I have this CD player with strong distortion on both channels like white noise, even with a silent audio track. The player worked perfectly until it was connected to amplifier that I had never tried before 😞. This makes me think of a problem with the analog output or from the DAC onwards, the tracks are read and can be heard. The service manual is easily found online. I started to probe the power supply voltages and apart from slight deviations they seem ok, I have a USB digital oscilloscope available that does not show me the RF signal with an eye pattern. It seems to me that there is a DC component in the output. In short, lots of ideas but confused, can someone give me a hand?
You may have damaged ground traces or broken connections on the RCA jacks. A DC component suggests damaged muting transistors, or you lost one rail of the op amp supply.
To see an eye pattern, you want an analogue oscilloscope that can sweep 0.5 us/div with 0.5 V/div vertical sensitivity (not normally a problem). So 20 MHz older scopes to maybe a 10 MHz newer analogue scope as a minimum. To use a DSO, well ... have fun. Mine is $25K and presents a useable eye pattern. Less expensive scopes when I bought mine a couple years ago were useless.
To see an eye pattern, you want an analogue oscilloscope that can sweep 0.5 us/div with 0.5 V/div vertical sensitivity (not normally a problem). So 20 MHz older scopes to maybe a 10 MHz newer analogue scope as a minimum. To use a DSO, well ... have fun. Mine is $25K and presents a useable eye pattern. Less expensive scopes when I bought mine a couple years ago were useless.
Does it work OK if moved back to original amp? If so it is probably oscillation due to too much capacitive load from the new amp... Oscillation well above 20kHz will be heard as noise and distortion in the audio band.
Unfortunaly it has same problem on other amps, headphone output is distorted too. Playing a swipe audio track seems that distorsion grow up with frequency.
Like anatech said I chechek op amp supply and are ok. I found more volts then schematics values on emphasis transistors (q401, q451) emitter and collector, 10 time more, giunctions seem ok. For semplicity I attach analog output scheme
Like anatech said I chechek op amp supply and are ok. I found more volts then schematics values on emphasis transistors (q401, q451) emitter and collector, 10 time more, giunctions seem ok. For semplicity I attach analog output scheme
Pull Q402 and Q452 (muting, 2SC3622A). Try it again. Note that you may get popping and other system noises without the muting function. Disconnecting the collectors would suffice.
If you need to replace them, muting transistors typically have a very large emitter-base breakdown voltage. They are special transistors. I have not checked these specs, but the 2SC2878 was another designed for muting. Yeah, checking shows you have a 15 volt reverse breakdown rating. Normal transistors are 6 ~ 7 volt.
If you need to replace them, muting transistors typically have a very large emitter-base breakdown voltage. They are special transistors. I have not checked these specs, but the 2SC2878 was another designed for muting. Yeah, checking shows you have a 15 volt reverse breakdown rating. Normal transistors are 6 ~ 7 volt.
If the player has a digital output and you have an external dac or amp with digital in, you can use this to verify that the problem is not in the digital part of the player. Bad ram chips can give weird symptoms.
Have you checked what all the opamp output voltages are? Do they seem to correspond with the diagram or not?
The diagram in the manual should say what conditions the voltages are measured under such as play, stop, pause etc.
Does this player use a separate DRAM memory chip as that can can cause constant noise and distortion. That's more a Philips problem but its worth checking if this one uses such a chip.
The diagram in the manual should say what conditions the voltages are measured under such as play, stop, pause etc.
No output (and assuming the DAC is compatible) suggests an issue much further toward the front end.
Does this player use a separate DRAM memory chip as that can can cause constant noise and distortion. That's more a Philips problem but its worth checking if this one uses such a chip.