Hi, i own a D-105U for now almost 20 years. short story it died on my like 10 years ago, no play anymore.
i recently replaced the laser assembly from a known good source, and managed to found back my original copy of the service manual (not a reprint but a real one from Alpine directly). it played right away withtout any adjustments but is far from correct/stable.
i am not able to understand the whole procedure in step #3 altough i am extremely experiemented in this, there seems to be error in the manual there, and also it refers to a "jig" for the two final steps of adjustments...no details can be found about it.
Anyone with experience on this model? the procedure seems very "short" and uncomplete. i am used to far more complex and extensive procedures for cd players....
to the best i was able to perform, the CD now plays, but eventualy skips from song 1 to 4th or so randomly and experience difficulties to catch tracks.
at least it plays....
maybe there is something else bad in the circuit not related to adjustements. i will check power supply/capacitors since they are 30 years old already... (1990)
any kind experienced help would be appreciated.
thanks
i recently replaced the laser assembly from a known good source, and managed to found back my original copy of the service manual (not a reprint but a real one from Alpine directly). it played right away withtout any adjustments but is far from correct/stable.
i am not able to understand the whole procedure in step #3 altough i am extremely experiemented in this, there seems to be error in the manual there, and also it refers to a "jig" for the two final steps of adjustments...no details can be found about it.
Anyone with experience on this model? the procedure seems very "short" and uncomplete. i am used to far more complex and extensive procedures for cd players....
to the best i was able to perform, the CD now plays, but eventualy skips from song 1 to 4th or so randomly and experience difficulties to catch tracks.
at least it plays....
maybe there is something else bad in the circuit not related to adjustements. i will check power supply/capacitors since they are 30 years old already... (1990)
any kind experienced help would be appreciated.
thanks
Attachments
fwiw TP4 is GFS output from processor and TP5 is +5v so...there is no way that i can measure anything there once shorted, my only guess is to measure at TP6...
You may have other issues, however for the Tracking Error Adjustment try this... look at the tracking error signal on the scope and wind the timebase down to a fairly slow speed.
Now do some track jumps going from tracks near the beginning of the disc to ones at the end and back again. Look at the waveform during these track jumps and adjust the preset to give a notionally centred waveform i.e. not with a shift above or below an imaginary centre line.
For tracking gain adjustment look at the tracking error waveform and look for a really low fundamental frequency to begin to appear as you increase the tracking gain. When you see that fundamental appear just back the control off slightly until it just disappears.
Focus gain can be increased to the point that you start hearing white noise from the pickup coils. Just back off a little from that point.
Also have a read at this:
Sony CDP790 and KSS240 Restoration Project
There are a couple of video files at the end of post #1 that show the adjustment (in the days before I used YouTube).
GFS is 'Guarded Frame Sync'
Now do some track jumps going from tracks near the beginning of the disc to ones at the end and back again. Look at the waveform during these track jumps and adjust the preset to give a notionally centred waveform i.e. not with a shift above or below an imaginary centre line.
For tracking gain adjustment look at the tracking error waveform and look for a really low fundamental frequency to begin to appear as you increase the tracking gain. When you see that fundamental appear just back the control off slightly until it just disappears.
Focus gain can be increased to the point that you start hearing white noise from the pickup coils. Just back off a little from that point.
Also have a read at this:
Sony CDP790 and KSS240 Restoration Project
There are a couple of video files at the end of post #1 that show the adjustment (in the days before I used YouTube).
GFS is 'Guarded Frame Sync'
for the purpose of the searches and archives...
what i have found so far
-all limit/position switches where resistives. like 500 ohm and higher when "on"...this cd player was left asside for maybe 15 years so no wonder what could go wrong there...
-sled motor seems to stick randomly. after many tests and measurements, i found out that the Sanked hybrid module is latching itself inside, on the sled motor output....maybe it is defective i dont know. signal gets in from processor but not out. and it gets freaking hot then,like if the two transistors turns on. A power cycle brings back the normal operation, sled returns home. No, the motor is not dc short. Will replace this module or try external transistors to test.
-most of the screws on the cd transport where loose. dont know why.
to be continued.
what i have found so far
-all limit/position switches where resistives. like 500 ohm and higher when "on"...this cd player was left asside for maybe 15 years so no wonder what could go wrong there...
-sled motor seems to stick randomly. after many tests and measurements, i found out that the Sanked hybrid module is latching itself inside, on the sled motor output....maybe it is defective i dont know. signal gets in from processor but not out. and it gets freaking hot then,like if the two transistors turns on. A power cycle brings back the normal operation, sled returns home. No, the motor is not dc short. Will replace this module or try external transistors to test.
-most of the screws on the cd transport where loose. dont know why.
to be continued.
i fixed all of the above and now it plays very decent near perfect
i am very happy as this cd players plays very nice.
only thing now is that near the end of every songs, on any CD, it start to miss/skip a bit...it doesnt jump...it goes like dadadadada
i didnt mastered the procedure you listed above, english is not my native language...dare to explain me more ?
i have a DSO mixed Agilent scope (analog with crt) and a tektronix (digital), signal generators and test discs (sony yeds, ALpine and Shefields Labs)
thanks for your helps.
i am very happy as this cd players plays very nice.
only thing now is that near the end of every songs, on any CD, it start to miss/skip a bit...it doesnt jump...it goes like dadadadada
i didnt mastered the procedure you listed above, english is not my native language...dare to explain me more ?
i have a DSO mixed Agilent scope (analog with crt) and a tektronix (digital), signal generators and test discs (sony yeds, ALpine and Shefields Labs)
thanks for your helps.
If you hear this noise as each tracks fades out and the new one begins then I would probably suspect something more like a poor quality eye pattern.
Looking at the RF with a good scope is the first thing to do. The test point should be marked in the manual and typically the amplitude is around 1.2 to 1.5 volts peak to peak.
Any of those test discs should be OK and the quality of signal should be very clear and not fuzzy or jittery. It should be as clear as this:
Looking at the RF with a good scope is the first thing to do. The test point should be marked in the manual and typically the amplitude is around 1.2 to 1.5 volts peak to peak.
Any of those test discs should be OK and the quality of signal should be very clear and not fuzzy or jittery. It should be as clear as this:
