A D55t Repair Recording
A SONY D55t was sent here for repair. The issues are no response, not reading but LCD responses.The LCD reponses to the keyboard means CPU and its power supply is working. The special parts for D55t are DC-DC switching power box and KSS110C laser. Measurement indicates that the power box lacks of +5V output.
Thank you! Now it's not so difficult to adjust laser. Measurement confirmed that the 2SA1241 has broken. It was replaced by a 2SB1308 which has similiar parameters, 20V3A5W.
Now the D55t works. I connected an oscilloscope to check its RF eye pattern. The RF signal has good amplitude but a little vague. The laser keeps reading but seldom reads out. If a laser diode has aged, the output power will decrease, so the RF amplitude should be smaller. But the amplitude is good enough....If the PDIC has aged? The six diodes are isolated inside of the translucent plastic... It's less likely to be aged.. I'm confused if everything is good, is it possible that the motherboard or RF amp part has certain issue?
I checked the external components one by one but each one is pretty good.... So I have no idea but comparing the optical element with a working one.
The reflecting light is purple in working laser; however, the one in non-working one is yellow!
Comparision indicates that the optical elements in non-working laser has aged. The further investigation confirmed the coating on the surface of each element is aged; therefore, the coating helped laser going through the elements doesn't work any more.
Hence, I replaced the optical elements adnd by the way the laser diode which is a SHARP LT022MC, it also used in PHILIPS CDM2 lasers.
After precise PDIC alignment, the RF pattern has been adjusted.
So far, the D55t has been saved its life to read discs but both channels are full of distorted music. The measurement indicates that the issue is caused by audio board although I replace its DAC PCM55 but nothing happened. NO idea but handled this issue by replacing the audio DSP/DAC board. Now the audio is perfect.
However, the R channel has no sound. Later the test indicates the r channel volume resistor is broken. After repair, the VR still doesn't work well, so it's replaced by a identical one. Then, test confirmed everything works fine!
老顾牛逼了，可以换激光管了，可惜你不在天朝，我的D-T55继续压箱底中:lol
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