CDM-1 based Philips CD-304 / Marantz CD 84 Suddenly Fails to Read Disc

Salar

Member
Well, this sounds like one of those many threads about laser failure and dirty lenses.
It is not.
A Philips CD 304MKII of mine was cleaned and aligned by myself at the end of March.
All ground connections were resoldered, bearings lubricated, laser cleaned and I even
aligned the swing arm.
(BTW I think the CD-304 is almost identical to the Marantz CD-84)
But after 10 weeks of listening, over the course over three days, the Philips failed to read CDs.
First, scratched CDs startet to fail.Now it would even not read a CD with tighter tolerances, specially made for alignment, Sony YEDS-18. I used this CD for alignment in March.
.
Very strange, because the eyepatterns amplitude is still up to the norm. (But much more blurry now)
This Player uses as CDM-1 swing arm transport.

Very important:
I swapped the CDM-1 to a second one (from a Philips CD-104),
including the circuit boards for discmotor and rf-amp, but the problem persists!


Thus I am sure the failure is not transport-related, but there is something
malfunctioning on the main servo-board.

To dig in very deep:
A fine tracking signal for the radial servo seems to miss or is distorted.
But:
This is more or less a guess becausethe reading-failure starts that early, that there is hardly no time to
monitor the fine tracking signal.
It can be measured @ point 30, pin2 of IC6218 on the main servo board.
In the service manual, this signal is not mentioned, a participant in a forum pointed this out to me.
Look at this post @DiyAudio:
http://www.diyaudio.com/forums/digi...-cdm-1-swing-arm-alignment-6.html#post5093670

Maybe there is a Philips afficionado @aidiokarma and the symptom described rings a bell...?
All the best,
Salar
 
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Found the error:
One of the capacitors on the servo board, 2215 (2µ2) or 2217 (1µ5) were defective or making a short to ground.
After replacement, the CD 304 MKII is running fine now!
All the best,
Salar
 
Thanks! It took me more than a month while trying everything:
Changing all Electrolytics, changing transistors and all IC´s still available, resoldering everything, checking every cable,
even buying some Philips cheapo players off ebay using the same chipsets as the CD 304 MKII.
I am not so shure whether there was a short circuit, but the mentioned "dry" electrolytics (not tantal, but using aluminium with a dry electrolyte) showed some green rust on the legs.
I did clean the boards half a year ago with water and seal the copper plane with wood oil a week
later (The first paints were made of linsed oil - it dries on metal but this takes about 3 days)
A short circuit is less likely but possible. Thus I would recomment to check those
electrolytics first when having rather sudden reading-problems.

What was very annoying is the fact that people in the forums only give "known" advices
(like "the solder joints must be broken", "the eloctrolytics /laser is dead") which are close to
urban legends or the doctor´s "take an aspirine and come back later".
What was also very surprising: I used an YEDS-18 Test CD from Sony, which is was a standard for repair shops
and given as required in service manuals.
It served me well on many japanese players. But all those players have conical, spring loaded rings for centering the CD.
Thus a mismatch in the diameter of the inner hole is compensated.
Philips never had this mechanism. As a result the YEDS-18
(costing about $100 btw) had too much play horizontally, more than many ordinary CDs...
But at least I have an completely refurbished CD 304 by now- :music:
 
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Thanks! It took me more than a month while trying everything:
Changing all Electrolytics, changing transistors and all IC´s still available, resoldering everything, checking every cable,
even buying some Philips cheapo players off ebay using the same chipsets as the CD 304 MKII.
I am not so shure whether there was a short circuit, but the mentioned "dry" electrolytics (not tantal, but using aluminium with a dry electrolyte) showed some green rust on the legs.
I did clean the boards half a year ago with water and seal the copper plane with wood oil a week
later (The first paints were made of linsed oil - it dries on metal but this takes about 3 days)
A short circuit is less likely but possible. Thus I would recomment to check those
electrolytics first when having rather sudden reading-problems.

What was very annoying is the fact that people in the forums only give "known" advices
(like "the solder joints must be broken", "the eloctrolytics /laser is dead") which are close to
urban legends or the doctor´s "take an aspirine and come back later".
What was also very surprising: I used an YEDS-18 Test CD from Sony, which is was a standard for repair shops
and given as required in service manuals.
It served me well on many japanese players. But all those players have conical, spring loaded rings for centering the CD.
Thus a mismatch in the diameter of the inner hole is compensated.
Philips never had this mechanism. As a result the YEDS-18
(costing about $100 btw) had too much play horizontally, more than many ordinary CDs...
But at least I have an completely refurbished CD 304 by now- :music:
hi there,
i have a philips cd-204 that is not reading the table of contents,i am going to try the caps that you state,
in fact i might try to replace them all,
will report back
mike
 
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