Help re laser and mech Rotel cd971

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Hello, I am very much amateur regarding electronics. Bought a modified Rotel 971(mains filter, audiocom clock, with separate regulated power supply,opamp upgradeLM6172), which sounds wonderful. Problem is that it has started to skip badly, and is very tremor sensitive. At times it simply stops producing sound , and the digital time display stays the same, at other times it will do dramatic skips. Driving me nuts! I strongly suspect a laser issue, and as this assembly had in fact been doctored by trying to turn it into a top loader(now back to original configuration)I think its likely to be some sort of mechanical issue here. I have checked and lubed etc- no good. Buying a new laser and mechanism is possible, but I was considering stealing something out of another player. Does anyone have any suggestion re finding cause of this issue, and /or can anyone tell me of other cd makes and models which use this same assembly-Sony KSS213C (this is the designated code for pickup-I note my player has 213B,dont know why,or if this would make a difference).It appears that KSS213ccm might be the code for the whole mechanics and pickup. I am reluctant to spend another $100 on this spare part when I dont know if it will fix the problem or not! I would very much appreciate any help. And yes, I do know I am probably way out of my league, but its been a good learning curve.
 
The KSM213CCM complete mechanism w/laser is available for $9USD at dalbani.com & for $22USD at dalbani.co.uk, and should certainly cure any issues with the Rotel.
However, if the top loading modification has added a "hockey puck", i.e., need-to-place-by-hand disc clamper, and it is not dynamically balanced & with solid centering(i.e., to prevent shaking/vibrating during rotation), this may be the cause of skipping and/or the cause of premature platter motor death. Good top loaders of this style, e.g., Sony SCD-1/777, have such balanced pucks, which lock solidly on center of spindle when placed. Not an easy task in an aftermarket modification environment.
 
you might need to check the eye pattern and adjust for best result using high speed scope,

but it should works ok without adjustment.

do not mod it to become a top loader, the height adjustment on the spindle is critical, better not mess with it, or you will have focusing problem.

another tip is to remove the lens mechanism plastic cover, to reduce resonance when the laser is tracking, the plastic cover is very wobly and vibrates . you might get more dust though, I simply buy some laser since it's so cheap for future replacement.
 
Thank you again.
One more question(!), the Dalbani site has another product-KSL2130ccm, this looks very much like the entire transport mechanism, including the drawer etc which looks very much like the one in my player. Try as I might, I cannot find out what the laser pickup is in this part number(KSL2130ccm), and would like very much to find out if it is the same as the one in the Rotel(ie KSM213ccm and KSS213c)-for 2 reasons:1. Minimum purchase is $20.00, 2. would'nt mind replacing the whole bang shoot, cos the original has been butchered!
Again, I appreciate your help!
 
I've got the same machine and have replaced the laser once before. The symptoms were very similar with skipping and didn't play certain tracks. Changed it with a new one and it works flawlessly todate. I'm lucky to obtain the complete carraige and head as a whole assembly. No need to intricately dismantle the head from its carraige. Whole assembly is boxed as KSM-213CCM
If a replacement mechanism is new, its been factory calibrated and no further adjustment is necessary, only meant for a straight forward replacement of the old one. Do exercise extreme care when removing or re-installing the ribbon cable at mechanism to main PCB.
 

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Thanks- I got the same part ksm213ccm
I wish I were able to say this fixed it. Unfortunately it seems as though the laser is not "firing up" now. The mechanism moved to most inner position, lens bobs up and down, and announces 'No disc". I cannot see any red an assume either it does not work or there is some thing amiss- The connection to pcb may be suspect?
 
HCB said:
Thanks- I got the same part ksm213ccm
I wish I were able to say this fixed it. Unfortunately it seems as though the laser is not "firing up" now. The mechanism moved to most inner position, lens bobs up and down, and announces 'No disc". I cannot see any red an assume either it does not work or there is some thing amiss- The connection to pcb may be suspect?

Hi HCB,

The bad news is you'll have to remove the mechanism out again.
The god news is nothing's wrong - just remove the solder blob from the laser pick-up PCB.

Boky
 

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Thanks for all input. I lost patience and sent it off for repair to someone I found who can do these things much better than I can! Anyhow, turns out that the motor drive ic was faulty , replaced, general tidy up, and hey presto back to normal. I learned plenty from this exercise!
 
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