Troubleshooting CD Players
- Thread starter dr*audio
- Start date
calavera68
Member
I will check the caps in the reset line, I have a scope but I wasn’t getting good readings on the points I thought were the ones you asked me to check. The unit is labeled 120v 60hz. I replaced the caps on the unit and it worked until I put it together, could it be possible that a cap failed? Thanks again for all the input, This is a hobby for me and I still have a lot to learn.
dr*audio
Fish fingers and custard!
1. You could have installed a cap backwards.
2. You could have a solder bridge or solder splash shorting something out.
3. You could have a crimped wire or installed the wrong screw in the wrong place (too long) and now it's shorting something out.
4. Sony is notorious for using the screws that hold the pc boards for completing the ground path. You could have left a screw off, or the screws are loose.
Circumpunct
New Member
Back on the Hitachi Opus 1 here from two pages ago. After much fun and games on the brown/black glue damaged power supply board, we now have all 5 voltages to the CD board restored. Problem now is after focusing and starting to spin the disc, the speed is erratic so TOC is never read. If i let it keep trying to settle down and read then the sled also moves outward a cm or so - bit quirky. I did replace the OPU three years ago when i knew nothing about cd repair. It probably didn't need replacing, but now i have a laser meter and it's putting out 0.26mW during the focusing phase, so possibly all is ok in that department.
There's no ripple on any of the 5 board voltages. I took out Q907 & Q906 - they are testing good for diodes and resistances. IC904 has correct voltages according to the schematic, but pins 1 to 4 are covered in the same glue - only this time less heat or time in operation thru its life has not turned the glue black. Looks a bit suspect though.
As for the spindle motor, just to recap the original symptom was: selecting the CD player function the disc motor would start spinning at maximum speed in a constant fashion, no variability to be seen. This was because the -10v rail was missing to one of the push/pull drive transistors. So it looks like the motor is ok at a guess.
Not sure where to go from here. Maybe replace IC904? Or maybe look further upstream first?
I would attach a section of the relevant schematic like you did if i knew how to do it!
I tried - came out all fuzzy. Apologies.
There's no ripple on any of the 5 board voltages. I took out Q907 & Q906 - they are testing good for diodes and resistances. IC904 has correct voltages according to the schematic, but pins 1 to 4 are covered in the same glue - only this time less heat or time in operation thru its life has not turned the glue black. Looks a bit suspect though.
As for the spindle motor, just to recap the original symptom was: selecting the CD player function the disc motor would start spinning at maximum speed in a constant fashion, no variability to be seen. This was because the -10v rail was missing to one of the push/pull drive transistors. So it looks like the motor is ok at a guess.
Not sure where to go from here. Maybe replace IC904? Or maybe look further upstream first?
I would attach a section of the relevant schematic like you did if i knew how to do it!
I tried - came out all fuzzy. Apologies.
dr*audio
Fish fingers and custard!
I think the first thing to do here is look at the RF test point with your scope, adjust the horizontal sweep so you can clearly see the eye pattern, which won't be stable since the speed is varying, but verify that the waveform is there and 1.5V p-p. Did you mess with any of the adjustments? Did this ever work?
Circumpunct
New Member
The system came to me as broken (as described) from a friend, so never had the laser be seen to be operating. Back 3 years ago before i replaced the OPU, i did some slight twiddling of R905, the laser diode o/p, but reset it and then installed the new pickup. I still have the old OPU...getting tempted to refit it.
So Q901 voltages are ok. Tracking and focus offset have been minorly tweaked to the spec on page 11.
The eye pattern is unclear and seriously jittery. Amplitude varies continuously from about 1.1v to 1.5v which the manual says are all acceptable figures (if stable of course).
I experimented a bit with all three pots for o/p, focus and tracking, being careful, before setting them to spec. One thing i've noticed now (since the tweaks) is that when i hit the interlock switches to engage start-up, the laser while focusing up & down, soon starts travelling outwards to the very edge of the disc, not just moving a cm out as before. When it gets to the edge the rf pattern disappears from my scope and the disc speed increases to a stable velocity.
dr*audio
Fish fingers and custard!
Try this:
Monitoring rf signal with the scope, adjust focus offset and tracking offset for max waveform. If that doesn't fix it we have to look at the Servo circuit.
calavera68
Member
Back to Sony CDP-X555ES
I double checked caps and all are installed correctly per the schematic and pcb markings. I checked for any solder bridge or splash that could be shorting something out and everything looks ok. I checked continuity from ground posts/leads to chassis and it is OK. All screws tighten and in right place. I took some voltage readings at points in the reset line which are here:
c925 = 4.98v
c921 = 4.98v
4.98v - r905 - 3.86v
3.86v - r906 - 3.63v
3.63v - r907 - 2.07v
C924 = 3.86v
3.86v - d906 - 10.02v
C923 = 10.02v
VRST = 10v
I am attaching the section of the schematic where the readings were taken. I will be traveling for work for the next 4 weeks, I may have to continue troubleshooting then. Thanks again for your help, I appreciate it.
I used a couple of capacitors rated for higher voltage and same capacitance in a couple of places since I was out of the same voltage, I believe this should be OK, correct me if I am wrong.
I double checked caps and all are installed correctly per the schematic and pcb markings. I checked for any solder bridge or splash that could be shorting something out and everything looks ok. I checked continuity from ground posts/leads to chassis and it is OK. All screws tighten and in right place. I took some voltage readings at points in the reset line which are here:
c925 = 4.98v
c921 = 4.98v
4.98v - r905 - 3.86v
3.86v - r906 - 3.63v
3.63v - r907 - 2.07v
C924 = 3.86v
3.86v - d906 - 10.02v
C923 = 10.02v
VRST = 10v
I am attaching the section of the schematic where the readings were taken. I will be traveling for work for the next 4 weeks, I may have to continue troubleshooting then. Thanks again for your help, I appreciate it.
I used a couple of capacitors rated for higher voltage and same capacitance in a couple of places since I was out of the same voltage, I believe this should be OK, correct me if I am wrong.
Attachments
Circumpunct
New Member
That was tricky as the waveform's going up and down and concertina like a squeezebox...plus the adjustors are under the spinning disc. Anyway no luck i'm afraid.
I wonder if the formerly missing -10v & -5v rails did some harm to the servo circuit. New territory now, but all ears. Thank you
dr*audio
Fish fingers and custard!
Measure the voltage on all pins of IC903.
dr*audio
Fish fingers and custard!
I was wrong, the disc motor speed is controlled by IC906, the Digital Signal IC. Here's the block diagram:
Here's the pinout and pin description for IC906:
So a servo control system requires a reference clock, which is in this case VCO1 on pin 9, and then the EFMs signal ( Think that may stand for EFM Synch, derived from the RF signal) which it is going to synch to the reference clock by changing the speed of the disc motor. So if it doesn't have a good reference clock or the EFM signal is noisy or low, it can't stabilize the disc speed.
EFMS comes from the preamp IC901 pin 16. It is probably going to be easier to see there with your scope probe but you may have to solder a thin wire to the pin. You should see a healthy peak to peak signal of at least 1V, but I am thinking it will be 5V. Verify that it is there and strong. It will vary because the speed is varying.
Next look at VCO1 on IC906 Pin 9.
I think this varies with the motor speed. You should see a healthy signal here, at least 1V p-p. You can probe it at C931.
Next look at PDO, pin 11 of IC906. You can probe it at R971. This is the control voltage for the VCO1 and it should be varying around all over the place because the motor speed is changing. If it's constant, IC906 is probably bad. Look at IC903 pin 1, it should be similar but higher voltage.
CX23035 is in stock at B&D but it's so expensive I would be hesitant to order one in case it isn't bad, but I am thinking it might be.
https://www.bdent.com/cx23035.html
Attachments
Circumpunct
New Member
Thanks Doc, The results according to my death-o-scope:
IC901 pin 16. about 4v p-p, an eye pattern with the eyes gouged out (see pic) I wouldn't call it healthy.
VCO1 4v p-p strong & clear with no motor running. With motor, slightly less voltage and a bit fuzzy. Freq seems ok.
PDO 2.5v dc with no motor running.
With motor...here's the pic
D.C. coupling used. Varying in amplitude (the pk-pk noise) but steady 2.5v centre beam, and varying on the x-axis concertina fashion.
IC903 pin1 is hard to measure. Whole area has a glued shield over it. I did measure it from below yesterday with the whole assembly vertical, but not with the motor running in that position. -164mV for what it's worth.
CX23035 would be a challenge to solder in. I'd have to practise on something else. Still hoping it's an easy dodgy capacitor..
calavera68
Member
pin1=4.98v
pin2= -4.3mv
pin3= 3.62v
pin4=73.5mv
pin5=73.4mv
pin6=2.06v
pin7=-5mv
pin8=4.95v
pin9=-5mv
pin10=4.95v
pin11=-5mv
pin12=4.96v
pin13=-5mv
pin14=4.97v
dr*audio
Fish fingers and custard!
Sounds like the IC is bad. It's an inverter so with pin 5 low, pin 6 should be at 5V.
It is also possible that something is loading it down.
1. Try carefully de-soldering pin 6 and then see what the voltage is on pin 6.
2. If Pin 6 is still 2V, look at it with a scope to make sure it's a DC voltage and not a waveform.
3. If Pin 6 goes up to 5V when it's desoldered, Turn the unit off and measure the resistance from pin 6 pad to ground.
dr*audio
Fish fingers and custard!
We need to get a good look at what IC903 pin 1. You could get it at R965, R964 or D913. Solder a test wire in if you have to. Look at it with the scope. It should be doing the same thing that PDO is doing but higher amplitude.
Circumpunct
New Member
Keep forgetting wire soldering is our friend.
Pin 1 without motor:
~0.6v p-p
Pin 1 with motor:
Nothing like PDO.
Last edited:
dr*audio
Fish fingers and custard!
Also IC903 should have a gain of 4 so that low level you are seeing is a further indication of a bad opamp. You can use a NE5532, or pretty much any opamp that is internally compensated.
Circumpunct
New Member
Thanks! The old one's out. My first chip failure - looking between the plastic halves it looks a bit messy on the ends. Can they 'leak' a bit with lots of heat over time? I went for the exact replacement. Should be here Monday latest - will let you know.
