Philips CDI470 Diagnosis and Repair

Philips CDI470 Diagnosis and Repair

For upcoming experiments, I was in need of a working CD-i player with a Mono IV mainboard and 8 KB of NVRAM. I checked my basement and found a broken CDI470/20 that had been sitting there for years. Previous repair attempts had failed and I hadn’t bothered to look at it since.

Upon the first start, it greeted me with the memory full error:

CD-i memory full error
CD-i memory full error

NVRAM repair

This is a well-known error for CD-i players, usually an indication of a broken TimeKeeper (NVRAM) chip. However, I already fitted a socket and a new DS1643 chip years ago and it was still displaying the error. Back then, I suspected it to have a broken mainboard and banished it to my basement.

The error didn’t go away after fitting various DS1643 and M48T08 chips, and also the low-level test via serial terminal reported a problem:

Low-level test: NVRAM error
Low-level test: NVRAM error

I took a closer look at the service manual and the solder joints of the socket and checked the traces with a continuity tester. It turned out that pin 11 (D8NVR!) didn’t have a proper connection with the mainboard.

NVRAM socket solder joints
NVRAM socket solder joints

I renewed the solder joints of all pins of the socket which seemed to make the memory error go away.

Low-level test: NVRAM OK
Low-level test: NVRAM OK

Unfortunately, it came back after a while (and some NVRAM tests which will be featured in another article). To fix the error for good, I connected pin 11 with a short piece of wire to the next test point (close to resistor 3249; not pictured here).

Service Shell

For further experiments, I also needed the player to be able to actually play some games. The discs, however, didn’t want to spin at all. I inserted a test plug to boot the player into the Service Shell.

CD-i Service Shell
CD-i Service Shell

To start the disc drive test, insert an Audio CD (a CD-i game is also fine, by the way) and click the button CD PLAYER. Oh, and don’t look into the laser!

In Mode 0, be careful with the SLEDGE OUT and SLEDGE IN commands. Only click them once and/or alternatingly. Otherwise, the sledge with the laser will try to go beyond limits and possibly damage the gear racks.

Service Shell: Mode 0
Service Shell: Mode 0

This is what SLEDGE OUT and SLEDGE IN do:

Press NEXT MODE for the focus test (Mode 1). IN FOCUS is a good result, the laser is able to see the disc:

Service Shell: Mode 1 (IN FOCUS)
Service Shell: Mode 1 (IN FOCUS)

Press NEXT MODE for the motor test (Mode 2). MOTOR ERROR is a bad result, obviously, and means that we have found a problem: The motor isn’t able to spin, for whatever reason. The test sequence jumps back to Mode 0.

Service Shell: Mode 2 (MOTOR ERROR)
Service Shell: Mode 2 (MOTOR ERROR)

Motor repair

The world of CD-i has a tutorial to repair similar errors. I started with solution 4: It advises to lift the spindle up with a flat tool.

CD tray loader - spindle
CD tray loader – spindle

For easier access, I removed the whole assembly (CDM 12.1) by pushing the four rubber suspensions (yellow circles) through the holes.
Important: Take notes or pictures of the routing (red squares) before releasing the wires.
Alternative: Desolder the six wires, especially if you want to replace the assembly anyways (see Plan B below).

CD tray loader - cable routing
CD tray loader – cable routing

A first test after lifting the spindle. This is a delicate setup and must not be run without supervision. As soon as the sledge moves, the whole assembly will move around as well!

Playing a CD without tray loader
Playing a CD without tray loader

Still, this setup was sufficient to pass the tests successfully:
Mode 2 (TURN MOTOR OK) and Mode 3 (RADIAL TEST OK).

Clicking on NEXT MODE resets the CD-i player and starts the disc in the regular player shell. I recommend using Burn:Cycle for this test, as it reads a lot of data and moves the laser back and forth during the demo and intro animations.

Because of the delicate setup above, all I got was the dirty disc message:

CD-i dirty disc error
CD-i dirty disc error

Very carefully, I picked up the assembly (with the spinning disc) and held it in my hand for a couple of minutes. The demo and intro animations played fine this time.

Before I put everything back together, I applied some grease on the gears and the metal rod that the sledge sits on. The SLEDGE OUT and SLEDGE IN commands help with spreading the grease.
Next, I aligned the assembly as shown in the picture below and re-attached the rubber suspensions one by one.
Then, I routed all cables as they were before and plugged them back into the mainboard.

CD tray loader and CDM assembly aligned
CD tray loader and CDM assembly aligned

Plan B

Just in case, e.g. if lifting the spindle didn’t work or if the laser turned out to be too weak, I had a replacement assembly ready.

Philips CDM 12.1 and VAM 1202
Philips CDM 12.1 and VAM 1202

The Philips VAM 1202 is the official substitute part for the CDM 12.1 that you can still buy these days. The only parts that are missing are the four rubber suspensions and the six wires. You will have to move them from the old to the new assembly if you plan replace the whole thing.

Philips CDM 12.1 and VAM 1202 (back)
Philips CDM 12.1 and VAM 1202 (back)

Conclusion

After all, the errors turned out to be easily fixable. Philips CDI470 Diagnosis and Repair is there to show you that a proper diagnosis is the most important part of a repair.

The Service Shell is a great tool that helps to diagnose various errors. It is usually started by using a dummy/test plug or by connecting pins 2 and 3 of the front controller port. As it differs slightly from player to player, explanations for all tests can be found in the corresponding service manual. (Initially, I had planned to handle this topic in this unfished article, but now it ended up here.)

This is hidden behind the buttons that we haven’t pressed yet:

Service Shell: TEST IMAGE
Service Shell: TEST IMAGE
Service Shell: EXIT
Service Shell: EXIT

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