Dear diyAudio
Greetings! Long time lurker, first time poster.
Background:
Previous owner said it cannot read disc, and said even the disk is not spinning. Upon receipt, I proceeded to clean the lens, lube the spindle motor and also the sled rails (sewing machine oil - I dabbed some onto a cotton bud, and then wiped it on the rails). Laser assembly is KSS-210. Plugged everything in and started it up with a CD (~41 mins, early 90s, John Lee Hooker). The CD spins, but it took a long time (~60s) to read the TOC. Once TOC is up, I played track 1. It plays, but with a fair bit of distortion (like dirty vinyl?). It also mistracks somewhat, and finally gave up (back to TOC) at the 2min mark.
2. I then pulled out all the ribbon connectors from transport to board, cleaned the contacts and reconnect. At this point, the lens did not hunt (and hence, no spinning of disk). Stumped, I tightened all the ribbon connections and now it does read the TOC and plays. [ribbon / connectors faulty, cold solder?]
I noticed the playing is smoother, albeit with 1-2s skips, and I can get it to select all the tracks in the CD (all 20). Interestingly, the longer I allow it to run, the distortion seems to get lesser. It did refuse to recognize longer CDs (>60 mins). Newer, louder CDs (post-2000) under 60 mins can be recognized, but the distortion was so harsh it was unlistenable. It sounds like it was clipping?
3. On close inspection of the board, C503 and C504 are bulging. C208 and C209 are suspect too.
At this point, what would be my next course of action?
1. Change out the suspect caps?
2. I have a scope, so attempt tracking / focus adjustment?
Attached is the service manual, and a couple of videos to demonstrate the sound quality in a downloadable link. https://fileport.io/9XpST5wy4bhp
Thank you!
Greetings! Long time lurker, first time poster.
Background:
Previous owner said it cannot read disc, and said even the disk is not spinning. Upon receipt, I proceeded to clean the lens, lube the spindle motor and also the sled rails (sewing machine oil - I dabbed some onto a cotton bud, and then wiped it on the rails). Laser assembly is KSS-210. Plugged everything in and started it up with a CD (~41 mins, early 90s, John Lee Hooker). The CD spins, but it took a long time (~60s) to read the TOC. Once TOC is up, I played track 1. It plays, but with a fair bit of distortion (like dirty vinyl?). It also mistracks somewhat, and finally gave up (back to TOC) at the 2min mark.
2. I then pulled out all the ribbon connectors from transport to board, cleaned the contacts and reconnect. At this point, the lens did not hunt (and hence, no spinning of disk). Stumped, I tightened all the ribbon connections and now it does read the TOC and plays. [ribbon / connectors faulty, cold solder?]
I noticed the playing is smoother, albeit with 1-2s skips, and I can get it to select all the tracks in the CD (all 20). Interestingly, the longer I allow it to run, the distortion seems to get lesser. It did refuse to recognize longer CDs (>60 mins). Newer, louder CDs (post-2000) under 60 mins can be recognized, but the distortion was so harsh it was unlistenable. It sounds like it was clipping?
3. On close inspection of the board, C503 and C504 are bulging. C208 and C209 are suspect too.
At this point, what would be my next course of action?
1. Change out the suspect caps?
2. I have a scope, so attempt tracking / focus adjustment?
Attached is the service manual, and a couple of videos to demonstrate the sound quality in a downloadable link. https://fileport.io/9XpST5wy4bhp
Thank you!
Update:
So the caps to replace the bulging / leaky ones finally arrived and I swapped them out. Caps replaced were near the PSU, a pair is near the DAC. 2200uf, 1000uf, 470uf at the PSU side, 330uf near the DAC.
There is some minor improvement in the sense it spins up and read the TOC for maybe 75% of my CD collection (as compared to half earlier). However, half of those which can be read can variable distortion when played back,, ranging from mild static in the background, to all out clipping / buzzy levels. Track selection, track seeking works fine. On the CDs which it reads and plays fine with no other issues. It spins ALL discs, so at least the laser reading stage reaches Focus OK?
I have tried using a scope to get the RF pattern, with AC coupled, 0.2 mV / div and 500ns / div but always end up with a dynamic waveform (as opposed to a static eye pattern). I enabled persistence (infinite) -which is the only other option, compared to off - and got a smeared, bleary-ish almost eye-pattern which is overlaid still by the dynamic waveform. I think I am probably missing something with regards to the scope settings.
Hence, what would be the suggested next step?
a. Change the laser head ?
b. Swap the capacitors at the servo section / digital / analog output?
Thanks for your thoughts and comments.
So the caps to replace the bulging / leaky ones finally arrived and I swapped them out. Caps replaced were near the PSU, a pair is near the DAC. 2200uf, 1000uf, 470uf at the PSU side, 330uf near the DAC.
There is some minor improvement in the sense it spins up and read the TOC for maybe 75% of my CD collection (as compared to half earlier). However, half of those which can be read can variable distortion when played back,, ranging from mild static in the background, to all out clipping / buzzy levels. Track selection, track seeking works fine. On the CDs which it reads and plays fine with no other issues. It spins ALL discs, so at least the laser reading stage reaches Focus OK?
I have tried using a scope to get the RF pattern, with AC coupled, 0.2 mV / div and 500ns / div but always end up with a dynamic waveform (as opposed to a static eye pattern). I enabled persistence (infinite) -which is the only other option, compared to off - and got a smeared, bleary-ish almost eye-pattern which is overlaid still by the dynamic waveform. I think I am probably missing something with regards to the scope settings.
Hence, what would be the suggested next step?
a. Change the laser head ?
b. Swap the capacitors at the servo section / digital / analog output?
Thanks for your thoughts and comments.