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-   -   Krell KAV-250CD Transport Issues (http://www.diyaudio.com/forums/digital-source/215500-krell-kav-250cd-transport-issues.html)

PentAmateur 2nd July 2012 04:40 PM

Krell KAV-250CD Transport Issues
 
I have had a Krell KAV-250CD player (coupled with a KAVP/A combination) for nearly 14years. In that time I have had a few problems with the player reading certain discs, either not finding the TOC or not being able to play the disc even after the TOC has been located. It has never been able to read copies. Over the past few months this seems to have got worse. Having scanned the web I think it must be a Mk1 unit; I'm not sure about the transport mechanism but it certainly has a Sanyo SF P1 laser head.

I'm wondering whether it is possible to replace the mechansm with something a little more reliable/robust. Does anyone have any advice or experience of this? I does look as though its a fairly common problem with this unit. I'd prefer not to have to replace the whole unit if at all possible.

Any advice would be greatly appreciated

tiefbassuebertr 3rd July 2012 12:58 PM

check out this threads:
http://www.diyaudio.com/forums/digit...ain-board.html
http://www.diyaudio.com/forums/digit...al-wanted.html
because the same CEC-Sanyo parts are also in use in the listed models there, maybe you will find by this model numbers the right informations.

PentAmateur 4th July 2012 08:40 AM

Many thanks tiefbassuebertr,

I saw these the other day but will follow up more closely. If anyone has specific experience of changing the mechanism in the Krell, I'd love to hear about it.

seppstefano 5th July 2012 12:19 AM

IMHO,
before thinking of exchanging the transport you could try cleaning the lens with a specific product for eye-glasses and/or replacing or beefing up the caps in the psu.

My 0,02

Stefano

stephensank 6th July 2012 05:36 AM

The SF-P1 is one of the most reliable lasers ever made for cd. Your problems are almost 100% certainly due to tracking drive mech or alignment issues. Most common with these is broken teeth on drive gears, but could be just a lubrication problem, if it's not simply misalignment of servos, laser power, etc.

tiefbassuebertr 6th July 2012 09:24 AM

4 Attachment(s)
Quote:

Originally Posted by stephensank (Post 3083147)
The SF-P1 is one of the most reliable lasers ever made for cd. Your problems are almost 100% certainly due to tracking drive mech or alignment issues. Most common with these is broken teeth on drive gears, but could be just a lubrication problem, if it's not simply misalignment of servos, laser power, etc.

I agree.
The best solution for troubleshooting is the purchase of a used CEC2100 or CEC3100 (CD2100, CD3100).
By exchange and cross-comparison of the loader, optical pick-up and main-PCB you will find quickly the main reason for the observed unwanted effects.

check also the attachments and this URLs:
https://sites.google.com/a/lvsystem....grage-cec-2100
so as post #19 about
http://www.diyaudio.com/forums/digit...n-board-2.html
for the adjustment hints.

PentAmateur 7th July 2012 12:35 PM

Thanks for the replies. Having played with the unit for the past few days, including thorough clean of the lens, rails etc. I'm convinced it is a tracking problem. Using a little 'gentle force' I can get the unit to pick up some of my troublesome disks but as yet have not worked out a way to adjust the tracking. All the gears/teeth etc. look fine.

stephensank 7th July 2012 09:36 PM

That confirms absolutely that it is not a laser problem. Have you lubricated the laser sled guide rails? The way to test for a lub issue is to remove the one of the tracking drive gears to allow the laser to move freely. If you feel any resistance when manually sliding the sled back & forth, you just need to lub. You should use a fairly thin silicone grease, properly, but can get away with a light petro-based grease, which you can also apply to the shafts of the driver gears. You should NOT change any adjustment trimpots on the boards without knowing exactly what you're doing, and it is extremely rare for an SF-P1 to drift to where it should need any such adjustments in any case.


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