Seiko pcdp

hexisracing

Hi
Last year I sent my seiko to you for repair, and you didn't fix the problem that I said, the phone output is getting weaker little by little, and now I would like to fix it by myself, except for replacing the amp, do you have other suggestions to fix this problem?  or do you have the service manual of seiko pcdp

kaosun

How are you Hoping?
Last time I focused on your reading issue so I guess it still has a perfect reading capability. I did test the audio but didn't find anything wrong. To handle this issue, pls test your line out to see whether you had same issue weaker and weaker? I'll post later what to do here. Thx!

hexisracing

Oh , by the way I also had tested lineout with sony x88 speaker, and the sound was normal, nothing else

hexisracing

And also, some of the cd will cause phone output more weaker, either cd or cd-r, first time I thought if it is the laser's problem, because some of cds may cause laser needs more power consuming, and then that was , I switched the laser lens' power variable resistor to smaller, and the sound was better. However, still some of cds cause phone output getting weaker.

hexisracing

But if you minimize the volume, and remain for few seconds, then switch back, the sound will become better again

hexisracing

Or if you play for few minutes, the sound will not weaker anymore unless you turn it off and restart it, I think if it is the build-in step-up adapter needs replacement?

kaosun

I've never encountered the earphone weaker and weaker issue is caused by laser. Let's focus on one single CD. Say the CD has normal output via Line Out while has issue via earphone.

Since the Line Out is normal, the audio generated by DAC should be fine. The route for the audio derives from DAC, then enter audio Low Pass Filter(LPF), goes out via Line Out jack. Also, the audio goes from LPF output to audio VR to adjust volume. Then the audio amplifier which is BA3570F will amplify the audio and output it to drive earphones. The BA3570 has external DBBS switch to choose bass off/1/2.

If you have single channel issue, pls check corresponding channel's external components. If you have both channel simultaneously issue, pls check components for sharing like power/reference power filter capacitors/resistors.

I attached the PDF file for the BA3570 for your reference. If you'd like to take a look of the whole schematic diagram, pls refer to SONY D33. D33 is a good example which has more than 80% identical with your SEIKO.

hexisracing

also I found that the right side channel of the sound will fade out, is that easy to fix

kaosun

hexisracing 2016-03-17 18:26
also I found that the right side channel of the sound will fade out, is that easy to fix

Pls try line out to see whether line out has same issue.
If line out is OK, then the issue is caused by earphone amplifier. Then it's better to have the chip replaced and try. Also, pls try DBBS I/II/III to see which level causes fading.