Peter Andersen wrote:

Hej alle

Jeg har et Beosystem 2500 stående der ikke vil læse CD. Den har lidt sit eget liv, laseren vipper op og ned, spindlen kører lidt rundt, og "ryster" mens den kører baglæns og kan pludselig finde på at køre på fuld drøn, dvs. meget hurtigt rundt helt ukontrolabelt. Alt sammen uden at vil læse CD'en på noget tidspunkt.

Er det dårlige lytter eller skal der en ny laser til? kan der overhoved skaffes ny laser til 2500?

Peter

Det kommer lidt an på hvilken laser den har. Er det den kurvede eller lige version ? Den kurvede er det sjældent laser der er problem på, men er det den lige laser, så skal du finde en ny. Det er nok en CDM 12.4 laser du skal finde, men du bliver nød til at finde ud af hvad den har først.

/Jacob

Det er den kurvede jeg har. Den sidder under spindlen og drejer, til venstre, om sin egen aksel.

Jeg har målt lytterne efter på CD boardet, og der er ikke nogen der umiddelbart fejler noget (værdi og ESR værdi).

Hi,

sorry to answer in english.

The Beosystem 2500 with the curved laser has the CDM 4 unit installed. So the problem is caused by the famous 'C2103' to 99%.

In the Beosystem 2500 units it's C100 on the CD Servo Motor System and Disc Detector Board. replacing the electrolytic capacitor with a new Philips / Vishay blue capacitor and the fault should be gone.  C100 is connected to Pin 17 of the TDA 8808T and ground  in the '2A' area of the board.

Maybe Dillen (Martin) can provide a capacitor for you.

Hi

Ok, thank you. I replaced it with a Panasonic FR capacitor, and the laserarm is steady and it seems to have cleared the problem. BUT not completely: it makes a rattle sound, turns a few times around, makes a rattle sound, and then stops.
Look here:

https://www.youtube.com/watch?v=rZv_xO8JWBM

Peter

That rattling sound is most probably caused by the laser diode itself, when trying to get the focus.

Every CD drive works as follows:

-move laser unit to innermost position.

- is CD installed? Switch laser on and see if it gets reflected.

- If reflection is found, spin the CD

- now try to get a focus on the surface of the CD. (This is done by moving it up and down)

-If focus found move to position of TOC ( Table Of Content) and read the table.

-play first track if not otherwise specified. position of tracks is contained in the TOC..

So i think it still doesn't get the correct smoothed and filtered current for the laser diode. Try to get an original Philips / Vishay capacitor.

Up to now noone ever found out what is so special about this capacitor from the manufacturer😮 Atleast no one ever told the secret.

Make a search here on the forum 'Workshop' about 'C2103' or 'Vishay'. Nearly all problems are fixed by using a blue Vishay cap. (

Hmm, it sounds very strange. I am an electronics technician, and the Panasonic FR is the best quality 105° low-esr capacitor you can get. The original cap. is a low quality SAMHWA capacitor like almost the rest of the caps in the unit. It is not a Philips cap.

The problem must be related to something else, or a bad laser? I can see that the sound is a mechanical problem cumming from the spindel/cd and is not related to the laser. It makes the same sound when i turn the CD around with my finger.

Those 'old' radial drives are built like rock. As long as you don't play around with the laser current they work flawless and the laser itself lasts nearly forever.

See here what user Dillen (Martin) wrote about the capacitor:  link

Here's a little 'dispute ' about the capacitor 

Ok, great. The FR and FM are the same capacitor, FM are just for only 2000-7000hours where FR are for 5000-10.000hours.

But anyway, it it not that problem i have here. The spindels runs backwards at full speed. I also notised that the trimmer was turned full CW (as seen from the solderside) - pretty strange.

I think I have to get Martin to look at it.

I wish people would stop focusing on low-ESR. It's as if low-ESR is the best thing in the world.
It's not.
In some circuits using low-ESR will be fine but definitely not in general.
In some circuits, like f.e. DC-coupled output stages with a certain amount of feedback, they can really mess things up and
cause self-oscillation, ending in heat and smoke and elaborate repairs.

Use a blue Philips/BC capacitor and forget about the "trendy" Pana-stuff. Works every time.
(And the talk on other fora about it affecting the sound quality is rubbish).

Martin