Grundig cd7500

[bosetuno]

Hi!

I almost new to the forum, maybe I posted a couple of times but I even did not remmember! I will fisrts introduce me.

I am not a electronic eengineer, but actualy I am a sound eengineer, so I have some electronics knowledge, but to be honest, I just undestand quite simple Tube amps electronics. I don´t have experience with digital things.

Well, to the point. I got a Grundig CD 7500 from a garage sale, but unfortunately it does not work. It powers and lights but the LED does not. Nothing to worry yet.

Here comes the worst. The cd does not move and on the output there is a lot of noise, kind of brown noise. I´ve been reading for a couple of days on forums and the noise could be caused by a faulty power supply. But I did not found any suggestion about the cd transport. The weird thing is that when I turn the unit off, the cd moves for half second.

I measured the transport engine and no voltage appear on normal and a 2.6volts spikes appear when the unit is disconnected.

Please, I need spiritual advice on this one. And a schematic!

Thanks

Carlos

 

[danico]

Hi there!

You can have the manual from here:Service manual, eprom result list | ElektroTanya | Service manuals and repair tips for electronics experts

Look for the philips cd-303, its allmost identical. Acording to this site
Steerpike's Toys
" Based on a Philips CD-303, but with improved DAC & Decoder board (NO Sony chips in here!), and a special uniquely Grundig grounding layout.
It was broken when I got it, not reading discs at all. But a replaced 6n8 capacitor on the servo board restored it to full functionality. The cabinet was very badly scratched, but is getting re-painted, and new wood side panels (instead of original plastic).
It has the highly regarded Philips CDM-0 mechanism & optical unit, and TDA1540 D/A converters, which are also reputed to sound special. It really does sound GOOD!

I hope you can fix it, this is one my favorite player.
Just messure the voltage from the regulators,probably a bad cap.

I fined the treat ,too:http://www.diyaudio.com/forums/digi...3-radial-servo-malfunction-advice-please.html

 

[bosetuno]

Hi Danico

Thanks a lot. I will now check the schematic to see what component may be interrupting engine voltage.

 

[amc184]

Hi Carlos,

That's a nice CD player you've bought, hopefully you can get it going. The Grundig CD7500 is actually exactly the same as a Phillips CD303. The CD303 had two versions; one with a mixed Philips and Sony chipset and one with a complete Philips chipset. I've owned a CD303 with a Philips only, and I too bought it broken (and later fixed it). Unfortunately, though I looked hard, I never did find a service manual that covered this version of the CD303.

There are two things that I would look at on your player:
- The electrolytic capacitors. These components will have long since died. If you're serious about fixing this player and keeping it afterward, I would replace all of them. If you aren't keen on that idea, start with the ones in the servo, particularly the ones on the PCB attached to the laser mechanism itself.
- The silver axial film capacitors. Though film capacitors are generally reliable, there are a certain type of silver axial film that Philips used in these player that can go open circuit. This is the 6.8nF capacitor that Steerpike mentions in the site Danico linked to.

Good luck with your player.

 

[bosetuno]

Hi

Thanks. I had planned to do a complete recap, but first I wanted to know if the motor was broken. I will do a recap of the PSU and the Laser PCB, and then see what happens.

Cheers

 

[bosetuno]

Thanks

I will try to recap it in parts to see what happens.

Cheers