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All-In-Wonder X1800 XL: RF Section, Audio Section, Video Decoder

Exposing the RF section was as simple as undoing a single screw and levering both screens up with a flat screwdriver out of their clamps.


Front view


Back view

Under the top screen we found a lot of miniature inductance coils, a tiny quartz resonator and the heart of the RF section which is a wideband semiconductor tuner Microtune MT2121 that supports a 48MHz to 1GHz range and consumes just a little over 300 milliamperes. Earlier, for example on the All-In-Wonder X600 PRO, they used the MT2050 chip that featured the same level of noise (9dB), supported a wider range of operating temperatures, but had a narrower frequency range. But is it really necessary for a computer TV-tuner to be able to work under ambient temperatures from -40° to +150° centigrade? The Microtune MT2121 can also receive signal in the digital DVB-T format, although only the European version of the AIW X1800 XT supports this feature (it has an additional digital demodulator NXT 6000 that outputs an MPEG-2 stream; the CPU load should be very low at that because it is the GPU that decodes the stream).

Two SAW filters from Micrologic, M3951M and M9370M, are located below the RF unit. The filters are set at 45.75MHz and 41.25MHz, respectively. These intermediate frequencies are standard for the NTSC format the American version of the AIW X1800 XT supports. The European version uses EPCOS K3953M and K9456M filters set at 33.90 and 38.90MHz which correspond to the PAL format. Lower still, there is a demodulator chip, Philips TDA9887, which supports all existing analog TV broadcast standards and does double duty as an FM demodulator.

Another important part of the system is comprised of three chips that can be found right behind the DVI-I connector: the Philips TDA7040 chip allows listening to FM radio stations in stereo; the Fairchild Semiconductor CD4052 chip is responsible for commutation; and the Philips UDA1380 chip combines a stereo ADC with a sample rate up to 55kHz and a stereo DAC with a sample rate from 8 to 100kHz. So, the latter chip is responsible for the audio section of the AIW X1800 XL multimedia card, but unfortunately it does not support DVD-Audio format. Judging by the parameters of the UDA1380, the quality of the audio section of the card is rather high, but doesn’t quite match the quality of high-end audio equipment.

An ATI Theater 200 chip, the nervous center of the multimedia section of the AIW X1800 XL, is installed on the reverse side of the PCB. Its main purpose is to convert analog video signal into digital form and the chip does it by means of its two 12-bit video-ADCs which, coupled with special 2D comb and smoothing filters, ensure a very high conversion quality. Besides digitization, the processor performs hardware image scaling and decodes the audio track. The Theater 200 is a universal chip, supporting BTSC, Dual FM, EIA-J and NICAM formats. For some unclear reason, they didn’t implement sound transfer through the internal bus, so you’ll have to attach the audio output of the AIW X1800 XL to the line input of your audio card to hear the sound. Sound can also be outputted digitally onto an external DAC/decoder, but the 24-bit mode is not supported at that, although the sample rate can be as high as 96kHz.

Since the included TV encoder doesn’t support video playback in RGB format, the European version of All-In-Wonder X1800 XL features an additional VIA VT1623 chip responsible for SCART RGB support. The chip includes four 10-bit video-DACs, which ensures quality signal conversion.

 
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