This second part continues the documentation of the Philips CDI 310 EMC/EMI Testing Unit with a detailed examination of the mainboard and the system ROM. It focuses on the electrical differences compared with the CDI 350, including removed components, altered circuits, and other modifications. If you have not read the teardown yet, you can find it in Part 1.
Originally being a CDI 350 mainboard, several components are not required in a CDI 310 — particularly those associated with the missing display and speakers. In addition to parts that were removed or replaced, many solder joints have been manually reworked, including most connectors and ground points.
- Differences between 310 and 350 mainboards
- Comparison with a regular 310 mainboard
- System ROM
- Conclusion
- Credits
- History
Differences between 310 and 350 mainboards
To document the changes, I placed both mainboards side by side. Since I did not have an unaltered CDI 350 mainboard at hand, the board shown on the left has already been reworked according to my repair article. I chose one with a yellow silkscreen for easier comparison.
Each section was then examined individually, with differences first marked on printed schematics and later transferred into tables. Components are tagged with grid coordinates from the CDI 350 service manual. For orientation, two grid systems are used: the mainboard grid (Grid 1) and the section‑specific grids (Grid 2) found in schematic blocks such as Audio 2, Video 1, MMC 3, etc. Board sides (top = A, bottom = B) are also indicated. The sections do not follow the order of the service manual. I’ve added some comments as well, for example which functions or other components are affected.
Why go to all this trouble? Quite simply, I still have extensive work ahead removing the leaking SMD electrolytics and cleaning the board. When fitting new components to get the 310 working again, I can rely even less on the 350 service manual. These tables will be updated as further findings emerge during repair.
Power
Two of the Video 1 power rails — +5L and –8L, originally used for the LCD panel — have been taken out of service. The fuse for +12B Video 1 (LCD backlight) has been replaced, and this rail is now repurposed to supply +12 V to the FDD controller.
One interesting detail I’ll have to investigate during repair: the fusible component LP03 has been bridged. This suggests it may have blown during testing or while the speaker amplifier and related circuits were being removed.
Schematics reference: 6.4.4 Power/Audio Schematic Diagram (Part 2)
| ID | Side | Grid1 | Grid2 | Status | Notes |
|---|---|---|---|---|---|
| CP14 | A | B11 | A4 | removed | +5L Video 1 |
| CP15 | A | B10 | A5 | removed | +5L Video 1 |
| CP16 | A | B10 | A5 | removed | +5L Video 1 |
| CP25 | A | B10 | C4 | removed | -8L Video 1 |
| CP26 | A | D11 | C4 | removed | -8L Video1 |
| CP27 | A | C11 | C5 | removed | -8L Video 1 |
| CP28 | B | C2 | C5 | removed | -8L Video 1 |
| FP02 | A | B10 | B3 | replaced | +12B Video 1 |
| ICP3 | A | C10 | C4 | removed | -8L Video 1 |
| ICP4 | B | B2 | A4 | removed | +5L Video 1 |
| LP03 | A | C11 | D4 | bridged | -8A Audio 1,2 |
| QP01 | B | C2 | B5 | reworked | +10A Audio 1,2 |
| RP09 | B | B2 | A3 | removed | +5L Video 1 |
Audio 2
Almost all components of the speaker amplifier have been removed. The entire audio output path for the internal speakers is gone, although the speaker connector — and a handful of passive SMD parts — remain in place.
Schematics reference: 6.4.4 Power/Audio Schematic Diagram (Part 2)
| ID | Side | Grid1 | Grid2 | Status | Notes |
|---|---|---|---|---|---|
| C526 | A | H1 | A15 | removed | Speaker Amp |
| C527 | A | H1 | A15 | removed | Speaker Amp |
| C530 | A | H1 | C15 | removed | Speaker Amp |
| C532 | A | H2 | B15 | removed | Speaker Amp |
| C537 | A | G2 | B16 | removed | Speaker Amp |
| C538 | A | H2 | C16 | removed | Speaker Amp |
| C541 | A | H1 | B13 | removed | Speaker Amp |
| C543 | A | G1 | B16 | removed | Speaker Amp |
| C546 | A | I1 | B14 | removed | Speaker Amp |
| C547 | A | H1 | B15 | removed | Speaker Amp |
| D553 | B | H12 | B13 | removed | Speaker Amp |
| IC60 | A | H1 | B15 | removed | Speaker Amp |
| IC61 | B | H11 | B15 | removed | Speaker Amp |
| L502 | A | I6 | A16 | reworked | Audio L Out |
| L503 | A | I2 | E17 | reworked | Headphone R Out |
| L504 | A | I4 | E17 | reworked | Headphone L Out |
| Q517 | B | I12 | B14 | removed | Speaker Amp |
| Q518 | B | H12 | C14 | removed | Speaker Amp |
| R522 | B | H10 | C16 | removed | Speaker Amp |
| R524 | B | G11 | B16 | removed | Speaker Amp |
| R533 | B | I11 | C14 | removed | Speaker Amp |
| R534 | B | H11 | C14 | removed | Speaker Amp |
| R543 | A | I1 | B14 | removed | Speaker Amp |
| R544 | B | G10 | B16 | removed | Speaker Amp |
| R545 | B | H11 | C14 | removed | Speaker Amp |
| R546 | B | H10 | C16 | removed | Speaker Amp |
| R548 | A | I1 | B14 | removed | Speaker Amp |
| R549 | B | H12 | C14 | removed | Speaker Amp |
| R576 | B | H12 | B14 | removed | Speaker Amp |
| R577 | B | H12 | B14 | removed | Speaker Amp |
| R578 | B | H12 | B14 | removed | Speaker Amp |
Video 1
Most of the changes relate to connector J402, to which the FFC for the LCD is connected on the 350. On the 310, the FDD controller is connected there instead, and naturally it does not require any video signals. Components responsible for switching between internal and external video, brightness control, and other display-related functions have been removed entirely.
Basically, the original purpose of J402 has become obsolete or has been reconfigured. It now supplies the FDD controller with +12 V.
Schematics reference: 6.4.5 Video Schematic Diagram (Part 1)
| ID | Side | Grid1 | Grid2 | Status | Notes |
|---|---|---|---|---|---|
| C451 | A | E9 | C8 | replaced? | J402 pin 21 DISPC and pin 24 GNDB |
| C453 | A | G8 | B7 | replaced | From +5L to J402 pin 11+24 |
| C454 | A | G8 | A7 | replaced | J402 pin 5 -8VL to GND |
| C455 | B | F4 | A7 | replaced? | J402 pin 14 VSW to GND |
| C456 | B | F4 | C3 | replaced? | J402 pin 12 VCDC to GND |
| C457 | A | G8 | B7 | removed | From +5L to J402 pin 11+24 |
| C458 | A | G8 | A7 | removed | From -8L to GND |
| C461 | B | G5 | A3 | removed | IC48 / +5L to GND |
| C462 | A | E9 | E7 | replaced? | J402 pin 9 BRT (Brightness) to GND |
| IC48 | B | G5 | B3 | removed | Switches CS int/ext – to J402 pin 10 CS |
| J993 | B | D4 | C7 | removed | HSLCD and VSLCD – to J402 pins 19 VS and 20 HS |
| L451 | A | F9 | D8 | removed | J402 pin 8 RTU (Video signal from J404) |
| L452 | B | F4 | D8 | removed | J402 pin 7 – GTU (Video signal from J404) |
| L453 | B | F4 | D8 | removed | J402 pin 6 – BTU (Video signal from J404) |
| L454 | A | F8 | D8 | replaced? | J402 pin 4 RCDI (Video signal from VSD) |
| L455 | A | F8 | D8 | replaced? | J402 pin 3 – GCDI (Video signal from VSD) |
| L456 | A | F8 | D8 | replaced? | J402 pin 2 – BCDI (Video signal from VSD) |
| L457 | B | F4 | C3 | removed | from ext SW to J402 pin 14 VSW |
| L458 | A | G7 | B7 | removed | From +5L to J402 pin 11+24 +5L |
| L459 | A | G8 | A7 | removed | From -8L tp J402 pin 5 -8VL |
| R450 | B | G4 | B2 | removed | IC48 / CS input |
| R451 | B | G5 | B2 | removed | IC48 / GND to input |
| R452 | B | G4 | B2 | removed | IC48 / GND to input |
| R457 | A | G7 | E7 | replaced | Between GND and J402 pin 4 RCDI |
| R458 | A | G7 | E8 | replaced | Between GND and J402 pin 3 GCDI |
| R459 | A | G7 | E9 | replaced | Between GND and J402 pin 2 BCDI |
| R472 | B | I4 | E6 | removed | Between +5L and RV41 |
| R473 | B | I4 | E6 | removed | Between GND and RV41 |
| R478 | B | F4 | B4 | removed | To J402 pin 10 CS |
| R479 | B | F4 | n/a | populated | ? |
| R481 | A | G8 | A7 | removed | From -8L to RV42 |
| R482 | A | E9 | C7 | removed | J402 pin 21 DISPC |
| RV41 | A | H9 | E6 | removed | From +5L & GND to J402 pin 9 BRT (Brightness) |
| RV42 | A | G8 | A7 | removed | From -8L & +5L to J402 pin12 VCDC |
Miscellaneous
Additional changes appear across several sections. The DISPC components, which control display on/off switching in MMC 3, are absent. In MMC 1 and MMC 3, clock signal pins of the VSD, VSC and CPU have been lifted and reattached. The VSD still carries a small SMD capacitor (likely around 1 pF) between the lifted pin and the mainboard.
Several other components show visible rework. I have listed the most relevant ones in the table, although not every single re‑soldered part is included — there are simply too many minor touch‑ups to document individually. The purpose of some of the modifications is not entirely clear, but they suggest that tests were carried out during pre-production and EMC/EMI evaluation in which certain functions were disabled, bypassed or temporarily deactivated.
Below are a few selected photos of these changes; additional examples can be found in the earlier sections.
Schematics references:
6.4.3 Audio Schematic Diagram (Part 1)
6.4.7 MMC Schematic Diagram (Part 1)
6.4.9 MMC Schematic Diagram (Part 3)
6.4.2 Servo Schematic Diagram
6.4.6 Video Schematic Diagram (Part 2)
| ID | Side | Grid1 | Section | Grid2 | Status | Notes |
|---|---|---|---|---|---|---|
| C726 | A | G10 | Audio 1 | D7 | replaced? | Filter IC71 |
| C727 | A | G10 | Audio 1 | D7 | replaced? | Filter IC72 |
| C732 | A | H10 | Audio 1 | B7 | replaced? | Filter IC72 |
| C741 | A | G10 | Audio 1 | D7 | replaced? | Filter IC71 |
| C742 | A | H10 | Audio 1 | B7 | replaced? | Filter IC72 |
| C435 | A | E4 | MMC 1 | B10 | replaced? | From +5R to VSD pin 81 VDD2 |
| IC40 | B | B4 | MMC 1 | B4 | pin lifted | VSC pin 119 XTAL1 |
| IC42 | B | B6 | MMC 1 | B2 | pin lifted | VSC pin 119 XTAL1 |
| IC44 | B | D8 | MMC 1 | B9 | pin lifted | VSD pin 55 XT2 |
| L401 | A | E6 | MMC 1 | A10 | reworked | From +5R to VSD pin 81 VDD2 |
| C107 | A | F8 | MMC 3 | F13 | removed | SYSCLK to CPU |
| C108 | A | F8 | MMC 3 | G13 | removed | SYSCLK to FMV |
| C109 | A | F8 | MMC 3 | G13 | removed | SYSCLK to VSC |
| IC01 | A | C7 | MMC 3 | B9 | pin lifted | SCC pin 30 XTAL_1 / SYSCLK |
| QF04 | B | F8 | MMC 3 | E4 | removed | DISPC |
| R119 | A | F8 | MMC 3 | F13 | replaced | SYSCLK to CPU |
| R120 | A | F8 | MMC 3 | G13 | replaced | SYSCLK to FMV |
| R121 | A | F8 | MMC 3 | G13 | replaced | SYSCLK to VSC |
| RF19 | B | F8 | MMC 3 | E4 | removed | DISPC |
| RF20 | B | F9 | MMC 3 | E4 | removed | DISPC |
| RF21 | B | F8 | MMC 3 | E5 | removed | DISPC |
| SWF1 | A | I8 | MMC 3 | B1 | removed | Signal KEY03, KEY13 (Display on/off) |
| X101 | B | C4 | MMC 3 | E9 | reworked | SCC68070 |
| C811 | B | A11 | Servo | B4 | replaced? | Between +5S and IC80 |
| C814 | B | C11 | Servo | B5 | replaced? | Between IC80 and IC82 |
| C821 | B | C10 | Servo | E3 | replaced? | Between REF and IC81 |
| C822 | B | C10 | Servo | E3 | replaced? | Between REF and IC81 |
| L904 | B | I6 | Video 2 | C15 | reworked | CVBS OUT |
| L905 | B | I7 | Video 2 | D15 | reworked | Y OUT |
| L906 | B | I8 | Video 2 | F15 | reworked | C OUT |
| R973 | B | F11 | Video 2? | n/a | replaced | next to IC93 |
Comparison with a regular 310 mainboard
Here is a photo of a regular CDI 310 main chassis (courtesy of CD-i Fan); the mainboard fitted to it has a white silkscreen. No subsequent soldering work is visible, and it was in fact manufactured without the missing components listed above. On closer inspection, further components are absent as well, such as R532 from the speaker amplifier and C459/C460 from the Video 1 section — which makes sense, as these components belong to circuits that have been completely removed.
Although this comparison is useful, it is based on a single photo of a regular CDI 310 mainboard. A thorough examination of a standard production unit — ideally from all sides and with detailed close‑ups — would be valuable whenever the opportunity arises. It would help confirm which components were never fitted on the 310, which differences are consistent across units, and which may vary between production batches.
System ROM
And finally, a look at the pre-release system ROM R1.1, which carries a handwritten sticker with the date 93-7-10 and checksum B706. Since the serial connection with CD-i Link could not be established, the IC had to be desoldered and dumped the old-fashioned way using an EPROM burner. It’s a Toshiba TC544200F-150 OTP ROM, which can be read using a TC574200D or 27C400 driver.
According to CD-i Fan, the only difference compared with the regular CDI 310 system ROM (cdi310a12) is a missing shell module.
Modules and checksums:
Addr Size Owner Perm Type Revs Ed # Crc Module name
-------- -------- ----------- ---- ---- ---- ----- ------ ------------
00003cea 26650 0.0 0555 Sys a000 83 090798 kernel
0000a504 18082 10.48 0555 Trap c00a 6 5f673d cio
0000eba6 2992 0.0 0555 Data 8020 1 191a59 FONT8X8
0000f756 2270 0.0 0555 Fman a000 35 d6a976 pipeman
00010034 5592 0.0 0555 Fman a000 17 63023d nrf
0001160c 2848 0.0 0555 Fman a00b 35 28611f ucm
0001212c 4510 0.0 0555 Fman a003 96 a4d145 cdfm
000132ca 1934 0.0 0555 Fman a000 31 b41f17 scf
00013a58 7798 1.0 0555 Trap c001 13 46c5dc math
000158ce 8952 0.0 0555 Fman e000 79 f098af rbf
00017bc6 18310 0.0 0555 Fman a001 70 3d85d6 pcf
0001c34c 256 0.0 0113 Data 8000 1 1b61fb copyright
0001c44c 416 0.0 0555 Prog 8007 7 300458 sysgo
0001c5ec 338 0.0 0555 Sys 8000 22 bfd362 init
0001c73e 120 0.0 0555 Desc 8000 6 7fc9e7 t2
0001c7b6 1598 0.0 0555 Driv a024 18 1355e6 u68070
0001cdf4 550 0.0 0555 Sys a000 2 638259 sgstom
0001d01a 136 0.0 0555 Desc 8000 1 129ccc tim070
0001d0a2 276 0.0 0555 Driv a006 3 629926 tim070driv
0001d1b6 118 0.0 0555 Desc 8000 2 da7d37 nil
0001d22c 172 0.0 0555 Driv a000 1 407f81 null
0001d2d8 102 0.0 0555 Desc 8000 2 cf450e pipe
0001d33e 774 0.0 0555 Driv a001 6 b95594 nvdrv
0001d644 94 0.0 0555 Desc 8000 1 a45d20 nvr
0001d6a2 66698 0.0 0555 Driv a012 48 697b6b video
0002db2c 130 0.0 0555 Desc 8000 1 2352c6 vid
0002dbae 130 0.0 0555 Desc 8000 1 07c5da vd2
0002dc30 134 0.0 0555 Desc 8000 1 3cb345 vdk
0002dcb6 132 0.0 0555 Desc 8000 1 f07544 v12
0002dd3a 132 0.0 0555 Desc 8000 1 b4d137 v96
0002ddbe 1130 0.0 0555 Driv a010 8 90e654 msuart
0002e228 130 0.0 0555 Desc 8000 1 6585dd pt2
0002e2aa 918 0.0 0555 Driv a002 3 643ad4 gtuart
0002e640 136 0.0 0555 Desc 8000 1 26bdd3 gt12
0002e6c8 136 0.0 0555 Desc 8000 1 e4dd66 gt96
0002e750 322 0.0 0555 Driv a004 2 4f2bba ckeydriv
0002e892 132 0.0 0555 Desc 8000 1 bc1dbb ckey
0002e916 1838 0.0 0555 Driv a00e 7 0ce60c pck2driv
0002f044 138 0.0 0555 Desc 8000 1 1b4919 pck2
0002f0ce 1552 0.0 0555 Driv a002 1 83a85e kb1driv
0002f6de 134 0.0 0555 Desc 8000 1 dd01fa kb1
0002f764 18236 0.0 0555 Driv a038 28 fdc699 cdapdriv
00033ea0 136 0.0 0555 Desc 8000 1 a37054 cd
00033f28 136 0.0 0555 Desc 8000 1 e2292a ap
00033fb0 192 0.0 0777 5 8001 1 8c38ad csd_360
00034070 5482 0.0 0555 Sys a000 29 2aca6a csdinit
000355da 8344 0.0 0555 Prog 8001 9 7d87fe config
00037672 1748 0.0 0555 Driv a000 2 aac65d kbdrvr
00037d46 128 0.0 0555 Desc 8000 1 ad4f2a kb
00037dc6 826 0.0 0555 Driv a010 8 fb6f38 pointer
00038100 128 0.0 0555 Desc 8000 1 1338ca ptr
00038180 1948 0.0 0555 Driv a00a 5 aefc10 sldriv
0003891c 130 0.0 0555 Desc 8000 1 b6426f slave
0003899e 136 0.0 0555 Prog 8000 1 15b936 chkflop
00038a26 2604 0.0 0555 Driv a008 8 3dbc02 rb765
00039452 138 0.0 0555 Desc 8000 2 d0b468 dd
000394dc 138 0.0 0555 Desc 8000 2 55f519 d0
00039566 140 0.0 0555 Desc 8000 2 11a00a d0tb
000395f2 138 0.0 0555 Desc 8000 2 321e19 d0h
0003967c 140 0.0 0555 Desc 8000 2 89aaf8 d0hd
00039708 140 0.0 0555 Desc 8000 2 0f58e8 d0uv
00039794 140 0.0 0555 Desc 8000 7 23730b pcd0
00039820 140 0.0 0555 Desc 8000 7 5407a3 pcd0h
000398ac 22114 0.0 0555 Prog 8003 8 8d41e0 sv
0003ef0e 8150 0.0 0555 Prog 8007 7 7dd424 launcher
00040ee4 3932 1.0 0777 Data 8001 1 d16d98 upslbd11.ai1
00041e40 3772 1.0 0777 Data 8001 1 3acf59 rhobd10.ai1
00042cfc 2576 1.0 0777 Data 8001 1 765760 sigmbc7.ai1
0004370c 2996 1.0 0777 Data 8001 1 09927f upslbd10.ai1
000442c0 5964 1.0 0777 Data 8001 1 83e9c2 genevas11.fnt
00045a0c 19104 0.0 0113 Data 8004 1 42e07a audiocd
0004a4ac 18624 0.0 0113 Data 8005 1 a05107 dsett319
0004ed6c 13536 0.0 0113 Data 8000 1 38793a dmem319x
0005224c 33102 0.0 0555 Prog 8036 9 80a0f7 cdgrj
0005a39a 18304 0.0 0113 Data 8013 1 e4d6fc phil
0005eb1a 96792 0.0 0555 Prog 8036 9 565fe7 play
00076532 38592 0.0 0113 Data 8000 1 931f80 dummy
File Addr Size Type Description
------------------ -------- ------ ------------------ ------------
cdi310a11.rom 00000000 512K cdi310a11.rom Philips CD-i 310 system ROM 1.1
cdi310a11.rom 00000000 512K cdi310a.mdl Philips CD-i 310 player
cdi310a11.rom 00000000 512K minimmc.brd Mini-MMC board
cdi310a11.rom 00000000 511K cdi310a11.tag {511K} ID: 51 Rel: 11 Sum: B706
cdi310a11.rom 00000000 512K cdi310a11.crc CRC: 96DB66AB
cdi310a11.rom 00000000 512K cdi310a11.md5 MD5: 3332BA7D81290C2132193FC406BE81D5Conclusion
This concludes the first two parts in a series of articles on the Philips CDI 310 EMC/EMI Testing Unit. All major assemblies have now been taken apart and documented, including the mainboard, FDD controller and system ROM.
Although very few people will ever have the opportunity to repair a CDI 310, the tables listing removed and modified components may still be useful for converting a CDI 350 with a faulty display into a fully functional unit without a display.
The next article(s) will focus on repair work, capacitor replacement and the practical operation of this unit.
Credits
Many thanks to CD-i Fan for providing information and photos of a regular CDI 310 model, as well as analysis of the system ROM.
History
2026-09-02: Initial version published
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