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MID Block
Overview
A MID (Multi-Image Driver) is used in the RA-4 chassis for PIP and Twin-
View operations. This technology allows two images of any format to be
displayed at the same time in a 480 P format in separate windows. All of
the MID circuitry in this chassis is located on the BM board. Since there
are no extender cables available at this time, repair of the MID circuit will
consist of resoldering or replacing the BM board.
Mid Inputs
The BM board receives Y, U and V inputs from the main video and the sub
video. These two sets of inputs are each applied to their own ADC. IC003
and IC014 are identical 8-bit three channel analog to digital converters.
Their digital outputs are input to IC010 MID controller.
The BM board receives sync from the main and sub sync signals. These
signals are main VS and HS and Sub VS and HS. The V signals are 60
Hz and the H signals are 15.734 KHz. The BM board also receives sync
inputs from the VS and HS signals. VS and HS signals are output from
IC511 Video Processor (not shown) and are used as the synchronizing
signals for the deflection circuits. The VS signal is a 60 Hz signal, while
the HS signal is a 31.5 Khz signal. These signals are needed to synchro-
nize the input and output video signals.
MID Processing
When the customer uses the remote to enable PIP or Twin View func-
tions, data is sent over the I2C bus for the MID CPU. The MID CPU
interprets these instructions and commands the MID Controller to pro-
duce the proper output. The video output uses the two memory ICs to
manipulate the signals to produce the desired outputs. The MID CPU
also uses the NVM to store the settings of its parameters. These includes
picture modes, size of pictures, number of pictures, etc.
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MID Outputs
Once the processing of the signal is complete, Y, U and V signals are
output from the MID processor along with a MID YS signal. This signal is
used for positioning of the MID video signals into the picture. MID VS and
HS signals are also output from the MID Controller. These signals are
used as sync signals for the MID video. The VS signal is a 60 Hz signal
and the HS signal is 31.5 KHz.
MID Troubleshooting
MID malfunction will only cause problems with the PIP or Twin-View func-
tions. Some symptoms could be loss of PIP window or distorted PIP
picture. If the BM board is not producing vertical sync and a Twin-View
function is activated, the set will shut down and indicate a vertical failure
or produce a cycling power relay. If an antenna or video source is being
input, the symptom would be a cycling power relay (relay turning ON and
OFF every few seconds). If no antenna or video source were input, then
the Self-Diagnostics would indicate a video failure. At the present time
any MID failure requires the BM board to be replaced.
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Table of Contents
Troubleshooting
