Rotel RCD975 delayed play - diyAudio
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Old 15th February 2009, 04:40 AM   #1
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Join Date: Jul 2008
Default Rotel RCD975 delayed play

Hello all, it seems to me I just come here when my RCD with CDM9 mech has issues. Im not sure I wont be coming quite often as Im NOT giving up on it

Having fixed the drive eject issue with the gear thanks to this forum, I now have an unusual little issue. Ive hunted hi and lo and I can only assume its something uncommon, or just age related.

There seems to be no pattern to it, but in general, if I insert a CD, it'll read the TOC fine, but when I hit play it'll come up with the track number, and play symbol, and sit there. The CD doesnt move.....it sits there until, well, it decides its time to play, then it plays perfectly and doesnt stop.

Sometimes I can stop it, and it'll do the same, or it'll start fine. Its all over the place. Im not familiar with how these hang together. I've checked all connections, ribbon etc, and all seems fine. I keep thinking either the motor has an issue (but yet it runs fine and starts fine when it wants to) or....well I could make suggestions but I really have no idea.

Anyone seen something like this?

Thanks for any help.
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Old 15th February 2009, 07:48 AM   #2
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Join Date: Dec 2003
Location: Sydney
I had silly issues with some top end CD transports where the spindle motor commutator was dirty and was shorting the rotor's sections - limiting the (start-up) torque. These transports usually have quite heavy puck as well to make things even more torque demanding. I had to take the spindle motor out and wash the whole motor in methylated spirits. I actually "injected" the methylated spirits with a syringe - under pressure). This worked wonders (did the same thing many times with DVD players as well...) You may have to do the same... hard to tell.

Needless to say, the first time I had this specific problem it took me couple of days to try to narrow the possible cause - everything measured okay and was mechanically okay ...!!!

Remove the top cover and observe what's going on. If the TOC reads okay and immediately after the tray closes then it could be something intermittent (contact or issue with electronics somewhere...) or mechanical. If the disk won't spin, give it a bit of kick-of with a finger. This will help you narrow the possible cause of the problem. It may be the weak laser. You'll need to measure this first to be sure. I have posted already how to do this before, so try the search engine.

Just don't spend $50 - $100 for a brand new mechanism straight away... do a bit of fault finding first.

Good luck,
Boky
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Old 15th February 2009, 08:01 AM   #3
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Thanks Boky, yeah I had the cover off yesterday and the TOC reads straight away and first time every time. Every time I turn it on, the TOC comes up instantly. Its only when it goes to play that it hesitates.

Actually I just tried it again, switched it on and the TOC came up instantly. Pushed play and the track count of 1 came up and the play symbol, no track time. Oddly, it counted off track 2, then track 3 (no CD movement still), but then decided to play starting off at 3. That was after a minute or so. And now its happily playing perfectly again, shifts tracks back and forth instantly. Stop it, it starts again fine. Eject it, it plays fine when reinserted.

Ehhhhhh Im totally flumoxxed. I could take it in but where would be the challenge in that!!!!
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Old 15th February 2009, 09:26 AM   #4
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Join Date: Dec 2003
Location: Sydney
OK. It sound like there is thermal problem - either a cold solder joint or something's wrong with servo chipset. More likely a cold solder joint on the board somewhere. Look for 2 things:
1. Signs of overheating, black spots and similar.
2. Transistors on a heatsink - if soldered first AND THEN screwed on to a heatsink

You can still wash the spindle motor with methylated spirits to narrow down the possible causes.

You can get a freeze spay-can and try to cool one component at the time - see if anything is overheating... basically, if you spray the offending component, the player will immediately start playing correctly.

Does it always read TOC irrelevant of the period after being switched on? The TOC read function does not fully engage the tracking, focus and spindle servo... it is fully engaged only while in play mode (TOC is located at pre-defined radius distance from the center that requires constant and known speed)

And one other thing: try to spin the CD with your finger if it won't start, like I already suggested....

Boky
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Old 16th February 2009, 12:23 AM   #5
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Join Date: Jul 2008
Well I think I have this problem isolated, if not licked.

And I guess all my efforts in removing the top and bottom plates 10x made no difference.

I removed the player and put it on the kitchen bench. Flawless. Thought maybe id moved or flexed the board or something...but repeated shifts said it works flawlessly in the kitchen, not so hot in the lounge.

Seems my answer is a fussy power supply and some sort of voltage drop from my HT gear hanging off the 3 power sockets I have there. I can only assume they're all hanging off the same feed....I can now make the Rotel work as well in the lounge as well as it did in the kitchen by switching off the plasma.

I think I need some decent power for this gear from my distribution box but it begs the question, should the Rotel P/S be so fussy with voltage drop or is it a sign its getting long in the tooth?

Thanks for all your help Boky....
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Old 16th February 2009, 06:31 AM   #6
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Join Date: Dec 2003
Location: Sydney
All devices and appliances have to comply with standards when it comes to harmonics they feed back in to mains supply. Isolation transformer and ferrite rings around the CD Player power cable should fix this.

It is very unlikely that plasma generates RF / harmonics that would cause this. The mains feed to the plasma screen is well filtered before SMPS. Event further, your problem is intermittent and "time-related". I think you may have a cold solder joint somewhere on the PCB caused by overheating and / or mechanical stress. You also may have to check all ribbon membrane cables / connectors.

It may be the close proximity of the plasma display in regards to CD player placement that is causing the problem....maybe...

Try only one thing at the time - otherwise you'll be confused and will be unsure if you fixed the actual problem.

Boky
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