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Fixes and improvements for Metronic twinbox evo 2

This section is dedicated to terrestrial and satellite television set top box decoder Metronic twinbox evo 2 (441525) and also applies to its clones, see list of clones. Some flaws were found in its operation and some fixes and enhacements for them are presented below.


Enhaced firmware

When this device was new most television broadcasts were standard 4:3 format thus little attention was put to properly handle widescreen 16:9 contents. As time went on the number of 16:9 programs increased dramatically and so did the evidence of its poor widescreen support. In this section the receiver handling of 16:9 broadcasts will be improved.

The firmware code running in its microprocessor decides how video is processed and how will presented on the screen depending on its format parameters. To enhace this, its firmware has been dissassembled, analyzed to find out the code that sets video settings for 4:3 and 16:9 formats and modified for a better behaviour. Also I have done some other improvements.

The microprocessor STi5518 is built around a ST Microelectronics core type ST20C4 that executes a custom ST instruction set. The first 13 bytes in the firmware file are a header for the firmware update program and must be discarded for the disassembly.

This improved firmware file is compatible with the following models:

Firmware download:

Included in this archive is the original firmware (Original.bin) dated August 2006, the improved firmware (Modificado.bin) and documentation describing the modifications. It is compatible with terrestrial tuner NhPH1/3, receivers with other tuners can be used without terrestrial reception (satellite only).

To load this firmware into your set top box you need a serial port available in your PC, a direct serial cable (not null-modem) and the program ReceiverLink 1.2 that you can download from Internet. In order to apply the improvements you need to load only Modificado.bin.


Improved handling of 16:9 video:

Corrected some Spanish texts:

Transponder lists updated:

Technical notes

This is a detailed list of modified bytes in the improved firmware file and how they relate to improvements.

Position (HEX)Original value (HEX)New value (HEX)Description
25DF7424FDisable picture scaling in 16:9 mode
25D4A22 22 4322 24 40Correct picture size in 16:9 and Letterbox modes
25EBA424FGet rid of black borders in 16:9 mode
4C4EAdjust black border size in Letterbox mode
25C6F27 A7 40 D0 22 2D 40 21 72 21 21 5D 30 81 22 FC D1 40 21 72 23 21 28 51 30 38 21 72 21 21 5D 30 81 21 FA D2 41C0 28 A8 21 72 23 21 28 51 30 39 C3 21 72 23 21 28 51 30 39 C6 24 FB 2E A9 21 72 28 2E 25 25 94 C1 2D AF 26 06In Letterbox mode switch scaling and black borders depending on tuned channel. In 16:9 mode disable picture scaling.
25E114142Adjust black borders in NTSC Letterbox mode
B3B0DC0 22 A3C1 21 A8Always output VCR scart bypass as 4:3
BB38E68 25 2F 97 8A 2B F969 2C 25 28 90 63 F0Fix 16:9 signaling through scart pin 8 in 16:9 mode

Corrected Spanish texts:

Position (HEX)Original text (ASCII)New text (ASCII)
9FE03Vista Fin
9E891Canal escogodoCanal escogido
9ECF0Codificar !Codificado!
9F5CFLenguaje OSDIdioma menús
A02E4Deberia deDebería
ún eventoUna vez
9FA62instalar Inicio en Canalesindicar canal inicial

If you perform a binary compare between the original and improved firmware files you will find differences within position range 20F5D to 22B3F, this is the updated internal table of satellite transponders. There are more differences somewhere else as the user satellite transponder lists are also updated accordingly through a factory reset.

Power supply repair

A common fault in the power supply of these receivers causes a flashing to show up on its led display. This is due to a dry electrolytic capacitor that can be replaced at low cost, however you need a soldering iron, tin and some skills soldering electronic circuit boards.

When you open the case you will find two boards inside, the smaller board where power cord plugs in is the power supply. You have to lift this board by removing all screws that hold it in place to work on the solder side. If you have an ESR meter check all electrolytics, otherwise replace the capacitors depicted below.

Power supply capacitors C18 and C17

You have to replace capacitor C18 1000µF 10V and if this does not fix the issue also C17 1000µF 16V. Important! New capacitor must be installed with the same polarity as the original. Capacitors have a vertical stripe pointing to their negative terminal and they must be installed like the originals. In addition the negative terminal is silkscreened on the board as a filled half circle and must match the capacitor stripe side.

If you order a replacement it is recommended to request low ESR 105°C capacitors. They are slightly more expensive but will last longer.

Remote control fix

Some units exhibit an intermittent operation of their remote control and it may look like the set top box has poor sensitibity to infrared commands. This problem is due to noise in the infrared sensor ground pin (located on front panel board). The ground plane in this board is poorly designed and the infrared sensor is attached to the same trace of copper that carries all current from the led display to ground. The led display is multiplexed resulting in pulsed current that adds enough noise to disturb its proper operation.

To fix this problem solder a short wire between infrared sensor ground (middle terminal) and ground of its supply capacitor, as shown in the following picture:

Nodes to solder on front panel board

Although nodes connected by this wire are already interconnected by copper traces in the circuit board, this wire stops the led display current pulses from joining the infrared sensor ground and ensure a noise free ground for the sensor.

Project completed on December 2011 by Jeroni Paul.
Copyright © 2011 Jeroni Paul.

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