GI CFT-2000 and CFT-2100

These analog cable receivers were commonly used in the UK market, by several cable operators. I know of several models which were used here:

• iDPBB7000: Also known as the “Intercon 7000 Impulse”, branded as the Jerrold 550.
• iCFT2000: iCFT 2026/210.
  • Approx. May 1995 vintage.
• CFT2100: CFT2143/102/RC/UK/A seems to be the model most commonly deployed in the UK.
  • Approx. 1999 vintage.
  • Branded as “General Instrument” – the Jerrold branding is completely omitted from these units.
  • Known to have been used by NTL in various regions, and Milton Keynes Cable (MK Cable).

• Main CPU: Custom GI part

  • (STMicroelectronics logo)
    CTTEBSSL-00
    404291-002-69
    (C) WDC 1984
    (C) GIC 1996
    A22BC9836
    MALTA

  • W65C02S core, possibly in the form of a custom ASIC (like the BSB ACM) (see this usbjtag thread)
• System ROM: 27C512, encrypted (encryption is trivial 2-stage XOR, based on address bus and fixed key table)
• System RAM: Sanyo LC3564BM-10, 64kbit (8K * 8)
• There is likely some battery-backed RAM on the CPU
• An earlier version of this IC (GIC branded) from the US-model DPBB7000 carries the text “CamelBack” on the die.
  • This ties in with “CamelBack” on the model number decoder: CamelBack is likely the codename for the processor

The display board carries:

• An infrared receiver
• Two Liteon LTD-6910HR dual 7-segment common-anode LED displays
  • The left display is mounted with the decimal points at the top
  • The right display is mounted with the decimal points at the bottom
• A 74LS164 shift register (likely to drive the segment cathodes)
• Several driver transistors (four of these are likely for the common anodes)

The interface to the motherboard consists of:

• Display 1,2,3,4 drive enable (4 pins)
• Clock and data to 74LS164
• Infrared signal to main PCB

TODO: Segment to data bit map, pinout, schematic

These boxes can suffer from two main faults:

• Bad soldering on the large PSU capacitors (front left of PCB)
  • Manifests as the box rebooting when it's moved or bumped.
• Bad capacitors
  • Bad capacitors near the tuner cans and video decoders will cause the OSD to jitter or be unreadable.
  • Best option is a full re-cap.

They also suffer from the standard Jerrold issue of channel names being scrambled (usually square blocks), channels failing to tune, the box ignoring the remote control, and general misbehaviour. If this happens, it's a sure sign that the nonvolatile memory backup battery has run flat. The fix is to replace the battery, remove any installed modchips (or at least make sure they're powered from the 5V supply instead of the battery-backed supply), and Reinitialize the box.

If the box ignores the remote control and shows error code EA, the serial number has become corrupt. There is no known way to recover a box from this state.

The following US Patents are listed on the bottom of the unit.

• US4476584A: Digital frequency lock tuning system, Charles L. Dages
  • PLL tuning for a cable box
• US4546387: Circuit for providing accurately spaced video and sound carriers, Joseph B. Glaab
  • Using two PLLs to generate video and sound carrier signals
• US4575755A: Video encoder/decoder system, Carl F. Schoeneberger, Allan B. Bundens, Richard A. Blake, Richard M. Fogle. (Tocom)
  • Tocom video scrambling system
• US4621285A: Protected television signal distribution system, John Schilling, Joseph Dolinski
  • Tagging and GI/Jerrold “RF” scrambling scheme
• US4558464A: Address-programmable CATV converter, Thomas E. O'Brien, Jr.
  • FSK out-of-band signalling channel and activation/initialisation commands
• US4603349A: Cable television system with stereo sound reproduction
  • Modifications to sync-suppression scrambling to allow its use with Zenith-DBX stereo sound
    • The dbx-TV companding system for multichannel TV sound (NAB Proceedings 1984)
    • A technical overview of the Zenith/dbx Stereo Television Transmission System
  • SAP: “Subsidiary audio programme”