Memotech Limited MTX 500, Service Manual

Page: 47 / 78

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Test and setting procedure of UM 1286 and video board
1 Be sure that your TV set, MTX computer and any
other test equipment is switched on at least half
an hour before beginning the test.
2 Connect the MTX computer to the TV set by the
aerial cable.
3 Set the TV set to channel 36 of the 1V band (UHF)
to obtain the best combination of sound and
colour.
4 With the aid of a frequency meter, check the audio
carrier; if (for PAL A units) it is not 6 MHz
(values allowed: 5.99 - 6.01 Mhz) turn the sound
frequency adjustment coil (Fig ii) of the
Modulator to set it.
5 The video carrier is now set by 2 resistors
running in series at RV1 (a 10K OHM and 1K OHM).
These resistors can be replaced with a 1K MHz
variable resistor.
6 The two brass screws in the modulator (fig ii) are
cable compensators and shouldn't really be
tampered with.
FOOTNOTE
Whilst carrying out any tests on the MTX it is
advisable to detach the Mother P.C.B. from the bottom
chassis. If after following the trouble shooting guide
you still have problems - Replace the Mother Board and
refer to Manufacturers.
NB: Any channel adjustments carried out on the
Modulator should be done with the automatic
frequency switch of the TV turned off.
In the event of a TV not having an AFT switch
disregard this footnote.
MTX Service Manual