius
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