I own one of the old timers - Sony CDP-S45 (Model 1997) - hope some of you would be able to recall.
Have used it extensively for about 9 years. But now the lens seems to have lost its strength.
Long bump up - may not be useful to the OP now, but just for future reference.
1. The laser head is the very widely available Sony KSS-213, so it can easily be repaired if it becomes weak.
2. The transport and tray are generally bulletproof.
3. The main design weakness is the power supply for the opamp negative rail (-9.8V), which is generated from a switched-capacitor charge pump using a Sanyo LA5601 LDO regulator (which also regulates the +ve rail voltage of 5.2V). C955 and C959 will generally dry out and their ESR will increase with age, and these may be replaced with low-ESR electrolytics. I used 220uF/50V Nichicon HD for C955 and 10uF/50V Nippon Chemi-con SME for C959 (lots of other choices are available). Also replace C301 (I used 220uF/25V Panasonic FM) as a matter of abundant precaution.
4. Audible sonics are limited by IC303, IC304 (LPF and buffer for L & R channels), IC305 (headphone buffer), C333 and C334 (DC blocking capacitors). I did the following upgrades:
C333, C334: Panasonic ECQ 4.7uF/63V film caps instead of the original 100uF/6.3V electrolytics. The significant difference in value has little impact on the bass response - it's driving a high-Z line load and an opamp input only. It's also possible to use a Wima MKS2XL 3.3uF/50V or similar, possibly bypassed with a 100nF Panasonic ECHU PPS capacitor.
IC303, IC304: AD8022 in place of the original JRC 4558. Lots of other choices are possible, but it helps to use opamps that have good low-rail and asymmetric rail performance, since the +ve rail is +5.2V only and the -ve rail is -9.8V. The negative rail also has limited current as well as switching ripple from the charge-pump, so it also helps to use opamps with good PSRR (say around 100 dB) and low quiescent current. LT1361 and several other opamps are also usable.
It may also help to replace the rail-to-ground bypass caps (100nF ceramic) near IC303 and 304 with higher-quality film caps. I used Panasonic ECHU 100nF/16V caps, and they barely fit at the SMD locations.
IC305: JRC 4580 in place of the JRC 2156 or similar opamp. Nothing fancy is required here, since it's a unity-gain buffer for the headphone output, but it helps to have reasonably good current drive for low-Z headphone loads. SSM2135, JRC4556, THS4031 and several other opamps are usable here, but the 4580 does the job well with a 50mA rated output current and has sufficient slew-rate as well as GBW.
It's possible to do another level of upgrades by using a separate I2S-input DAC module like an ES9023 Sabre DAC, and supply it an I2S digital signal (LRCK, WBCK, DATA and BCK are available for tapping from the main board), and send the unbuffered analog output of the ES9023 to the RCA outputs, but I didn't attempt this right now - the SQ is very good with just the opamp and capacitor upgrades mentioned above.
