Luxman D-105 Sled won't park.
An oldie but a goodie from 1989. It is basically a Sony CD player with tube outputs. It plays discs fine with no skipping. If the
stop button is pushed anywhere from imediately after play is pushed,to half way through a disc,the sled drive moves back towards the parking position and does not stop. The sled drive worm wheel clicks against the optics rack gear a few times and then stops. The position sense switch closes properly when the rack gear hits it and that is seen happening on pin 22 of the CXA1082BS servo chip. If pin 22 is shorted right to ground after stop is pushed,it acts the same way so it is not the switch.(This IC also provides the sled drive output on pin 20) Interestingly enough,if the disc is allowed to play more than half way through or it is advanced past 1/2 way,stop is pushed and it finds the correct parking position without overdriving. Looking at the non-inverse and inverse inputs pins 19 & 21,they are the normal. This servo chip was replaced with no fix. The only other thing I saw was that the Sense input on pin 24 was going to a positive dc level only for the duration of the sled overdrive. This pin outputs FZC,AS,TZP,SSTOP(the limit switch on/off signal detection pin for disc inner periphery detection) and 'Busy Through Command From CPU'. This sense output goes to pin 37 on the main micro and pin 18 of the CXD1135QZ Dig Control IC. Pin 18 of this IC shows that this sense signal is an output from this IC. It uses data from the micro as inputs on pins 13,14,15 which are 'busy' during the overdrive event. As soon as the data stops on these pins,the sled stops driving. This IC also uses an input on pin 17 from the CXA1082BS called CNIN. It is input to pin17 where it goes to a portion labeled Tracking Counter and then onto the CPU Interface block which is the same as previously mentioned,pins 13,14,15,and Sense output,pin 18. Sure seems like a glitch in the data but after going round on this, I can't isolate why this data stream is active and driving the sled too far. These were really rare units and we only sold 2 or three of them so I don't hope for much of a response from this but hey.A man can try. Thanks for taking a look.