I got a very trashed Sony CDP-215 a super basic mid 90's player. I just wanted to make it run for fun so I replaced loading belt and pickup (a KSS-240a) and it worked. I then decided to give it a clean so i took it apart and cleaned most of it to make it at least presentable. Upon reassembly it no longer works, the disc spindle start rotating in both direction and the lens is moved all the way up.
I checked with the finger on the BD board controlling the pick-up and an IC gets pretty hot within seconds. Referring to the attached image is the IC on the right, the driver for all the actuators (motors and coils). Is it toast ?
I checked all connections and everything looks fine; I tried several other KSS-240 and it always behaved the same regardless the pick-up was actually working or not. On the BD board there are very little components that can go wrong, no electrolytic's, no transistors, just two IC's, several resistors and ceramic caps. The pickup is entirely controlled by this board, the main board receives the PCM data already decoded and just instructs the BD board to play, stop pause and skip.
Very likely that IC is toast, I do not know how I did it, but this player has been heavily used.
Any idea ?
thanks
I checked with the finger on the BD board controlling the pick-up and an IC gets pretty hot within seconds. Referring to the attached image is the IC on the right, the driver for all the actuators (motors and coils). Is it toast ?
I checked all connections and everything looks fine; I tried several other KSS-240 and it always behaved the same regardless the pick-up was actually working or not. On the BD board there are very little components that can go wrong, no electrolytic's, no transistors, just two IC's, several resistors and ceramic caps. The pickup is entirely controlled by this board, the main board receives the PCM data already decoded and just instructs the BD board to play, stop pause and skip.
Very likely that IC is toast, I do not know how I did it, but this player has been heavily used.
Any idea ?
thanks
Attachments
That is the servo driver IC. It has four sections:
Common sled system faults:
1) Dirty contacts on “home position” detector switch. This is a small leaf switch which closes when the sled moves all the way towards the center of the disc. At power-up and after closing the CD tray, the first thing that happens is the MCU commands the sled motor to rotate in the direction to move the sled towards the center. As soon as the home position detector switch closes, the sled motor is switched off and the next thing that happens should be “focus search” where the optical pickup lens moves up and down. DC resistance of the detector switch should <1 ohm and be stable when the leaf switch is closed. See below for more details about testing/cleaning the home position detector switch.
2) Faulty sled motor, especially a partial short-circuit between 2 of its commutator bars. These small DC motors have only 3 poles on their armature. Therefore the commutator has only 3 copper bars. The brushes are usually nothing but a thin strip of springy metal. They can wear away or simply break off, or a burr at the worn section can “catch” in the slot between 2 commutator bars. This will cause either an open circuit or a short circuit. In either case the sled motor won’t rotate. Or it will only function intermittently. More details on testing sled motors are given below.
3) Mechanical issues: Broken or deformed teeth on the plastic gears or the rack gear. Dried grease. Foreign material. The sled needs to be able to move freely and smoothly. The typical Sony transport used with the KSS240A has 2 plastic gears. These can be removed by carefully rotating the plastic arms which retain them. Also the sled motor is attached with 2 small screws. Unbolting and removing the sled motor permits testing the gear train & sled for free motion. Note that the servo PC board must first be unsoldered from both the spindle motor and sled motor in order to gain full access to them. Alternately the plastic gears can be removed (one at a time) to evaluate the rest of the drive train. Bent gear teeth can sometimes be gently straightened and burrs trimmed off with a sharp knife. The goal is for the gear train to operate smoothly without tight spots or hang ups.
Details for checking sled drive motor and home position detector switch:
If the sled moves to the center, but the lens never moves up and down afterwards, this indicates a dirty home position detector switch.
Testing the small DC motors (sled and spindle motors):
Both the sled drive and spindle motors can be tested by applying 0-6V DC from a variable power supply. The motor current should be <50mA at voltages up to 6V. The motor should begin to rotate smoothly when the applied voltage reaches 1V. At 6V the motor should rotate at 1,000 to 2,500 RPM. The motor should perform the same in both directions of rotation. This can be tested by reversing the DC polarity applied to the motor.
Important: When testing a sled motor, always remove one of the plastic drive gears first, or test the sled motor while the optical pickup is removed. This prevents driving the optical pickup sled against the end stops which may damage the plastic teeth on the gears or the rack.
The following post provides more detail for motor and switch testing:
DENON DCD S10/ Servo adjustment
Best of luck to you! I have successfully restored a whole bunch of these CD players which use the KSS240A optical pickup.
-EB
- Two sections drive the focus/tracking actuator coils which move the lens on the KSS240A optical pickup.
- The third section drives the spindle motor.
- The fourth section drives the sled motor. This is the motor which engages with 2 plastic reduction gears and finally a toothed rack gear on the KSS240A itself. This mechanism moves the optical pickup back and forth. It is commonly known as the “sled drive.”
Common sled system faults:
1) Dirty contacts on “home position” detector switch. This is a small leaf switch which closes when the sled moves all the way towards the center of the disc. At power-up and after closing the CD tray, the first thing that happens is the MCU commands the sled motor to rotate in the direction to move the sled towards the center. As soon as the home position detector switch closes, the sled motor is switched off and the next thing that happens should be “focus search” where the optical pickup lens moves up and down. DC resistance of the detector switch should <1 ohm and be stable when the leaf switch is closed. See below for more details about testing/cleaning the home position detector switch.
2) Faulty sled motor, especially a partial short-circuit between 2 of its commutator bars. These small DC motors have only 3 poles on their armature. Therefore the commutator has only 3 copper bars. The brushes are usually nothing but a thin strip of springy metal. They can wear away or simply break off, or a burr at the worn section can “catch” in the slot between 2 commutator bars. This will cause either an open circuit or a short circuit. In either case the sled motor won’t rotate. Or it will only function intermittently. More details on testing sled motors are given below.
3) Mechanical issues: Broken or deformed teeth on the plastic gears or the rack gear. Dried grease. Foreign material. The sled needs to be able to move freely and smoothly. The typical Sony transport used with the KSS240A has 2 plastic gears. These can be removed by carefully rotating the plastic arms which retain them. Also the sled motor is attached with 2 small screws. Unbolting and removing the sled motor permits testing the gear train & sled for free motion. Note that the servo PC board must first be unsoldered from both the spindle motor and sled motor in order to gain full access to them. Alternately the plastic gears can be removed (one at a time) to evaluate the rest of the drive train. Bent gear teeth can sometimes be gently straightened and burrs trimmed off with a sharp knife. The goal is for the gear train to operate smoothly without tight spots or hang ups.
Details for checking sled drive motor and home position detector switch:
- The first test is done with no disc in the tray and power off.
- Gently rotate the smaller sled drive gear to move the sled outward towards the outside edge of the disc. Don’t force it. There are mechanical stops at both ends.
- Then switch on the power.
- The sled should move steadily towards the disc spindle.
- When it gets all the way to the home position then the optical pickup lens should move up and down. This the “focus search.”
If the sled moves to the center, but the lens never moves up and down afterwards, this indicates a dirty home position detector switch.
Testing the small DC motors (sled and spindle motors):
Both the sled drive and spindle motors can be tested by applying 0-6V DC from a variable power supply. The motor current should be <50mA at voltages up to 6V. The motor should begin to rotate smoothly when the applied voltage reaches 1V. At 6V the motor should rotate at 1,000 to 2,500 RPM. The motor should perform the same in both directions of rotation. This can be tested by reversing the DC polarity applied to the motor.
Important: When testing a sled motor, always remove one of the plastic drive gears first, or test the sled motor while the optical pickup is removed. This prevents driving the optical pickup sled against the end stops which may damage the plastic teeth on the gears or the rack.
The following post provides more detail for motor and switch testing:
DENON DCD S10/ Servo adjustment
Best of luck to you! I have successfully restored a whole bunch of these CD players which use the KSS240A optical pickup.
-EB
Some more things to look at:
Is there any chance of an accidental short circuit or solder bridge?
Check the flat flexible cables very carefully for loose, bent, or broken contact fingers at their ends. I have successfully repaired damaged flat flex cables by trimming off about 1mm from the damaged end with a very high quality scissors.
The servo IC operates entirely with a 9V positive supply rail. There are no negative supply rails. Just ground and +9. Check all the DC voltages shown on the schematic for the servo IC pins. They should be close to what is listed on the schematic.
With the flat cable to the optical pickup unplugged and the servo PC board unsoldered from the spindle and sled motors, then there is no load on the servo IC. Under this test condition it should not warm up above room temperature when power is applied. Should the servo IC still get very hot with all loads disconnected then it might actually be faulty.
-EB
Is there any chance of an accidental short circuit or solder bridge?
Check the flat flexible cables very carefully for loose, bent, or broken contact fingers at their ends. I have successfully repaired damaged flat flex cables by trimming off about 1mm from the damaged end with a very high quality scissors.
The servo IC operates entirely with a 9V positive supply rail. There are no negative supply rails. Just ground and +9. Check all the DC voltages shown on the schematic for the servo IC pins. They should be close to what is listed on the schematic.
With the flat cable to the optical pickup unplugged and the servo PC board unsoldered from the spindle and sled motors, then there is no load on the servo IC. Under this test condition it should not warm up above room temperature when power is applied. Should the servo IC still get very hot with all loads disconnected then it might actually be faulty.
-EB
Out of curiosity, today I took apart the control board to inspect it again:
there are no obvious problems, no short, no bad solder joints, no loose connections. The spindle and sledge motors work fine in both directions; the flat cable to the pickup is fine (tested each wire), both voltages are there (regulated 5V and unregulated 7V)
Disconnecting the pick-up, the driver IC does not gets hot so I guess it overheats due to the lens kept constantly in the upper position (and the current flow associated), so I think actually it is the monolith IC that controls the pick-up to be at fault, It behaves erratically and completely out of logic: It randomly spins the spindle in both directions, sometime it moves the pick-up all inward and does not stop when it hits the rest switch (the switch is fine, checked with multimeter), it moves the lens all upward and sometimes drop it all down.
I do not know what is wrong with this player, but it is absolutely not worth fixing it, it is in such bad state it would not be nice anywhere in a home. It was just a fun exercise.
thanks.
there are no obvious problems, no short, no bad solder joints, no loose connections. The spindle and sledge motors work fine in both directions; the flat cable to the pickup is fine (tested each wire), both voltages are there (regulated 5V and unregulated 7V)
Disconnecting the pick-up, the driver IC does not gets hot so I guess it overheats due to the lens kept constantly in the upper position (and the current flow associated), so I think actually it is the monolith IC that controls the pick-up to be at fault, It behaves erratically and completely out of logic: It randomly spins the spindle in both directions, sometime it moves the pick-up all inward and does not stop when it hits the rest switch (the switch is fine, checked with multimeter), it moves the lens all upward and sometimes drop it all down.
I do not know what is wrong with this player, but it is absolutely not worth fixing it, it is in such bad state it would not be nice anywhere in a home. It was just a fun exercise.
thanks.
Yes. I've changed some of these BA IC's, and doing experiments I've broken some of then too. It is not rare that it got broken. If all is normal, and it get hot, the BA is the most probable cause. If you don't have hot air gun for this, this tool can help you.
AC 220V 450W 450℃ 8018LCD Soldering Station Heat Hot Air Gun ICs SMD 4 Nozzles | eBay
AC 220V 450W 450℃ 8018LCD Soldering Station Heat Hot Air Gun ICs SMD 4 Nozzles | eBay
I also thought back on how I could have broken it and it was very likely due to a series of mishaps on my part.
The switch that should put the CD player in standby does not work properly, it turns off the display, but it does not cut the 5V due to a bad contact inside the switch itself. I'm quite sure that at one point I have connected the big green flat cable from the main board to the BD board with the line plugged in and just the main switch set to stand-by (which due to the faulty switch is like being fully powered on). That is 101 of CD player maintenance, but given I do not care much for this player i have been careless and broke it. It will go back to the recycle centre (that is where mostly likley it comes from in the first place).
The switch that should put the CD player in standby does not work properly, it turns off the display, but it does not cut the 5V due to a bad contact inside the switch itself. I'm quite sure that at one point I have connected the big green flat cable from the main board to the BD board with the line plugged in and just the main switch set to stand-by (which due to the faulty switch is like being fully powered on). That is 101 of CD player maintenance, but given I do not care much for this player i have been careless and broke it. It will go back to the recycle centre (that is where mostly likley it comes from in the first place).
Sony used a similar small servo PC board in numerous models which also use the KSS240A optical pickup. One way I manage my vintage audio gear collection is to watch garage sales (and free items on the curb) for similar models. For example I recently restored 3 single-disc Sony CD players and 2 Sony 5-disc carousel CD players which all contained identical KSS240A optical pickups and servo PC boards. With multiple interchangeable parts and PC boards the diagnostic process becomes much easier.
So before you recycle this unit with the bad servo PC board you might want to look for other units which are similar. There are probably many parts in your malfunctioning unit which are still good.
-EB
So before you recycle this unit with the bad servo PC board you might want to look for other units which are similar. There are probably many parts in your malfunctioning unit which are still good.
-EB
Clock(s) is(are) generated off board (not on the BD) on this mecha
If the clock is not present you get weird symptoms , there is an arcam with the same sony BD board/240 and that misbehaves with clock problems. (lens hits the endstop and often the sled will traverse to outer edge)
(Clock(s) might be bad due to PSU problems on main board)
If the clock is not present you get weird symptoms , there is an arcam with the same sony BD board/240 and that misbehaves with clock problems. (lens hits the endstop and often the sled will traverse to outer edge)
(Clock(s) might be bad due to PSU problems on main board)
Actually for now it is going in storage for spare parts, it will end-up in recycle centre if I run out of space in the storage.
In the past I have swapped the entire BD/pick-up assembly between two very different players (CDP-X222ES and CDP-S41) because it was the very same version and I wanted to have an original Sony KSS-240a in the X222ES (still working fine as of today). I have another Sony CDP-M33 which uses KSS-240a but it has a different revision of BD board and, most importantly, it works fine and it is in excellent cosmetic conditions so I'm not risking to ruin a working player to fix this one.