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Old 4th February 2004, 03:15 PM   #11
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so... the power supply seems ok. i noticed that the lens is not stable, even when it can track... and that with the focus offset trimmer at approx. middle course. i tried to verify the red light emission on the lens using my dark-room light-meter, and the diode seems in healthy condition. i guess i should begin to play with focus offset....
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Old 5th February 2004, 09:21 AM   #12
EDUM is offline EDUM  Netherlands
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While tracking can you get sound after pressing the play button a few times?

Check while playing if the small relais in the audio output are on or off.

Ward
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Old 5th February 2004, 10:15 AM   #13
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Default Service Manual CD 303

Hi Guys,

I'm not 100% sure if it's from a CD303 but I think I have a copy of the SERVICE MANUAL.
If that's the case, I'll be happy to copy it for you Federico.

The only problem is, it's in the garage in one of the 8? or more boxes.
As soon sa I get my hands on it, i'll copy it and send it for you.

I don't have a scanner ider, so you'll have to wait for me to copy it.

Best regards,


Audiofanatic
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Old 5th February 2004, 10:10 PM   #14
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Thanks. audiofanatic !
it would be marvellous!
I did not try to check the state of any relays yet...
if i move my finger from the spinning disc, it begins to run too fast and it does not track anymore...
and the digital-analog part of the player is fortified (shilded) as a tank! (would take a while to get uncovered...)
I tried to play a bit vith focus offset and gain, but in the end i restored the original condition. i did not tuch the diode power.
the spindle just does not sit at 500 rpm. i guess there should be some sort of feedback between motor voltage and the disc speed, but i can't understand how it should work and where the problem is... maby even not in the transport itself?
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Old 6th February 2004, 10:10 AM   #15
guido is offline guido  Netherlands
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Quote:
Originally posted by elperopu
Thanks. audiofanatic !
it would be marvellous!
I did not try to check the state of any relays yet...
if i move my finger from the spinning disc, it begins to run too fast and it does not track anymore...
and the digital-analog part of the player is fortified (shilded) as a tank! (would take a while to get uncovered...)
I tried to play a bit vith focus offset and gain, but in the end i restored the original condition. i did not tuch the diode power.
the spindle just does not sit at 500 rpm. i guess there should be some sort of feedback between motor voltage and the disc speed, but i can't understand how it should work and where the problem is... maby even not in the transport itself?
Remember,

If you get it working, you can only use it as-is. It's 14 bit dac's inside, removing the filter to go non-oversampling is not possible:
16 bit data going in the filter, 14 bit 4x oversampling going out.

It might be possible to connect 1541 BEFORE the filter in the mode where there is one pin for left and one for right data. But that is as far as i know not tested by anyone yet (there is a post on it, search).

But you will find that there is not so much space inside for modding. And no I2S to connect stuff to. Don't know if there is spdif in there for dig out.

One of the relays does muting, so it might be the reason for no sound.

Greetings,
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Old 6th February 2004, 01:15 PM   #16
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Thanks Guido!
the possibility co connect a 16bit dac is very appealing!
I will try to sort that post out...
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Old 6th February 2004, 04:52 PM   #17
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I found that post...
i will mabe give it a try if i can only get it working...
what is involved in the speed control? i guess i must check connection in that path, but i don't know where to look at.
does also have the reciever somthing to do with it...
thanks federico
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Old 9th February 2004, 07:35 AM   #18
EDUM is offline EDUM  Netherlands
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Hi elperopu,

First comes Focus, second is radial Tracking, third is tangential tracking (speed).

As it is difficult to do a long-distance repair I sugest you get the manuals first and go through them step by step. That way you learn how the player operates. This makes a repair far more easier. It certainly is worthwhile to repair it.

If you have questions left then contact me

Ward
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Old 10th February 2004, 06:57 PM   #19
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A nice member has just sent me the manual! great!
i will go through it and report.
thanks to all of you!
federico
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Old 21st July 2004, 01:22 PM   #20
adx is offline adx  New Zealand
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Quote:
Originally posted by guido
If you get it working, you can only use it as-is. It's 14 bit dac's inside, removing the filter to go non-oversampling is not possible:
16 bit data going in the filter, 14 bit 4x oversampling going out.

It might be possible to connect 1541 BEFORE the filter in the mode where there is one pin for left and one for right data.
...
I have a Philips CD303 and once (a long time ago) put a switch in to enable and disable the oversampling filter (or upsampling processor as it would be called nowadays...).

From what I remember: The oversampling filter generates 3 out of every 4 samples. By switching the DAC clock over to before the filter chip, you can ignore these extra samples, and change from 16 bit 4 times oversampling (noise shaped) down to the original CD data at 14 bits (truncated I assume). It was easy to work out what to do from datasheets. I verified the steppy waveform on a scope too.

Strange thing was I couldn't hear the difference, even though there should be a dropoff in high frequencies due to the sinc response, not to mention the 14 bit conversion. (I remember writing this before, so there might be a usenet posting somewhere.) This was all done around 1990 with a pretty early DIY system, so maybe I should drag that player out and try again (on a newer DIY system - I've never had a "real stereo"!).

Another thing I did was disable the error correction. There were 2 surprises: 1 being the awful full scale noise when in stop mode due to random data from the pickup not being muted. 2 being the fact that very few discs actually had any errors at all on them - the odd sharp tick being audible when it did happen (I checked that with a scope too).
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