b&o cd-x

[guido]

Hi,

Picked up a B&O cd-x for little. Broken but worth the gamble
(15E). It is one of the first cd players around, cdm-1 transport and SAA70xx chipset with 2 times TDA1540. I am not sure yet if i can use it or just keep for parts, i'll see.

It is broken, somewhere there is a problem with the powersupply for the main pcb/cpu. Looking into that now, but some schematics might help :->

Anyone with schematics for this machine or the Philips CD104 (~equal machine) ??? Or more general, information on this chipset and some schematics of the digital decoder/filter and/or analog part (some linetransformers are used)??

Thanx in advance,
Greetings,
GuidoB

[guido]

Got some life into it. Somebody poked around before me.
He/she managed to connect a powersupply connector to the output connector (output wires are direct connected on the pcb, so that connector should be empty). Since the output is connected to transformers there were some nice effects.
Ever seen -3V on the output of a 7812.........

Anyway, fixed that and a vapoured pcb track and now it does something: display switches on to '0000' and there is some reaction to play and stop: the display goes off for a moment.

However, no reaction on eject, so i think that the four connectors from the switches and the motor are also not connected correctly.
Guess if you could connect PS to the output, you could easily do something wrong there. They are on a small pcb nect to the main one, near the on/off switch. All are 3 pens.

Anyone with such a machine who could have a look inside????

Thanx
GuidoB

[guido]

hi,

i was right, there were more connectors swapped. After i got the information from someone (love the net), i got the thing to play again. Works well, no hickups, plays all..!

What is it:

- CDM1 transport, impressive piece of fine mechanics
- 2 times TDA1540 14 bit DACs with SAA70xx chipset (the first)
- 6 kg weight!! Huge metal subframe inside
- great looks, mechanised opening/closing

GuidoB

[frenzic]

I have one to. It doesn't play high (40x and more) speed burned cdr's. It does play the older ones, though. I'm not sure if it's got a dirty laser or that it might lack the power to read cd's written in the modern fashion. I also own a cd502 (for 11 years now, never failed) with cdm4. This reads anything. Does anybody know if that should be the same with cdm1? How's your cdx playing these burned cd's?
regards
frenzic

[jean-paul]

It doesn't play high (40x and more) speed burned cdr's.

Burning audio at 40 x is not the smartest thing to do.

Even with the best cd-writer it is much better to burn audio at 8x or preferably even less. Just burn one at 4x and compare it to the one written at 40x. The BER is also higher when writing cdr's at higher speeds. Something you don't want when you are after high quality of sound. Burning data is something else and can be done at higher speeds.

Especially reading of the original cd should be done with lower speeds to the harddisk instead of writing "on-the-fly". It'll avoid the plops and cracks you hear on cdr's written by people who don't know how to write audio-cdr's correctly. The plops and cracks are caused by the cdrom/dvdrom that spins at high rpm and fills the buffer, when the buffer is becoming empty the spindlemotor will suddenly spin up at high rpm and it will fill the buffer again causing the unwanted side-effects.

When reading the original cd it is also wise to do nothing with the pc except for waiting till the cd is read completely. Again, that only counts if you go for quality.

Common knowledge but still very true...

[guido]

Don't know,

My burner only supports 2x..... On the other hand, i got it for free and it never fails. I don't need 40x, i press record and do something else without computer..

Guido

[guido]

And btw, there are no transformers in the linestage. What i saw are relays. Seem to some kind of reed relays (glass tube) with the coil around it; looks like line-transformer.

Yes! Mute and deemphasis done with relays l! And that for '84.. Got NE5532 though, but i don't think i'll start upgrading.
It is fine as it is, a playing artifact.

Cannot use it for my dac either: no room inside and the master clock is ~4.4Mhz. Time for a cd-x 2 :->

GuidoB

[frenzic]

@ Jean Paul

Indeed all of that's common knowledge. I actually have an audio only dedicated pc so that I do not lose any computing time on my regular workhorse and I get as little interference as possible. What I ment is that these days cdr's are written like cdrw's. A laser needs to be of higher intensity to read these tracks. I wondered if a cdm1 laser could do that. Because my cd-x doesn't.

[jean-paul]

I have one to. It doesn't play high (40x and more) speed burned cdr's.

What I meant is that these days cdr's are written like cdrw's. A laser needs to be of higher intensity to read these tracks.

I am not sure what you mean, because you clearly wrote that it doesn't play 40x speed burned audiocd's.

Maybe you mean that cdr's reflect 50% compared to a normal cd and a cdrw reflects 25% compared to normal cd's ? A cdrw is NOT written like cdr as the technology differs. Certainly the high speed CDRW burners write with a technology that uses phase change techniques ( which in fact came from MO drives ). The format is also different, most of the time they're written in the UDF format.

CDM1 nor CDM4 don't have problems with cdr in general when they're in good shape. Some even read cdrw although they shouldn't play them because cdrw didn't even exist in their days.
When cdrw's are written like cdr's (which is possible of course ) my cdm's don't have a problem with them.

[zygibajt]

I use to have B&O Beogram CD 50.It was looking great.Sounded strange,not that bad like for 1986 year player.I remember it's mechanics,wonderfull,extremely well built,all bearings,all steal,almost no plastics.
Bartek