Hi Folks, I picked up a Nakamichi CDP 2E (same as 2A for European market), which is faulty. Chipset is CXA1082BQ (servo IC), CXD1135Q (DSP), CXD1088Q (digital filter), CXA1081M (RF Amp), NEC PD75108 (MPU). Sony KSS-152A and TDA1541A dac.
The online service manuals do not include the schematic, nor expected voltages/signals.
Symptoms
Analysis - performed at "power on but no CD loaded" state
Hypotheses
Any ideas on where to look further?
The online service manuals do not include the schematic, nor expected voltages/signals.
Symptoms
- Spindle spins (clockwise) from power on, irrespective of a CD loaded.
- Sled/feed motor spins towards the center from power on, irrespective of a CD loaded.
- Display is jibberish, some segments light up. If I press play, an additional segment lights up. 'disc' led is flashing. Responds normally to pressing repeat, mute.
- Laser comes up upon powering on, but given all of the above makes no attempt on focusing.
- Tray open/close is ok.
Analysis - performed at "power on but no CD loaded" state
- Spindle
- transistors feeding the motor seem ok, fed by +/-11V and receiving a 3.3V signal from the servo IC (waveform + DC).
- checked "MON" (motor ON) signal between Servo IC and DSP, there is some waveform with a peak at 1V. What is the expected value here?
- This would point at something wrong with servo IC, or incorrect inputs into servo IC.
- Sled/feed motor
- The leaf switch indicating max sled position is working fine.
- According to the block diagram the sled is driven by a a different section of the servo IC. A fault in both sled and spindle suggests faulty servo IC?
- Servo IC
- Input voltages are correct
- "C864" (VCO frequency) pushes out a nice clean square wave, Makes me think the Servo IC is fine? (at least that part)
- Next suspect if not the Servo IC: DSP IC
- Display problems
- I cannot see how problems at either Servo IC or DSP would result in jibberish in the display, as this is driven from the MPU.
- Suggest problems with the MPU?
- Clock (16MHz) - often the culprit in case of erratic problems
- Arrives in good shape in the Digital Filter IC
- Not entirely sure how it is propagated further to the other chips
- Temperature with IR gun - none of the chips run particularly hot (servo at 30C, the rest at 23C after some minutes)
Hypotheses
- Servo IC is faulty or incorrect input signals
- DSP IC is fault or incorrect input signals
- MPU is faulty or incorrect input signals
Any ideas on where to look further?
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Check your DC power supplies first. Use an oscilloscope before the regulators and after. Also look for oscillation on the regulated DC power.
I did warranty on these when they were brand new and have serviced them since. Very few odd problems.
Also, check the disc table height.
Spindle spins (clockwise) from power on, irrespective of a CD loaded. - they may, I can't remember.
Sled/feed motor spins towards the center from power on, irrespective of a CD loaded. Absolutely normal, it is finding out where the laser is to initialize reading the TOC.
Display is jibberish, some segments light up. If I press play, an additional segment lights up. 'disc' led is flashing. Responds normally to pressing repeat, mute. The display may be bad, but this may also indicate the logic supply has problems.
Laser comes up upon powering on, but given all of the above makes no attempt on focusing. They normally come on to do a focus lock (disc) search. The lens should move but it can be hard to see. Look at the focus servo output (scope).
I did warranty on these when they were brand new and have serviced them since. Very few odd problems.
Also, check the disc table height.
Spindle spins (clockwise) from power on, irrespective of a CD loaded. - they may, I can't remember.
Sled/feed motor spins towards the center from power on, irrespective of a CD loaded. Absolutely normal, it is finding out where the laser is to initialize reading the TOC.
Display is jibberish, some segments light up. If I press play, an additional segment lights up. 'disc' led is flashing. Responds normally to pressing repeat, mute. The display may be bad, but this may also indicate the logic supply has problems.
Laser comes up upon powering on, but given all of the above makes no attempt on focusing. They normally come on to do a focus lock (disc) search. The lens should move but it can be hard to see. Look at the focus servo output (scope).
To clarify: the sled motor keeps running without stopping when the leaf switch is engaged.
Okay, the leaf switch may have intermittent contacts, or a wire is broken to the plug. Rarely, I have seen traces broken at the plug on the PCB when a rough "technician" attempts to service things.
First, use an oscilloscope to check your power supplies.
First, use an oscilloscope to check your power supplies.
All voltages are correct, only a significant ripple at the spindle motor supply (but that is to be expected?).
The leaf switch is functional and it’s signal arrives at the MPU.
The leaf switch is functional and it’s signal arrives at the MPU.
U103, pins 4 and 6. What do you read? That's the feed motor driver.
TP109 DC voltage? The feed amp input gets a low pass filtered version of TP109.
U102, should look at the control signals from the main controller.
TP109 DC voltage? The feed amp input gets a low pass filtered version of TP109.
U102, should look at the control signals from the main controller.
U103 pin 4 Is -2.5v
U103 pin 6 is 1v
TP109 dc voltage is -0.1v
U102 control signals from U107 for feed control
CLK ac signal squarish 2mV on top of 4.7V DC
XLT ac signal squareish 2mV AC on top of a 4.7VDC
Data signal L=0V H=0.18V, looks clean
U102 control signals from U106 for spindle control
MON 0Vdc with a ripple on top
MDP 0Vdc with a ripple on top
Thanks for your help so far!
Also I was wondering why your first line of investigation is along the feed trail rather than spindle? I was looking at spindle first (probably because the spindle is more noisy and attracted my attention more than the feed. Both are unable to stop as long as the player is powered up)
U103 pin 6 is 1v
TP109 dc voltage is -0.1v
U102 control signals from U107 for feed control
CLK ac signal squarish 2mV on top of 4.7V DC
XLT ac signal squareish 2mV AC on top of a 4.7VDC
Data signal L=0V H=0.18V, looks clean
U102 control signals from U106 for spindle control
MON 0Vdc with a ripple on top
MDP 0Vdc with a ripple on top
Thanks for your help so far!
Also I was wondering why your first line of investigation is along the feed trail rather than spindle? I was looking at spindle first (probably because the spindle is more noisy and attracted my attention more than the feed. Both are unable to stop as long as the player is powered up)
U103 pins 4 and 6 should be close to the same voltage. The STA341 is just a buffer and you were wondering about logic problems. So the feed motor should stop but doesn't. Why? There is one of your answers. To be honest, I haven't seen one of those fail before. Make sure you have supply voltages on pins 1 (+11V) and 5 (-11V). If you are missing one, say negative, that might explain it. It also may be your issue with the spindle (disc) motor.
The one common issue is the ball bearing in the clamper wears a "divot" in the clamp (flapper). If deep, put something thin and stiff over it, if shallow you may be able to sand it flat. Slippy lubricant on that ball.
The one common issue is the ball bearing in the clamper wears a "divot" in the clamp (flapper). If deep, put something thin and stiff over it, if shallow you may be able to sand it flat. Slippy lubricant on that ball.
I have a similar problem with an Onkyo. Turns out the spindle motor was short, and it took out the spindle motor IC. Maybe you can look into that?
Interesting
How did you diagnose that?
In my case the spindle motor is spinning continuously, did you have the same?
How did you diagnose that?
In my case the spindle motor is spinning continuously, did you have the same?
Initial symptoms were the control panel not responding at all, and the tray motor was turned on and spinning at a high speed. The spindle motor wasn't running. CD can't be loaded up at all.
Long story short, I opened a thread here and got some great help. Disconnecting the spindle motor stopped the tray motor from acting crazy and returned control of the control panel. From there I changed the spindle motor, and it turned out now the spindle motor was constantly spinning. More work ensued which resulted in the replacement of the spindle motor driver. Now the load sequence is ok.
Sadly, when I press play the whole system hangs up. So it's in storage until I get inspired again.
Long story short, I opened a thread here and got some great help. Disconnecting the spindle motor stopped the tray motor from acting crazy and returned control of the control panel. From there I changed the spindle motor, and it turned out now the spindle motor was constantly spinning. More work ensued which resulted in the replacement of the spindle motor driver. Now the load sequence is ok.
Sadly, when I press play the whole system hangs up. So it's in storage until I get inspired again.
Use your scope across the spindle motor and look at the waveform.
To really test, use a variable power supply and a 100R resistor. Increase the voltage to get the motor spinning slowly (not screaming). Look at either the current waveform (voltage across the resistor, or across the motor). A shorted winding will cause the voltage waveform to dead spot, the current waveform to peak.
While you are at it, rotate the motor around its axis slowly to see if you hear a knocking sound (= worn bearing),. These are common tests I do.
If the motor is really shorted and affects the entire system, you would have seen the power supply voltage drop or get very noisy. Always look at the power supplies.
To really test, use a variable power supply and a 100R resistor. Increase the voltage to get the motor spinning slowly (not screaming). Look at either the current waveform (voltage across the resistor, or across the motor). A shorted winding will cause the voltage waveform to dead spot, the current waveform to peak.
While you are at it, rotate the motor around its axis slowly to see if you hear a knocking sound (= worn bearing),. These are common tests I do.
If the motor is really shorted and affects the entire system, you would have seen the power supply voltage drop or get very noisy. Always look at the power supplies.
Nice scope. I use a PM3070 and PM3365A. It's a keeper!
That looks sort of normal, but the servo may interfere. Best to use a power supply to get a clear picture. Off-hand I would say it is okay. Now, do you hear bearing knock? That is only done at low speed, and you have to rotate the motor as it knock in one plane. The shaft is level.
That looks sort of normal, but the servo may interfere. Best to use a power supply to get a clear picture. Off-hand I would say it is okay. Now, do you hear bearing knock? That is only done at low speed, and you have to rotate the motor as it knock in one plane. The shaft is level.
Thanks, my old pm3250 broke and then I got this one.
No knocking or any inconsistency when turning the spindle manually.
I also disconnected the spindle motor to see the effect on the rest of the system, no change in the other symptoms (sled, display). Disconnected the sled motor, no impact on the other symptoms (spindle, display). Disconnected the display, no impact on the rest (spindle, sled).
Replaced some caps in the +/- 5V and +/- 11V supply, no sign of improvement.
Still puzzled, tending towards a logic issue still, based on the spindle behavior (servo doesn’t get a motor on signal but still sends a signal to turn on the spindle), and the combination of symptoms.
But your experience is vastly greater than mine…
No knocking or any inconsistency when turning the spindle manually.
I also disconnected the spindle motor to see the effect on the rest of the system, no change in the other symptoms (sled, display). Disconnected the sled motor, no impact on the other symptoms (spindle, display). Disconnected the display, no impact on the rest (spindle, sled).
Replaced some caps in the +/- 5V and +/- 11V supply, no sign of improvement.
Still puzzled, tending towards a logic issue still, based on the spindle behavior (servo doesn’t get a motor on signal but still sends a signal to turn on the spindle), and the combination of symptoms.
But your experience is vastly greater than mine…
The only way you can test the bearings without runningth e motor is to hold the shaft and spin the motor, allow it to slow down and stop. Try this in different positions with the axial shaft level. You might feel it knocking in one position.
No, your motor isn't causing electrical problems. That we know.
No, your motor isn't causing electrical problems. That we know.
Well I've done what you should do when you're in a hole... keep digging!
So I've bought a second Nakamichi CDP 2E... will be comparing them, hopefully that will reveal the problem(s).
On another note, upon opening the case, I now have one with a TDA1541A and one with a TDA1541 (no A)... strange.
So I've bought a second Nakamichi CDP 2E... will be comparing them, hopefully that will reveal the problem(s).
On another note, upon opening the case, I now have one with a TDA1541A and one with a TDA1541 (no A)... strange.
Hi studiostevus,
Probably an earlier serial number for the non-A. You won't notice any huge differences.
Most of this is experience. You need someone to show you, then you'll get it. It is next to impossible to tell someone what to look for and have them get it unless they see whatever it is for themselves. There are also so many things we look for when we have a machine open. We run through everything in our minds, so outside observers never see all that goes on. It looks easy, but we are taking in all kinds of clues, even down to smells and appearance.
Probably an earlier serial number for the non-A. You won't notice any huge differences.
Most of this is experience. You need someone to show you, then you'll get it. It is next to impossible to tell someone what to look for and have them get it unless they see whatever it is for themselves. There are also so many things we look for when we have a machine open. We run through everything in our minds, so outside observers never see all that goes on. It looks easy, but we are taking in all kinds of clues, even down to smells and appearance.