Philips CDI 450 General Maintenance

Exploded view of the CDI 450 from Philips's service manual: cover assembly (1), main panel (1001), shielding (22, 23), the CDM12.1T (31) on four suspensions (26 to 29) and the external power supply (301)

The Philips CDI 450 dates from 1994 and has three parts that need attention as it ages: the timekeeper NVRAM chip on the main panel, whose built-in battery runs down, the CDM 12.1T disc mechanism, and the external 20PS301 power supply with its RJ45 plug. Faults and measurements are on the Philips CDI 450 Troubleshooting Guide, and the capacitor list is on the Philips CDI 450 Capacitor Replacement Guide.

Safety

The player itself runs on +5 V and -5 V from the external supply; mains voltage is present only inside the 20PS301. Inside that supply the primary reservoir capacitor 2103 is rated 100 µF 400 V. Retrostuff's advice before opening a CD-i power supply is to unplug the mains cord and leave the power switch in the on position for some time, and it marks the large filter capacitors such as 2103 as a shock risk until they have discharged. It also warns against running a supply without a load. Check 2103 with a meter before touching the primary side.

The CDI 450 is a Class 1 laser product. Do not look into the lens when the lid switch is held down or the mechanism is running outside the case.

Philips's service manual asks for ESD precautions when handling the main panel and keeps soldering iron tips at the same potential as the board. Its tool sheet for SMD work shows an antistatic mat with a wrist lead, flux (4822 390 50025), desoldering braid (4822 321 40042), a Weller TCP 50 iron with a PT-CC7 tip (4822 310 50081) and 0.5 to 0.8 mm solder.

Tools and service parts

Philips's own list of accessories and service tools gives these part numbers.

Service tools (service manual section 8.4)

Philips code	Item
4822 395 50145	Torx screwdriver set
4822 321 61677	Cable for terminal (Low Level Test)
4822 264 50263	Plug for start-up of the Service Shell
4822 397 30096	Audio test disc set
4822 691 30293	Roller controller
4822 691 30298	Tracker ball
4822 691 30297	Mouse
4822 535 80819	Extension rods
4822 322 40066	Extension flexfoil

The cabinet parts list includes four Torx 3 x 22 screws (items 51 to 54). For general tools see Recommended Tools.

Opening the player

Philips gives no written disassembly procedure. The exploded view shows the order of the parts: the cover assembly (item 1, with the DVC door 2 and the disc door 3), the main panel 1001, the shielding cover 23 and the shielding bottom 22, the CDM12.1T (31) on four rubber suspensions (26 to 29), and the bottom 15. Photograph the cable runs before unplugging anything.

For work on a running board, Philips's service position stands the CD mechanism on four extension rods (4822 535 80819) beside the main panel and connects it through an extension flexfoil (4822 322 40066), with a wire to 0 V. Retrostuff plays discs on an opened CDI 450 without the metal shield and top cover: it lays a disc clamper from an old CD-ROM drive on the disc and tapes down the lid switch.

Cleaning

Retrostuff's laser sledge guide assumes that the lens has been cleaned and the fault diagnosed in the Service Shell before any parts are changed. The Magnavox manual's advice for a distorted picture or a disc that will not start is to clean the disc with a soft cloth from the centre outwards, and to check that the disc cover is properly closed.

CDM 12.1T mechanism

The CDI 450 uses the top-loading CDM 12.1T (Philips code 4822 691 30343), which has an ornamental plate and shorter wires than the tray-loading CDM 12.1. Replacement VAM 1201 and VAM 1202 assemblies come without the plate and with wires that are too long or missing, so retrostuff replaces only the laser sledge on top-loading players.

Cleaning and regreasing

Retrostuff's procedure for a CDM 12.1T that gives dirty-disc messages or stutters, summarised from its sledge replacement guide:

1. Ground yourself. Unplug the mechanism from the main panel and slide out the four rubber suspensions one at a time with a blunt tool. The rubber is soft and cuts easily.
2. Turn the mechanism over without pressing on the spindle motor, or you will push the turntable down.
3. Move the sledge to the end of its travel, either with ARM OUT in the Service Shell or by turning the worm gear on the sledge motor by hand. Lift off the gearwheel.
4. Note the wire routing, then remove the limit switch (Torx T6) and push out the two plastic wedges that hold the steel rod. Lift out the rod with the sledge.
5. Soak the gearwheel, rod and wedges in isopropyl alcohol and clean the old grease from the worm gear and the guides. Do not remove the sledge motor, which is glued to the case.
6. Refit the rod and sledge, and grease the steel rod, the guide at the opposite end, the worm gear and the gear rack or small gearwheel. Retrostuff used a PTFE-based grease.
7. Spread the grease with ARM IN and ARM OUT in the Service Shell, or by playing an audio CD and skipping between tracks.
8. Refit the suspensions, starting at the upper left corner and working anticlockwise, with the wires routed as before.

Turntable height

If the spindle motor struggles to reach speed after work on the mechanism, the turntable has probably been pushed down. Lever it up evenly with a flat tool until the disc runs clear of the case with the lid closed. Retrostuff then put a drop of threadlocker on the top of the spindle and left it to cure for 24 hours.

NVRAM timekeeper

The CDI 450 stores its settings, saved games and the clock in an 8 KB timekeeper chip, position 7241, listed as an MK48T08B15. Its 8K x 8 SRAM holds the CSD (configuration status description) and FTS files. The chip carries its own BR1225 lithium cell. Once the oscillator has been started the cell runs down, and after some years the player loses its data and date, or stops at a light blue screen or a "memory full" error. A date that has fallen back to 1989 is a sign of a failed timekeeper. The CDI 450 and CDI 550 that retrostuff opened had the newer M48T08-150PC1, which has its crystal and battery in a capped housing.

Replacing the chip

• Remove the system ROM first if it is socketed, or desolder it, to reach the timekeeper. Desolder with fresh solder, plenty of flux and a desoldering gun; some pins are soldered on both sides.
• A socket raises the chip into the metal cage of a top-loading player. Retrostuff no longer recommends socketing it in a CDI 450.
• Direct replacements: the STMicroelectronics M48T08-150PC1, still made and sold by distributors such as Mouser, and the Dallas DS1643, which is compatible but out of production. Retrostuff warns against "new" timekeepers from eBay or AliExpress.
• The old MK48T08B can be repaired by removing its top hat and fitting a new battery, or a replacement top hat such as the Glitch Works GW-48T08-1 or CabriDIY's TimeKeeper board.

The 8 KB timekeeper and the 32 KB SmartWatch solution used in other players are not interchangeable. A 32 KB upgrade on the CDI 450 needs two extra address wires, the removal of resistor 3241 and a patched system ROM. A DS1216C socket with an SRAM on top is too tall for the cage even when soldered directly to the board; a DS1244Y fits only when it is soldered straight in.

Calibrating the clock

Item 7 of the Low Level Test trims the timekeeper so that it keeps time to within one minute a month. It needs a frequency counter: measure the 512 Hz signal on pin 25 of the CIAP (IC 7310, signal CSCIAPN) with a gate time of at least 5 seconds, then enter the reading. The expected range is 511.96724 to 512.03276 Hz. Philips says not to run this step unless calibration is needed; if it is entered by mistake, switch off and restart the test. Retrostuff advises calibrating after replacing or repairing a timekeeper, especially when the old crystal has been reused. The Dallas DS1643 ignores calibration data.

External power supply

The 20PS301 (22ER9156) supply plugs into DC IN on the back of the player through an RJ45 (8P8C) plug. Retrostuff reports that these supplies almost never need servicing; the usual problems are a broken locking tab on the plug and a missing supply.

20PS301 output plug (RJ45)

RJ45 pin	Wire (PSU)	Signal
1	0202 red	+5 V
2	0201 white	Sense / +5 V
3	0203 red	+5 V
4	0205 black	Ground
5	0204 red	+5 V
6	0206 black	Ground
7	0207 green	-5 V
8	0208 grey	ON/OFF

• A plug with a broken tab still works but can be pulled out by accident. Cut it off and crimp a new 8P8C plug, or fit a clip-on tab repair.
• The case screws under the rubber feet are one-way screws. Retrostuff drilled two small holes in each so that a spanner screwdriver could turn them.
• The fuses are 1101 (T500 mA L 250 V glass, mains), 1201 and 1203 (MP400, +5 V) and 1202 (MP400, -5 V). The UK version has a 3 A fuse in its BS 1363 plug.
• The US version (/17) has a 10 MΩ resistor, 3102, from neutral to ground, marked "Use only in UL/CSA Version" on the circuit diagram.

Substitute supplies

The player needs +5 V at 3.3 A and -5 V at 0.25 A, and switches the supply by pulling pin 8 to ground. An arcade supply with both voltages works but leaves the player's power button inert. An ATX 1.x supply can be wired with -5 V from its pin 18 and PS_ON from its pin 14 to RJ45 pin 8. Retrostuff also lists Jeff Chen's adapter for two ordinary +5 V supplies and zaxour's G2 supply, which needs a single DC input.

Whatever the source, keep to the pin numbering above and use a separate conductor for every +5 V and ground pin; retrostuff warns that a mistake here will damage the player. Check +5 V, -5 V, ground and PS_ON on an ATX supply before connecting it, because ATX wiring is not always standard.

Preventive maintenance checklist

1. Check the date and time in the player shell. A year of 1989 or a lost date points to the timekeeper.
2. Inspect the RJ45 plug and its tab, and the cable where it leaves the supply.
3. Clean the lens and check that the disc spins up quietly and reads without dirty-disc messages.
4. Run the Service Shell CD drive test (modes 0 to 3) if discs read unreliably.
5. Measure +5 V and -5 V at the plug under load, as described on the troubleshooting guide.

Related pages

• Philips CDI 450
• Philips CDI 450 Troubleshooting Guide
• Philips CDI 450 Capacitor Replacement Guide
• Philips CDI 450 Documentation
• Battery Explosion, Capacitor or Corrosion Damage
• Recommended Tools