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Atari Technical Bulletin TN008 - Mark - 07-21-2023
Technical Bulletin TN008
Date: 17 April 1986
Re: STM UHF Modulator Adjustment
The UHF TV output may not appear central on some TV sets, slight modulator adjustment should
correct inconsistent positioning.
Proceed as follows:-
1. Only Qualified service personnel should attempt to carry out the following procedure on the
520STFM and 1040STFM as mains voltage exists within these models.
2. Remove plastic cover and R.F. shield
3. Remove modulator shield
4. Apply power and adjust the plastic cross head screw on the modulator PCB until the display is
central.
5. Replace shields and all screws.
As well as producing a modulated output, the STM also provides an un-modulated composite colour
output on pin 2 of its 13-pin Din socket which connects to pin 20 of the Atari Scart Connector.