philips cd303 waiting to be repaired

[matti-ilmari]

I have philips cd 303/00 player (silver) and I`m wondering if it is repairable. It plays well for a while, but suddenly there´s only noise. kind of electrical noise that really hits your nervous system.
I dont know anything about this player and only place in the internet where I could find anything about this player was this forum. So I´m hoping get information about this player, if its any good, if there is any sense in getting it repaired. I am not able to repair it myself, but I would not mind getting some repairing tips to make it easier for a friend of mine to repair it. Anyway it wood be very interesting to know something about this player.
Thank you for your help.
Matti

[Thomas]

Hello Matti.

I can tell you a few things about this player. First thing is, if you are not able to repair it, you can allways sell it to me.

The player has the wonderfull CDM-0 laser unit. You can search this board for lots of CDM-0 and CDM-1 repair tips (they are the same, almost). But, the problem you have sounds like bad solder joints. Philips is known for solder joints loosing connection over time. This is easily fixed with a touch-up by some new quality solder added to the joints. Again, use the serarch. There are lots of information about this on this board.

[Tim Foster]

Hi Matti, just wanted to help you out with your cd player.First hang on to it as they are a great machine it's one of the first 16bit cd players that philips produced and are highly regarded as one of the best cd players for playing difficult cd's scratched etc. As for the problem it is the ram ic causing the noise ,fortunatly you can still get the ic which is an MSM2128 or sometimes philips fitted a TMM2016P but they are both identical just differing numbers also the later of the two was used in the teletext pcb of some philips tv's. You will find the ic on the small sub board on the top panel . hope this helps you if you haven't already got it fixed. Tim

[guido]

Hi,

According to my repair database (euras), this thing has 1540's. So a 14 bit machine. And that the thing is silent if the ram goes dead. But it's only paper, dont know the machine myself.

Nothing for noise with this machine, but a lot of similar players start to generate noise with a broken 18V powersupply reg. Maybe it has a bad connection Start there, easy to check in a min.

Check also pen 38 of SAA7020 if it is really 0V. In case it has a bad contact it's 3.8 and you could get noise.

More noise with SAA7220, it is temp sensitive and makes the machine to generate noise. But that chip should not be in there.

Good Luck

[adx]

It uses 14 bit DACs but is 16 bit with upsampling (in the olden days this was called "oversampling" and noise shaping). This is before they went all the way to 1 bit.

I could make mine make the most horrible imaginable noise (full scale white noise) by disabling the error concealment / muting. It actually relies on this to keep the player quiet when the disc isn't playing. This is a line which goes from one of the chips to another (how's that for useful!) so could have gone open if that is what it sounds like. Long shot!

I like the mechanism. It reminds me of a gantry crane or whatever it's called - the type used to transfer 100s of tons of steel around a warehouse, that runs on beams up in the roof. Meaty.

Anyone know of any mods?

[m127]

Hi all,

I also have a problem with noise but it's a different player: an Onkyo DX-6750. Everything is normal with original cds, good eye pattern, nice tracking and focus signals, good sound, fast toc reading, playing without skipping, quick seeking.
But, when trying to play cd-r discs, its sound becomes distorted. On the oscilloscope it looks like the signal is "stepped". The interesting thing is that the reading performance is still Ok, as I said with cds above. I cannot figure if it's the transport or other parts defective, and if the transport is, then why can't I see it on the signals. Everything looks the same, just the sound is distorted. Any ideas on that?

[adx]

It might be incorrect EFM encoding or frame construction - I know some CD recorders have that problem. This could cause the player to have continuous C2 errors (?) and would reconstruct half of the samples either by repeating them or linear interpolation. Could be it?

[m127]

Yes, I think what you say can be the problem, though I don't think that disappearing of half of the samples is enough for one to see the stepped form of the signal on the oscilloscope. Anyway, is there a way to test this? And why does the type of the disc have any influence on that? This is the most interesting aspect of the case for me, I just can't see if it's the transport or the chipset causing the problem. On the other hand I think nobody has tried to fix this player yet, so this problem must have started as a part of the normal wear. Doesn't sound like a chip problem to me. Am I wrong?

[m127]

Oh, I just got the point, are you saying that the player may not be defective at all, just old enough not to be able to play cd-r discs by not "knowing the theory"?

[adx]

Yes, well actually more a fault of the recorder than the player. If you're getting a good eye pattern and nothing unusual in the servo signals, then there is nothing else to differentiate between a stamped CD and CD-R AFAIK. (I really don't know for sure.)

I'd try playing discs from drives which are known to "do proper EFM encoding" or whatever ou see on reviews of CD-RW drives, this could have something to do with it.

If every second sample is being reconstructed, then the player won't be able to play a 20kHz test tone, it will be aliased down to 2.05kHz or something, and I'm picking the waveform will look a bit steppy even trhough a sigma delta DAC.