electronics, repairs, service manuals and datasheets discussion community for the repairs professionals and technicians
FAQSearchMembersGroupsRegisterProfilePM'sLogin/Out
Denon DCD-920 CD-player switches itself off after few second
Goto page 1, 2  Next
 
Post new topic   Reply to topic    Electronic equipment repair and service manual search discussion Forum Index -> Equipment Repairs
View previous topic :: View next topic  
Author Message
wms
Guest





PostPosted: Thu Jan 07, 2010 4:30 pm    Post subject: Denon DCD-920 CD-player switches itself off after few second Reply with quote

Dear experts,

my ~20 year old Denon DCD-920 CD-player worked all the years until now.

Now, after switching it on, the display lights up as usual but goes off after about 3 to 10 seconds. I can open the tray during this period but thereafter the player is dead, as if it had been disconnected from the power.

Could this be caused by aging power supply capacitors?

Thanks!
Martin
Back to top
vtech



Joined: 08 May 2006
Posts: 1264
Location: USA

PostPosted: Thu Jan 07, 2010 11:32 pm    Post subject: Reply with quote

While it can certainly be a cap issue, it may be a connection or regulator problem . Get a diagram and check for missing supply voltage(s)

http://fileshare.eshop.bg/downloadsm/28173/Denon_DCD-920.html
Back to top
View user's profile Send private message
wms
Guest





PostPosted: Fri Jan 08, 2010 6:06 am    Post subject: Reply with quote

Thanks very much for the hint regarding the regulators. Their heatsink is very hot and the voltages are not stable. Will try and replace them!
Back to top
wms
Guest





PostPosted: Sat Jan 09, 2010 6:26 pm    Post subject: Reply with quote

Hhm, I replaced the regulators as well as the smoothing caps upstream and downstream of the regulators but, unfortunately, to no avail.

Any other suggestions are highly appreciated. Thanks.
Back to top
vtech



Joined: 08 May 2006
Posts: 1264
Location: USA

PostPosted: Sat Jan 09, 2010 7:43 pm    Post subject: Reply with quote

Like I mentioned, get the diagram and post back your voltage readings.(plus/minus 5, 10 V etc). I have never been a fan of shot-gun approach.

Is the processor running? do you have clock, any data, reset pulse? How about the -30V for display?
Back to top
View user's profile Send private message
wms
Guest





PostPosted: Sun Jan 10, 2010 6:44 pm    Post subject: Reply with quote

vtech, thanks very much for your replies. Equipped with only a voltage meter I probably won't be able to determine whether the processor works. I'll post the voltage readings once I get back to the player.
Back to top
wms
Guest





PostPosted: Thu Jan 14, 2010 5:53 am    Post subject: Reply with quote

All right, I finally had the time to check the voltage readings. With reference to the circuit diagram (thanks!), the stabilised voltages at the output stage of the power supply are:

Code:

nominal :  actual
+10 V   : + 8 V
+ 5 V   : + 3 V .. + 4 V varying
- 5 V   : - 5 V
-10 V   : -14 V
-30 V   : -30 V
 


I also noticed that IC001 on the little riser PCB (Sony CXD1125, digital signal processor) becomes so hot, I burnt my finger on it Sad It would seem that the positive voltage supply is overloaded, perhaps due to a problem in IC001?

vtech, does that provide any clues?
Back to top
vtech



Joined: 08 May 2006
Posts: 1264
Location: USA

PostPosted: Fri Jan 15, 2010 2:59 am    Post subject: Reply with quote

Based on what you are describing, it all points to the shorted processor and the cause of overload on the 5v line.( bet if you were to isolate the VCC (pin 33 &/or 73 or pin 1 of the connector) going to the IC001, you would get the 5 volts back.
More likely the replacement of the IC will restore operation provided you are experienced/equipped to deal with surface mounts. (or even worthed?) CXD1125 used to be an expensive processor but not anymore.

Back to top
View user's profile Send private message
wms
Guest





PostPosted: Fri Jan 15, 2010 4:04 pm    Post subject: Reply with quote

Hhm...the CDX1125 seems to sell for $50 or more on some websites, which is quite a bit of an investment for this old (but arguably good quality) Denon player. I doubt, however, that I would manage to solder the IC in. So there probably goes my player. I could be lucky and find another broken Denon from which I could take the whole little riser PCB with a CDX1125 on.

Just out of curiosity, is it common for such a processor to die with a short circuit?
Back to top
wms
Guest





PostPosted: Fri Jan 15, 2010 4:06 pm    Post subject: Reply with quote

oops, I meant CXD1125 rather than CDX1125 Confused
Back to top
Display posts from previous:   
Post new topic   Reply to topic    Electronic equipment repair and service manual search discussion Forum Index -> Equipment Repairs All times are GMT
Goto page 1, 2  Next
Page 1 of 2

 
Jump to:  
You can post new topics in this forum
You can reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


eServiceInfo on FB - Service Manuals Free Download - Service Diagrams

Free TV Schematics Download - HARDW.net - Pinout Master - Jabse Search - Jabse.InK  - Pulsator

SnimkiOt.com - Poblizo.com : пътешествия