laser settings for cdm4/19 cd players? (rotel RCD-855)

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Steavis

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Joined 2011
#1
I've bought a Rotel RCD-855 that I want to do some mods on. From the moment I got this player it randomly cuts out the volume for a second or 2 while playing CD's. Sometimes it completely stops playing the CD. I have already replaced all capacitors, which strangely enough made the issue worse.

It sounds to me like the focus / tracking should be readjusted, but the Rotel RCD-855 service manuals that I found online don't have any info on this, or are practically unreadable. Can I take the settings from any other CDM4/19 cd player and apply it to this player, or are settings player specific?

Thx,
Steven
 
#2
Can I take the settings from any other CDM4/19 cd player and apply it to this player
Click to expand...

No.

or are settings player specific?
Click to expand...

Yes.

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If the settings were not player specific then there would be no need for service adjustments.

If replacing parts has changed the fault symptom then that throws everything in the air. Was an original part faulty and the new part has altered things (but still with an underlying fault) ? or, has something gone amiss with the replacement procedure, and incorrect value fitted, or incorrect polarity in replacing a cap has occurred somewhere ?

Unfortunately and without detailed tests its impossible to say what might be occurring. You need to look at the recovered RF signal from the pickup RF amplifier as a first step and see whether its clean and of the correct amplitude and also that it is free from jitter and 'bounce'.
 
#3
Mooly said:
You need to look at the recovered RF signal from the pickup RF amplifier as a first step and see whether its clean and of the correct amplitude and also that it is free from jitter and 'bounce'.
Click to expand...

That is exactly the info I would find in the service manual..but that info is lacking in the ones I found online. Any idea how to check this without the service manual?
 
#4
You would have to scope around the RF signal stages. The manual I saw is very poor as well but it looks as though it is pin 24 (is it, or is it 26) of U101
 

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#7
I'm not so sure I would condemn the laser yet.

Did you replace all the electrolytics under the laser (on the servo board) ? In post #1 you mention the problem seemed worse after recapping. It might be worth checking your work/values/polarity of the replacements.
 
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