Sunday, 26 May 2013

Philips CD150

The Philips CD150 was one of the first cheaper CD players that Philips made.  This player was released in 1985; CD players were no longer new and the technology was starting to mature.  Quite a few steps had been taken to lower the production costs of this player and players like it, including:

  • A new laser mechanism.  The CDM0 and CDM1 have a prototype feel to them, they're large, they have many parts and are made of expensive materials.  The CD150 uses the CDM2.  For the CDM2 both the chassis and laser swingarm arm made of plastic and the spindle motor is a much more compact PCB based brushless design.
  • An IC based servo.  Earlier CD players had complex servos based on discrete semiconductors and low level integration (such as opamps and logic ICs).  The CD150 uses the new TDA5708 photodiode signal processor and TDA5809 radial error signal processor ICs.  This cut down both the component count and the PCB area the servo occupies.
  • A standard PCB layout.  This player has three significant PCBs; the servo board (underneath the laser mechanism), the mainboard (on the right side of the player) and the front panel board.  Philips made a fair few players during this era with the same layout.  Compared to earlier CD players with multiple stacked PCBs these were easier to construct and service.
  • A cheaper case.   Most of the other changes were positive, this one isn't.  The CD150's case is fairly well designed, but it lacks rigidity.  When the lid is removed it's laughably flexible, and the larger full width players, like the CD350, are even worse.

As you might notice this image is a bit different to what I normally upload.  It's on my workbench, this post will be about how to do a capacitor replacement as well as some basic upgrades.  This player is a good candidate, it's stock standard and still working, but it's starting to struggle to read a CD.


This job requires tools that are specific to electronics.  Some are essential, some are optional.  We'll start with the essentials:
  • A soldering iron.  You'll need an iron suited to electronics with a reasonably fine tip with a power of 15 to 30W and a ceramic element.  Don't use a large high powered one with a nichrome element, they're best used for burning marks into wood.  I used to use an Antex XS25, it was okay.  You'll also need a stand and a wet sponge to clean the tip.
  • Solder.  Leaded solder is easier to work with and more forgiving of poor technique, so I'd recommend that, though I realise it's hard to get anything other than lead free in some places.  Whichever you get, make sure it's a good brand solder with multiple flux cores.  I use Henkel Multicore 362, 60/40 leaded solder with a rosin flux.  The solder diameter should be 0.75mm (22SWG) or less.
  • Desoldering tools.  There are a couple of options here.  You can use either desoldering wick (sometimes called desoldering braid) or a desoldering pump (sometimes called a solder sucker).  I mostly use a desoldering pump, maybe take a look at how they're used later in this post to decide which you prefer.  For the wick, only buy a name brand, cheap brands don't work.  Don't buy brand name wick from China on eBay, it's often counterfeit and again won't work.  I use Edsyn Soldasip SW091.  Generic solder pumps will work okay, but name brand ones work better.  I use an Edsyn Soldapullt SS750LS.
  • Cutters.  Try to get a pair or proper electronics cutters, rather than diagonal pliers.  I use Hakko CHP-170 cutters, they're cheap and they work very well.
  • ESD protection.  This is an item many overlook, but it's essential, at least if you want the CD player to work after you've finished with it.  You're going to need a mat and a wrist strap with a cord.
  • Screwdrivers.  Most of you will already have a general purpose screwdriver set, but for older Philips players you'll need a Torx T10 driver as well.

Additionally there are a few optional ones:
  • A soldering station.  An ordinary soldering iron doesn't work very well.  If the power is low it will be too cold to solder larger components properly.  If the power is to high it'll overheat smaller components and burn of the flux.  A soldering station is temperature controller, and varies the power to its soldering iron so that you can solder both larger and small components well.  I use a classic Hakko 936, which is a good soldering station.  You can pick up one of the second hand market or buy its replacement new, the Hakko FX888.  Goot also make nice soldering stations, as do Pace and Metcal, though I only have personal experience with Hakko and Goot.
  • Test equipment.  In an ideal world you wouldn't need it, but if your repair is unsuccessful, you're blind without it (literally, electrons are very hard to see).  The main instruments I'd use when troubleshooting a CD player are a multimeter and an oscilloscope.

Okay, you've got the tools, now you need the materials.  The first step is forming a bill of materials, or BoM (a list of what electronic components you need).

There are a few was to make a BoM.  The service manual is available for free online for most of these older Philips players, including the CD150.  Nostatech is a great resource for Philips service manuals.  You can make the BoM simply by reading the manual, which will list all of the components.  However, my prefered method is to remove the PCBs and read the values directly off the capacitors.  Often the service manuals won't list the voltage rating (which you need to know), and sometimes aren't consistent with the actual device.  When making a BoM for a capacitor replacement you need to note the capacitance and voltage rating of each component.  You may also want to note the diameter if the capacitor is in a tightly packed area (so that you don't get a replacement that is to large to fit) and its function.  Here is an example, the BoM I wrote for the CD150:

6800u/16 1 2416
1000u/16 1 2417
330u/25 2 2402, 2418
100u/25 1 2419
47u/10 7 2320 (DAC dec.), 2321 (DAC dec.)2388, 2396 (digital filter dec.), 2397, 2410, 2411
47u/25 10 2309,  2362, 2365, 2380 to 2383 (opamp dec.), 2412, 2413, 2414
100u/10 2 2384, 2385 (both output coupling)
10u/63 2 2330, 2331 (both DAC bias filtering)
220u/63 1 2420
1u/63 1 2313
47u/25 3 2052, 2056, 2058 (all axial)
1u/63 1 2053 (axial)
47u/10 2 2104, 2107
33u/16 1 2103
47u/25 1 2173
1u/63 1 2174
1.5u/50 1 2159 (bipolar)
220u/10 3 2127, 2138, 2140

As you can see above, I've identified a few capacitors that I'll give special treatment.  These are:

  • DAC, digital filter and output stage opamp decoupling capacitors (2320, 2321, 2393, 2380 to 2383).  These capacitors are located close to their respective components and have a large impact on the quality of power supply that each component sees.
  • Coupling capacitors (2384, 2385).  These are used to block any DC at the players output, so that the player only outputs AC.  These are critical to sound quality.  They can be replaced with film capacitors, but their size adds another set of issues, so I'll stick with compact electrolytic capacitors.  
  • DAC biasing capacitors (2330, 2331).  These are part of the circuit that nulls the offset of the DAC ICs current output.  A low impedance type will help here.
  • Axial capacitors (2052, 2053, 2056, 2058).  This form factor, where the leads are attached to both ends of the body, has gone out of common use in favour of radial packages, where both leads are attached to one end of the body.  Axial capacitors are used in all three boards in this player, but in most cases a radial capacitor will fit okay.  On the front panel board there isn't room to stand a radial capacitor upright, so I'll use axial replacements.  You could use radial capacitors, but it will look untidy and possibly be less mechanically reliable.
  • Bipolar capacitor (2159).  This capacitor filters the output of the radial motor driver, and can cause problems in some cases.  I prefer to replace it with a film capacitor, but a replacement bipolar electrolytic will also work.
So that covers the type of capacitors needed, now I need to determine the capacitance and voltage ratings.  I won't get replacements that exactly match the originals, it just isn't necessary.  When choosing a replacement's capacitance, you should stick to the same value as the original unless you understand what its function is, and the implications of making a change.  For example, increasing the value of the four 100uF opamp decoupling capacitors isn't a bad idea, but increasing the value of the 1uF capacitors (part of the microcontroller reset circuit) could disable the player.

When choosing a replacement's voltage rating, in general sticking to a rating the same or higher is fine.  However, there are a couple of exceptions:
  • Don't increase the voltage rating excessively.  If you try to replace a 220uF/10V capacitor with a 220uF/200V one you may find it simply won't fit, as size increases with voltage rating.  Electrolytic capacitors also diminish in performance in some respects with voltage rating, the sweet spot is 35V.
  • Some capacitors have a voltage rating far higher than necessary.  Often these are low capacitance, and are only available in high voltage ratings.  An example in the CD150 is the two 1uF/63V capacitors.  They only have 5V across them, so it would absolutely fine to replace them with 1uF/50V or 1uF/35V rated capacitors.  To consider reducing a voltage rating, you must know exactly what the capacitor will be exposed to.
Now that we've established what capacitances and voltage ratings we need and what special requirements some particular capacitors have we can actually make a final BoM to order.  Here's what I came up with for this player:

1u/63 2 EKMG500ELL1R0ME11D Nippon Chemicon
1u/63 1 MAL203038108E3 Vishay BC
1.5u/50 1 BSME500ELL2R2ME11D Nippon Chemicon
10u/50 2 ELXY630ELL100MEB5D Nippon Chemicon
33u/35 1 EKMG350ELL330ME11D Nippon Chemicon
47u/25 3 MAL203036479E3 Vishay BC
47u/35 13 EKMG350ELL470ME11D Nippon Chemicon
56u/35 7 ELXY350ELL560MFB5D Nippon Chemicon
100u/10 2 UES1E101MPM Nichicon
100u/35 1 EKMG350ELL101MF11D Nippon Chemicon
220u/25 3 EKMG350ELL221MHB5D Nippon Chemicon
220u/50 1 EKMG500ELL221MJC5S Nippon Chemicon
330u/25 2 EKMG250ELL331MHB5D Nippon Chemicon
1000u/16 1 EKMG160ELL102MJ16S Nippon Chemicon
6800u/16 1 EKMG160ELL682MLN3S Nippon Chemicon

This list was not only based on what I prefer, but what was available to me at a good price.  By default I chose Nippon Chemicon KMG series.  These are a general purpose 105°C capacitor from a brand I trust.  I normally use 105°C rated capacitors, they're only slightly more expensive than 85°C rated ones, but will last much longer.  For the critical decoupling capacitors I chose Nippon Chemicon LXY series, a long life low impedance type.  For the DC blocking capacitor I chose Nichicon ES series, a good quality bipolar electrolytic that sounds better than most.  For the bipolar capacitor in the servo I chose Nippon Chemicon SME-BP series, a general purpose bipolar type.

You've got to make decisions about what you buy based on what's available to you.  It's no use making a list like this without knowing that they'll be in stock at a reasonable price.  Which electronics seller will be best for you depends on your location, the following are worth considering; Farnell / element14 / Newark, Digikey, Mouser and RS.  These serve the Asia Pacific region, there are more that serve other parts of the world.  I also use PartsConnexion for audio-specific components.  I don't recommend eBay, it looks good on the surface, but the value coverage and quality is quite patchy.

As part of this I'll also replace the output stage opamps.  This player originally used LM833s, one per channel.  One half is the I/V converter, the other half is a buffer.  Though most modern dual opamps in an 8DIP package share the same pinout, they're not universally interchangable.  I decided on an OPA2134 as a replacement, it has good performance, it is not too fast, it is unity gain stable (the buffer has unity gain) and it is widely available.  There are many good opamps, but unless you understand what to look for in a replacement and have an oscilloscope to check for stability, I'd stick to the OPA2134.


Now that you've got a pile of fresh capacitors, it's time to remove the old ones.  The boards in this player are actually double sided, but they're not through hole plated, so the techniques are the same as what you'd use on a single sided board.  At the same time you're desoldering the components you'll need to think about how you'll know what values go where and their polarity when you come to soldering in the new capacitors.  The easiest way is to only desolder and replace one value at a time.

To note polarity you can mark the board (I put a dot next to the negative lead, the one marked by a stripe or ring on the capacitor).  I also like to take a photo before the replacement that I can compare with the end result.  It's best to rely on these method rather than to use the diagram in the service manual or the board's silkscreen (on more modern PCBs than this example), as both of these are often wrong.  The service manual digram for the CD150 shows the wrong polarity for both 2380 and 2309.

On these types of boards I'll use two different techniques, depending on how the components were mounted.  For smaller components, like resistors, diodes, TO-92 transistors and electrolytic capacitor less than 8mm, the legs of the components were bent over to hold them to the board during wave soldering.  Larger, heavier components were simply placed, their own weight would be adequate to keep them in place.

On the smaller components, the leads are usually accessible from the top side.  I cut the leads as close to the board from the top side.  I then add fresh solder to the joints from the bottom side then remove both the solder and lead remained using the desoldering pump.

On the larger components, where the leads aren't bent, I'll add solder to the joints from the topside, then use a desoldering pump to remove the solder.  If this is done cleanly, the component should pull out easily from the top, or even drop out.  If the component isn't free, check that each lead is loose when pressed with, say, a fine screwdriver.  Add fresh solder and reapply the desoldering pump as necessary to free each lead.


Like I mentioned above, you'll probably want to install the new components as you remove the old ones.  How to solder is something that has been done many times, this video here is quite good, if you're unfamiliar with soldering I suggest you watch it.  The main thing is to check that the component you're installing is the right value and the polarity is correct.

Unfortunately these older PCBs are quite fragile.  When you're desoldering components it's easy to damage the tracks or pads on the board.  If you do this, don't ignore it.  the best way to fix the problem is to bend the lead through the damaged pad and solder it to another pad that it would normally be soldered to.  Even though I was very careful with the CD150's board, half of a pad on one of the capacitors lifted.  Here is a photo of how I repaired that:

Here are the boards after the replacement:

Powering Up

Now the the repair is complete it needs to be tested.  I recommend that you once again check that all the components are installed with the correct polarity.  If the polarity is wrong the electrolytic capacitors may explode, and the opamps would be destroyed.

Reassemble the boards into the player and reconnect the cables.  If you're unsure about the cabling, check the wiring diagram in the manual.  You should also check the motion of the laser mechanism's swingarm when you have screwed the servo board to it.  It should swing freely throughout its arc, if it doesn't you may have installed a capacitor that is too tall.  If that is the case, remount the capacitor on its side or use an axial leaded capacitor.

When testing a new repair, it is good practice to slowly power it up using a variac while monitoring its current consumption.  However, a CD player is a low power appliance, so that's not strictly necessary.  If you don't have a variac, power the player up while wearing safety glasses and prepare to turn it back off if anything sounds, smells or looks wrong.  Don't connect the outputs to anything during this first power up.

If all goes well, connect the player to the rest of your sound system, put a disc in and try it out.  Check it plays both pressed CDs and burned CD-Rs and check it plays well without skipping from the first to the last tracks.  Hopefully it all works fine.  If it doesn't, it's troubleshooting time.  A CD player is a fairly complex piece of electronics, so troubleshooting a bad repair is going to be a hard ask for a beginner.  It's best to start out with a cheaper player like a CD150, wrecking one of these is no great loss.  Wrecking something like a Marantz CD16 on the other hand... (I've had to recover one of these from a upgrade gone wrong before).