BSB DMAC receivers and modifications

Receiver DataVision (data port) AGB Audience Survey D2MAC mod? Notes
Ferguson SRB1 :?: Modified for D2MAC and PAL reception by Trac Satellite and others.
Tatung TRX2801
(Decca DRX-2851)
:?: Data port is present but used for AGB Audience Survey. DataVision not expected to be implemented.
Philips STU902 :?: Manual suggests that the data port “may be used for features such as an Audience Survey”
ITT-Nokia/Salora 5903 :?: :?: :?:

DataVision support is speculative - it's not known whether this was actually deployed by BSB. An article in New Scientist from January 1990 (BSB faces setback over business data service) says that Ferguson “had been burning midnight oil to write the software needed to decode Datavision, and [believed] it was ahead of its three competitors, Philips, Salora and Tatung.”

A BSB Datavision promo video is available on Youtube.

Ferguson documentation:

The SRB1 was the 'standard' BSB receiver at launch, and proved to be very versatile. After BSB's closure, many of these were sold at a low price as liquidated stock and modified to receive other satellite signals. Trac Satellite were a key player in this market, producing several modification kits ranging from a simple D2MAC FTA ROM-swap to a full dual-mode PAL/D2MAC conversion with a Eurocrypt smartcard slot and built-in “two-chip” Multimac smartcard.

I don't know what the difference between the various Trac Satellite ROMs is, or how to identify the modifications. If you know, please drop me an email: philpem@gmail.com.

“s-band” uploaded the manual for the D2MAC Mod EPROM to Satellites.co.uk: https://www.satellites.co.uk/forums/threads/trac-satellite-d2mac-mod-instructions.178510/

Temporarily reverting the PAL/DMAC mod

The PAL/DMAC modification can be partially reverted to allow the original Ferguson firmware to be used. This can be useful to read out the ACM data on a modified Ferguson receiver.

This is a somewhat involved process and not for the faint of heart.

  1. Unplug the MAC board from the card reader board. Plug the MAC board directly into the receiver motherboard.
  2. Desolder the left and right audio wires going from the MAC board to the PAL board.
  3. Disconnect “VBC” and “VI” from the PAL board. Connect them together.
  4. On the underside of the PCB, a diode and a wire are connected to the centre pin of transistor TV19. Desolder the diode and insulate the end of the wire.
  5. Follow the service manual guide to set up VCO levels and RGB cutoff.

Beware that the insulation on the wire used by Trac has a tendency of melting easily. You may need to repair wires with splices and/or heatshrink to reinstall the mod.

LNB types

The Trac ROMs support three types of LNB:

Type LO offset Frequency range
FSS 10.0 GHz 10.9 to 11.7 GHz
BSB DBS 10.75 GHz 11.7 to 12.5 GHz
Telecom 11.0 GHz 11.95 to 12.75 GHz

The above assumes a receiver tuner range of 0.95 to 1.75 GHz.

DATA port enhancements

The Trac D2MAC/PAL modification adds a 0V/12V switchable output and a PAL video signal to the DATA port.

The DATA port is an 8-pin DIN socket.

DATA port pin Function
1 Ferguson: Data output
Trac: “VO”: +12V / 0V switchable – NOTE outputs -11V in “0V” mode
2 Ground
3 Ferguson: NC
Trac: Always-on PAL video to decoder. 1V p-p on approx. 3V DC level
4
5 Ferguson: NC
Trac: “DI”: Decoder video input
6
7
8

The video pins can be connected to a SVA-1 Videocrypt decoder's Decoder SCART port. The de-emphasis filter needs to be enabled if HackTV is being run with the “--filter” option.

RGB/LO tuning

Press Menu to open the on-screen setup menu. Hold Shift and press 9 on the remote.

  • Press Enter to switch to Decoder mode
  • Press Cancel to switch to Receiver mode
  • 1/4, 2/5, 3/6 adjust the RGB cutoffs.
  • 8/9 adjusts the local oscillator
  • 0 stores the new settings, VIEW exits without saving
  • Last modified: 2021/01/24 02:56
  • by philpem