Strange phenomenon... with the laser DISconnected, the sled motor keeps going (not even stopping when closing the leaf switch), but with the laser connected, it doesnt move at all (not a mechanical blockage, this behavior is also present with the laser/wheel disengaged)...
Hi studiostevus,
When you set the machine up in a non-standard configuration, don't expect normal behavior. I've worked on tons of these machines but have never once did what you did, so I can't even begin to explain it.
When you disconnected the head, did you short the laser diode?
When you set the machine up in a non-standard configuration, don't expect normal behavior. I've worked on tons of these machines but have never once did what you did, so I can't even begin to explain it.
When you disconnected the head, did you short the laser diode?
It's not the laser... I switched out the laser from the working unit to the non-working unit (solder blob and all), same story. Also switched out the entire drive mechanism. No change.
So then the behavior under a standard configuration is that the spindle is speeding up faster and faster. The sled is stuck in the same position (unless the laser gets disconnected).
So then the behavior under a standard configuration is that the spindle is speeding up faster and faster. The sled is stuck in the same position (unless the laser gets disconnected).
The spindle speeds faster because there is no data to lock to. The servo hasn't got a signal. Why?
You absolutely do require an oscilloscope, analogue. Period.
You absolutely do require an oscilloscope, analogue. Period.
Poked around a bit last night on the Servo and DSP:
- EFM signal (coming from RF amp into the DSP) I can't determine whether it's ok or not, but the circuit description says that the DSP will derive 2 clocks (8.64Mhz and 4.2Mhsz from EFM) and both of these derived clock signals are visible and ok. Assuming then that EFM is fine? It's 4VDC with a sawtooth over it.
- Between the DSP and the Servo there should be some PLL going on which drives the disc motor servo, and both the incoming and outgoing signals seem ok.
- VCO (DSP output, servo input) - 2-3V sawtooth - ok
- VCI (DSP input, servo output) - 2-5V sawtooth - ok
- PDO (phase difference compensation) - 5VDC - ok?
- The motor steering from the DSP to the Servo does not seem to be ok
- FSW "output to change the time-constant of CLV LPF in Servo - 0V, no signal
- MON "Motor on/off control output" - 0V, no signal
- MDP "Motor drive output. Speed control pulse in servo or PLL mode" - 0V, no signal
- MDS "Disc motor drive output. Speed control pulse in PLL mode" - 4V. Conclude then that the player is in PLL mode and the DSP is telling the servo to speed up? But why, if the PLL signals are working fine it should not tell the servo to overspeed. And why does the player go into this mode without a disc loaded? Is the problem in the 'sense' signal between DSP/servo and the MPU not coming through, so the MPU instructs the DSP/servo to go faster and faster?
- Supply voltages and ground connections - ok
#1. Eye (RF) pattern. Look at amplitude and stability.
You do this before adjusting and changing anything. Do not adjust any controls, the machine used to work with the settings it had. Almost everyone messes with the trim pots first. You pretty much then guarantee you need a trained tech if you do that.
You do this before adjusting and changing anything. Do not adjust any controls, the machine used to work with the settings it had. Almost everyone messes with the trim pots first. You pretty much then guarantee you need a trained tech if you do that.
I received a new servo chip (CXA1082) and a new buffer for the sled motor (STA341). After replacing the old ones, unfortunately the problem is not fixed but symptoms have changed. They also have become a bit erratic.
Under a power-up condition with no CD loaded (same as with a CD loaded):
I checked the VCO, seems there is no PLL lock, at least I don't get a good signal irrespective of the VCO pot setting (procedure as per service manual).
From the erratic behaviors I suspected bad soldering and resoldered all IC connections. Also used freeze spray. No difference.
I see the laser moving up upon power up, but nothing more than that. There is no current flowing (same as before), and no red light. I guess the player doesnt run through its startup routine enough to power up the laser.
Under a power-up condition with no CD loaded (same as with a CD loaded):
- Sled motor moves to most outwards position, STA341 gets very hot, and voltages supplied drop to +8V and -11V (should be +/-11V). It has this behavior with both the old and the new STA341, so I assume the STA341 is not at fault but it's something higher up the chain.
- Spindle spins backwards, sometimes at full speed for a minute or so. Sometimes it spins backwards at a more normal speed for a short while and then stops after spinning slowly for a bit.
- Sometimes tray doesnt open
- Sometimes the display is completely dim, no leds at all (and sometimes it blinks here and there).
- There is no eye pattern as no CD can be read (same as before)
I checked the VCO, seems there is no PLL lock, at least I don't get a good signal irrespective of the VCO pot setting (procedure as per service manual).
From the erratic behaviors I suspected bad soldering and resoldered all IC connections. Also used freeze spray. No difference.
I see the laser moving up upon power up, but nothing more than that. There is no current flowing (same as before), and no red light. I guess the player doesnt run through its startup routine enough to power up the laser.
Check you don't have any shorts on the servo chip between pins. Liquid solder flux (for electronics) will help keep the solder on the pins and pads. You may also have a pin not connected.
With high current draw, don't expect to be able to troubleshoot anything. The supplies have to be clean and stable.
With high current draw, don't expect to be able to troubleshoot anything. The supplies have to be clean and stable.
Still trying to bring back this one... I replaced the driver IC CXA1082, and after initially some seeming solder joint problems, the behavior is now very similar to previously.
The following is under the only condition of the player, power on, no disc loaded.
The following is under the only condition of the player, power on, no disc loaded.
- DIsplay - no change. The display still consistently shows the wrong data. It's nice and bright, I see the '1' (As it should upon startup), but also some segments light up and flash in sync with the flashing 'disc' led. When I press repeat, both the 'repeat' led and one of the segments in the display come on. I already swapped some of the display driver ICs which didnt result in different behaviors. The connections to the MPU are good. Hoping that solving the other issues would fix this too...
- Sled movement to far outer edge - no change. It still moves to the far outer edge. Did a lot of testing of the gears and motors with a battery and such. Conclusion is that it's not the mechanical part. Measurements to the servo IC:
- Feed motor amp output (SLO) +0.7V - why does it keep pushing to the outer edge?
- Non-inverting input of the feed motor amp (SL+) +0.5V - I can't really interpret this?
- Inverting input of the feed motor amp (SL-) -1.5V - I can't really interpret this?
- I have replaced the driver buffer STA341 already. It gets very hot, unsurprisingly, as its being pushed to the outer edge by the driver. Both old and new STA341 same behavior.
- Spindle - change from spinning fast clockwise to spinning fast counterclockwise. On Philips chipsets this could be due to clock signals, so checked those out. System clock is ok. Measurements to the servo IC:
- Non-inverting input to the disc motor amp (SPDL-) +5V - shouldn't this be a negative voltage??
- Disc motor amp output (SPDLO) -5V
- The VCO frequency is suspect, it should be 8.64Mhz but on my analog scope I think I see a different frequency (too low). Adjusting the VCO pot trimmer does not allow me to get to 8.64Mhz. Requires more investigation. Question: what would be symptoms of incorrect VCO / no PLL lock?
Hi studiostevus,
The VCO frequency is not suspect unless it is way out of dead. The VCO only affects the spindle speed and decoding (since it has to lock to read data).
At this point I would have to see it on my bench to be able to say anything intelligent. You're at the point where a seasoned tech should be looking at it. You actually reached that point earlier in time. Electronic service isn't always easy.
The VCO frequency is not suspect unless it is way out of dead. The VCO only affects the spindle speed and decoding (since it has to lock to read data).
At this point I would have to see it on my bench to be able to say anything intelligent. You're at the point where a seasoned tech should be looking at it. You actually reached that point earlier in time. Electronic service isn't always easy.