Onkyo TX-DS939 User Manual

ONKYO USA CORPORATION

200 Williams Drive • Ramsey NJ 07446
201-825-7950 Fax [phone]

499DS939NOTE_2

TX-DS939 06/17/99

Reading Material
Analog:

SYS CON: Q7001 is the main processor used to function (operate) the 939. This IC has multi input for its functions
while having various references inputs to enable or disable multi input port commands. The one being KEY matrix
configuration K0 ~5 the other is a serial port type. The Sys Micro does not require an external serial to matrix
converter (data translator). A number of output data are available from this particular IC to perform different tasks.
On page 22 and 23 the pin ID and description provides the insight of the Micro. The multi switching (multi
switching point) technology employed in this Micro though is not new except it has not been applied in the
consumer electronics technology. The assigned source signal demanded by various departments and is made
available through a multi-switching technology. Thus Cross Point takes effect when a single source is selected by
more than one request or device, or multi input are assigned to multiple locations through the same switching
technology. In either case the SYS Micro will be considered multi switching (CROSS POINT). The multi tasking
Q7001 provides numerous data, clock and strobe lines for various operational components in which each component
will identify and process data sent and function accordingly.

The control data switch entry is basically typical of most Micro System arrangement. A matrix configuration will be
used as a key data entry or serial data format or in some instances both may be used. The system control IC (Micro)
requires the presence of secondary processor (s) and its clock is being referenced at pin 72 and 73. With the absence
of these reference signals the main micro could go in to a shut down mode. Therefore it is best to understand the sub
micro found on DSP PCB must be present and operational as well.

FM: The FM in TXD939 is almost identical to that of the TXDS838. The System control IC Q7001 drives
Q1107 LM7001 normally known as Pre-Scale. Its task is to be able to switch between AM, and FM using the DATA
as well as provide (interpret data) tuning voltage needed by the tuner section by converting the PLL frequency. The

IC LM7001 is very much dependant on data and clock just as much on reference frequencies obtained from the AM
and FM local oscillators at pin 10 and 11. It is important that one check the local osc. frequency is not altered or
reduced significantly by a buffer transistor such as TR3 found in the front-end pack. The rest function of the tuner is
basic and open to logic. Q1119 is FM B+ switching transistor whish is triggered by pin 8 of Q1107 while Q1118 is
turned on by pin 9 to turn on AM. It is important to observe that the local oscillators of FM and AM not ON at the

same time due to defective switching transistors. FM in this circuit has 4 tunable (diodes) DIACS D1, D2, D3, and
D4. The AM section has only L1111.The B+ needed for AM and Fm should be free from ripple voltage.

INPUT OUTPUT selector:

The 939 provide individual channel input buffering that helps reduce residual noise and breakdown of input selector
ICs often suffered by Control amplifiers and receivers. The Data dependant input switching IC’s such as Q3208 and
Q3209 will greatly benefit from such input design. Depending on the instruction data received these IC’s provide a
multi switching (cross-point) input and output points. REC outputs are fixed and they proportionally equal to
original inputs. Pre-Processed signals derived from tone amp and DSP shall have a level control in place to vary
output to a desirable level. For such Q4423 and 4623 and like components are used. These components are also data
driven and clock dependant. Any clock missing will fail the operation of that circuit which may be affected by it.
Clock and data deformation between functional PCB terminals does happen do to an abnormal load on data line.
When such problem arises, one could expect a problem that would be considered Micro is defective when in reality
it is not.

Composite OSD (On Screen Display):

The on screen display function basically provides a system setup menu using an external monitor. The IC has two
crystals being used. One is being 17.7mhz and the other 4.3mhz. The IC is designed to depend on External Sync
input at pin 20, which employs vertical and horizontal locking since the sync being used is an extract of original
signal. It also has a Sync detect input at pin29. Pin 18 and 20 share a common video source line where pin 20 is
filtered through the RC networks to provide a near Sync only signal. CVOUT (component video output) is obtained
and further amplified by Q2151, 2252, and 2253. The output from this amp is fed to two types of monitor outputs.
The Composite Video (CV) and S-Video (YC) monitor output.

S-Video OSD (On Screen Display):

The S-Video monitor output is partly processed in this manner. The Y part of the YC out is mixed through Q2541
for OSD and Q2542 for the Luminance. The C part of the YC out is mixed through Q2641 for the OSD and Q2642
for the Chroma. The composite monitor output is processed in the same manner except it will use the switching
transistor array configuration Q2041~ Q2044. Weather an OSD signal should be merged with the video signal or not
is made by Q2951 which is a data driven switching IC.
Recording part of the Video is switched by Q2002 for composite and Q2602 and 2502 for YC signal. Input selection
is accomplished through Q2001 for composite and Q2601 and Q2501 for YC signal inputs.

VIDEO Switching: