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wms
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 Posted: Thu Jan 07, 2010 4:30 pm Post subject: Denon DCD-920 CD-player switches itself off after few second |
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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 |
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vtech
Joined: 08 May 2006
Posts: 1264
Location: USA
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wms
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| Posted: Fri Jan 08, 2010 6:06 am Post subject: |
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| 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! |
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wms
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| Posted: Sat Jan 09, 2010 6:26 pm Post subject: |
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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. |
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vtech
Joined: 08 May 2006
Posts: 1264
Location: USA
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| Posted: Sat Jan 09, 2010 7:43 pm Post subject: |
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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? |
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wms
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| Posted: Sun Jan 10, 2010 6:44 pm Post subject: |
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| 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. |
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wms
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| Posted: Thu Jan 14, 2010 5:53 am Post subject: |
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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:
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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
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I also noticed that IC001 on the little riser PCB (Sony CXD1125, digital signal processor) becomes so hot, I burnt my finger on it  It would seem that the positive voltage supply is overloaded, perhaps due to a problem in IC001?
vtech, does that provide any clues? |
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vtech
Joined: 08 May 2006
Posts: 1264
Location: USA
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| Posted: Fri Jan 15, 2010 2:59 am Post subject: |
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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.
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wms
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| Posted: Fri Jan 15, 2010 4:04 pm Post subject: |
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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? |
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wms
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| Posted: Fri Jan 15, 2010 4:06 pm Post subject: |
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oops, I meant CXD1125 rather than CDX1125  |
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