Hello everybody, I recently bought a Sony-D50 which I hooked up, what happens is when I put in a CD, it turns on, spins for about 3 seconds, and then it shuts off, the lens does try to focus by going up and down, but does not detect it unfortunately, I have read on a few other topics that you are supposed to see a red light coming from the laser, but I don't see that with mine, I know you are not supposed to look directly into the lens, but when I use my phone camera, I cannot see the so called red light, I did open the unit but didn't see anything out of the ordinary, I tried looking at the mechanism but unfortunately I couldn't flip the board up, because of the flat ribbon cable that is soldered on there, and I don't have a soldering iron that is suitable for desoldering that cable, does anybody know what I can investigate or look at further because I think this one deserves a revival! Thank you for reading this thread, and greetings from Holland!
Please note the D-50 has 2 different switches that need to be closed: an open/close switch (S902) and a laser on switch (S901). If S901 is not closed (it's a hole in which a door pin goes into) the laser will not turn on. On thing that I recommend checking are the rubber dampers on which the mechanism sits as these tend to turn into plastic and break. I got a D-50 in this situation in which parts of the broken dampers got into the sled gears and broke some teeth, which unfortunately deemed the unit a no fix. These can also get inside the optical pickup block. Another point of potential failure on these is the DC-DC converter, so check the voltages there. Note the unit needs to be on for output voltages to be present as the DC-DC has a power on signal coming from the main CPU.
Thank you for the reply, when I received the unit, I took a close look at the DC-Input and saw a discoloration, I suspected that the previous owner used an adapter with the wrong polarity and 'POP' so I suspect the DC-DC converter is probably fried, which I feared the most, but I will try to test it anyway, I don't know what the markings are on the chip, and which voltages are to be expected at which pin, does anybody know that?
The voltages of the DC-DC converter are labeled on the PCB silkscreen as far as I remember, at least in some versions. For a clear reference, go to page 37 of the service manual and you have all the voltages clearly labeled with corresponding pins in the bottom right corner of the schematic. Service manual here: https://elektrotanya.com/sony_d-5_d-50_cd_player.pdf/download.html There are 3 main voltage rails that it needs to output: a 2.2V reference voltage and a +/-5V, apart from the 9V which is simply passed through the internal PNP transistor once the DC-DC is on.
Thanks, I have tried to understand the service manual as much as possible and I think I got the hang of it, I measured the 9v at the barrel jack input on the PCB, and I got a nice 9.13v, the next stop is the transistor, I measured the voltage on pin 2 and got 9.13v (where 9v is expected) and when I measured pin 3 (where 5v is expected) I got 8.64v! I do have to note that the player was not "playing", it was simply in standby mode (green switch on) but could this possibly mean that the transistor is fried and has to be replaced?
You are reffering to IC802 ? That's a 5V voltage regulator, not a transistor. The fact you have 9.13V at the DC in jack but only 8.63V at the input of voltage regulator means the regulator is loading down the power supply, likely due to an internal short circuit. I remember reading on tapeheads this was a common failure, they were calling this a "reset chip", probably due to the fact diode D802 and capacitor C803 (which are at the input) are generating the reset signal for the main CPU. IC802 can be replaced with the generic LM7805 type regulator (TO-220 package) or LM78L05 type (TO-92 package - 100mA current handling capability). Can't find a datasheet for the original S81250HG, but most likely 100mA is enough for this application. The newer ones have protection circuits built-in, so there isn't any risk. Pay careful attention to the pinout, as the 7805/78L05 have a different pinout than the original.
Yes, I meant IC802, thanks for the conformation, I think I will order a replacement, but I am very sceptical that it will work after replacing it, as I did try the unit of course with the defective IC802 passing through 8.64v (where 5v is expected) which in turn probably caused harm to all of the components/IC's in that chain, that expected 5v but got 8.64v instead from pin 3 of IC802, so there might be a lot more dead components
Just realised I misread your previous post and you stated the regulator was outputting 8.64V. Worth trying to replace the regulator anyway, I recommend using the newer 7805 one as it has all the protections built-in and its overall better than the original S81250HG. Also, the replacement S81250HG found on Aliexpress is likely not genuine, so yet another reason to go for the 7805 instead. These you can find locally at electronic components stores if you have any in your area.
