Sony CDP790 and KSS240 Restoration Project - Page 2 - diyAudio
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Old 26th December 2012, 10:54 PM   #11
ide2003 is offline ide2003  Indonesia
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Thanks Mooly, things that I've always want to know but never found , got to get that scope someday, just replaced my Sony CDP950 kss210A, trial and error way..still not right
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Old 27th December 2012, 12:29 AM   #12
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Some good tips on adjustment, with or without a 'scope, here

My tip: when listening up close, be careful your hair doesn't get caught up in the mech.
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Old 27th December 2012, 07:55 AM   #13
Mooly is offline Mooly  United Kingdom
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Quote:
Originally Posted by ide2003 View Post
Thanks Mooly, things that I've always want to know but never found , got to get that scope someday, just replaced my Sony CDP950 kss210A, trial and error way..still not right
Pleased it was of help.
It's always possible your new KSS210 is dodgy (again a scope would help confirm that).
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Old 30th December 2012, 01:15 AM   #14
ide2003 is offline ide2003  Indonesia
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thank you guys for the link & tips. CDP950 uses kss150, have replaced with original salvaged kss210 twice with no problem, only this time with new 'original' kss210, i'll watch my hairs though

happy new year!
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Old 31st December 2012, 08:46 AM   #15
Mooly is offline Mooly  United Kingdom
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While looking at possible changes/mods/improvements to the analogue circuitry a couple of possible issues came to light. More poor soldering. The pictures say it all. The component leads were just flush with the surface of the PCB. A bit of upward pressure and the parts would detach. This type of defect was surprisingly common in the industry generally around this era.

Click the image to open in full size.

Click the image to open in full size.
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Old 2nd January 2013, 11:03 AM   #16
Tomom is offline Tomom  Australia
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Is LC7881 actually also ladder type DAC?
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Old 2nd January 2013, 11:40 AM   #17
Mooly is offline Mooly  United Kingdom
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Quote:
Originally Posted by Tomom View Post
Is LC7881 actually also ladder type DAC?
It seems to be a combination of technologies according to the data sheet. I wouldn't like to try and label it tbh.
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Old 4th February 2013, 09:26 AM   #18
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A fascinating and timely thread - from my point of view at least. I only wish I understand most of it but sadly it goes way over my head and I don't have access to a scope or even a test CD. I do have a soldering iron and would be prepared to check for and rectify dry joints and will reseat the ribbon cable.

I have a fairly old, long unused Sony CDP-790 CD player; when attempting to play CDs, it "jumps" back at various points - e.g. going from 10 minutes 22 seconds to 10 minutes 23 seconds and then back to 10 minutes 22 seconds again, after doing this a few times it moves on, only to do the same sort of thing later on.

I have opened up the case and can see no obvious reason. I had considered working the mechanism back and forth a few times to make sure that it was moving freely, putting some light machine oil on the shaft and cleaning the laser lens with IPA and a cotton bud. However, I don't know what I am doing and would rather not make things worse than they already are.

Do you have any suggestions as to what I might try? It is quite a handy spare CD player with some handy facilities (the variable output) and I would rather not consign it to the skip. I would be very grateful for any advice you can offer to someone who has nothing like the expertise and experience that you obviously have.

Many thanks in advance

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Old 4th February 2013, 10:39 AM   #19
Mooly is offline Mooly  United Kingdom
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Pleased you found it all useful

First thing has to be to clean the lens. It should look bright and shiny with a bluey tinge under a stong torch light. I know ISO (IPA) seems to get a universal recommend as a cleaner but its something I would never use on optics tbh. In the early days Sony even issued a warning to that affect saying that ISO could damage (the then newly introduced) "coated optics". Camera lens cleaner perhaps or just warm water with a single drop of detergent mixed in.

I doubt whether the sled is sticking tbh but that said you have to consider the possibilty. Monitoring the voltage across the sled motor in playback is a good clue. If it suddenly starts to rise its a good indication the sled has stuck. The voltage will keep rising until the motor overcomes the friction and the sled jerks forward.

Most likely is a faulty pickup. The KSS240 was notorious for giving trouble. A replacement should work straight off and is easy to fit.
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Old 1st March 2013, 06:48 PM   #20
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Good news on the sticking front. With the demise of Jessops, I had real problems sourcing camara lens cleaning liquid. Having managed to find some, I carefully cleaned the lens as advised earlier and left the CD player on repeat overnight (Karajan's Beethoven's 9th - DGG) and it now works absolutely perfectly on anything. Thanks all round


As an incidental follow-up - I have subsequently found a CD/DVD cleaning disk on eBay (Omega DVD-15) that includes cleaning fluid.
Are these things safe?
Would it have worked satisfactorily?
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