Rotel RCD-971 Issues - diyAudio
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Old 9th November 2010, 01:45 AM   #1
CR500 is offline CR500  United States
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Default Rotel RCD-971 Issues

Anyone know a fix for any of these issues with an old Rotel.


1. Randomly seems to cut out, almost like a skip, can hear the cd do something funny.

2. When selecting random playback, always starts with track #6. I haven't paid attention to see if the whole order is always the same.

I downloaded the service manual but it doesn't seem too complete (for a service manual). Does anyone have a manual with more than 9 pages? There must be some diagnostic / test modes but the manual doesn't mention any kind of trouble shooting.

Thanks!
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Old 9th November 2010, 07:03 AM   #2
Mooly is offline Mooly  United Kingdom
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Majority of problems are mechanical. What laser mechanism does this model use. eg Philips CDM12.1 or KSS210 etc ?

As for test modes etc, what you need to do is confirm the signal quality from the pickup (the RF or "eye" pattern) to make sure it is clean, of correct amplitude, and with no jitter. Most skipping problems are down to dried grease and lubrication problems, other common problems are worn spindle motors.
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Old 9th November 2010, 07:42 AM   #3
poynton is offline poynton  United Kingdom
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(Unfortunately) This player uses the Sony KSS-213B laser with 2 x PCM63P and PMD100 and is not one of the earlier Philips clones.

Having said that, a replacement laser is both cheap and easy.



Andy


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Old 9th November 2010, 08:28 AM   #4
farl is offline farl  United Arab Emirates
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try to clean first the lens before going ahead with the repair.....

farl
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Old 9th November 2010, 12:18 PM   #5
CR500 is offline CR500  United States
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Yesterday I disconnected / reconnected everything. Issue #2 seemed to be fixed but as soon as I put the case back together the problem returned. Did some more disconnecting, poking / pressing on boards and components w/o success. Also did a close exam for cold solder joints and didn't see any. I was surprised at how dust free the interior of the unit was.

Its still apart so I took a quick look at the laser, its a KSS-213C.

I can see how problem #1 might be laser / transport related, but doesn't #2 seem more likely to be circuit related?

Any suggestions as to cleaning the lens? Q-tip and alcohol? I'll clean and re-grease. What's the suggested lube, white lithium?

Thanks for the help!!
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Old 9th November 2010, 01:39 PM   #6
CR500 is offline CR500  United States
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Ok, the lens looked clean but I gave it a wipe anyway. Connected it up to the stereo with the case still apart and it started out with the common tray in/out leaf switch problem. I've never had that problem :-( Anyway got it to load and part way through the first track it skipped. I'm still on the same disc and it hasn't skipped again yet. I did notice the yoke (#7 in picture) seems to have a very slight wobble.

I'll see if I can find a disc that skips more frequently to see if the yoke wobbles more.
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Old 9th November 2010, 04:10 PM   #7
Mooly is offline Mooly  United Kingdom
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The wobble is be normal as it's a magnetic clamp that centres loosely on the disc.
Problems with grease can be hardening in the teeth of the gears. You need a grease that's compatable with metals and plastics, everyone seems to have their favourites, mine was always,
ELECTROLUBE|SPG35SL|SPECIAL PLASTICS GREASE 35ML | CPC

Always starting on track 6 is down to the player electronics... you would have to ask other users if they do this or not. Electronics are supremely reliable so wouldn't like to say that is a fault at all.
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Old 9th November 2010, 05:42 PM   #8
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Although it is pretty rare on that mech, you should check that the final drive gear to the laser has no broken/bent teeth. On the earlier mechs for KSS210/150, the gear teeth that mate with the laser gear rack would break, due to the spring tension from the upper gear rack over-stressing them. Quick & effective fix, with just a slight sacrifice to 'bump resistance', is to simply remove the upper rack & spring from the laser. While you have the final drive gear off, you should check that the laser moves freely & easily all the way up & down the rails. If you encounter unusual resistance at any point, that'll be a problem to address.

The other & more likely cause for the skipping is carbon build-up in platter and/or sled motor, which can be easily & pretty darn near permanently cured with (specifically)silicone spray lub. You just have to access the slots in the bottom end of each motor to spray the lub into, which, I believe, in your case, means de-soldering the small pcb from the two motors' terminals. One you have slots access, just give a healthy shot of silicone lub into each motor, re-assemble & then play a disc, doing a lot of first to last track skipping to excersize the sled motor. Once each motor has a few minutes of fast running, you're good to go for years.
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Old 9th November 2010, 11:14 PM   #9
CR500 is offline CR500  United States
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Played several CD's today with the case open and it never skipped. A few times it did make a grind noise when play was first pressed.

I did notice that split rack on the laser when I was poking around. Wouldn't it be better to epoxy the two racks for more surface area rather than removing the upper? I didn't see any damaged teeth on the rack or gear.

How hard is it to find a new transport? Or at least some kind of rebuild kit? I'll clean off all the grease and lube it again. I just need to find someone locally that has the appropriate grease.

Thanks
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Old 10th November 2010, 01:12 AM   #10
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If that 'grinding' noise before play was more like a creeking, it's pretty much proof positive that you just need to silicone spray the platter motor, which is what I considered the most likely cause. So, if you just go to an auto-parts store, you should find a silicone spray lub that will fix it right up. The creeking noise is a classic symptom of a platter motor having difficulty starting up.

Although I have never seen one of those mechs actually need replacing, I am fairly sure it's entirely just a stock Sony KSM213CCM, or a slightly different number. Been too long since I've worked on that series of Rotel players to remember specifically, but your exploded view looks exactly like the above number. Should be available pretty cheaply, including laser, from dalbani.com or dalbani.co.uk, or other oem suppliers. But doing the silicone treatment to the motors will make replacement a non-issue, anyway, I am quite sure.

As for the gear rack, the counter-sprung upper is just for the sake of reducing skips from the player getting bumped, and is a 'vestigial organ' from Sony's old discmans. There's no need for the extra gear width, and the player will work perfectly fine without it, although, as you have now observed, it hasn't done any harm to the drive gear and probably won't.
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