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IBM 5151  -  Vertical Deflection  -  Some Waveforms


     
  High_voltage_warning.svg.png WARNING:

Opening the 5151 will expose you to dangerous voltages and currents.
Those threats can still be present long after power has been disconnected from the 5151.
Before opening the 5151, adequately educate yourself as to the hazards.
Some hazard examples at here.


Vertical sync pulses out of IBM MDA card.bmp Vertical sync pulses out of IBM MDA card.
   
5151_d401_cathode.bmp Cathode of diode D401.

( Vertical sync pulses differentiated to become positive and negative spikes. )
   
5151_d401_anode.bmp Anode of diode D401.

( Positive spikes removed. )
( Time expanded version follows. )
   
5151_d401_anode_expanded.bmp  
   
5151_tda1170_pin_numbering_solder_side.png TDA1170N

Pin numbering on solder side of PCB.
   
5151_tda1170_pin1.bmp Pin 1 of TDA1170N.

( RAMP OUTPUT )

Vert. Size potentiometer changes ramp height.

Vert. Linearity potentiometer changes linearity of ramp slope.
   
5151_tda1170_pin2.bmp Pin 2 of TDA1170N.

( SUPPLY VOLTAGE )

About +15V
   
5151_tda1170_pin3.bmp Pin 3 of TDA1170N.

( FLYBACK )
   
5151_tda1170_pin4.bmp Pin 4 of TDA1170N.

( AMP. OUTPUT )

What heads to the vertical deflection coils.
   
5151_tda1170_pin5.bmp Pin 5 of TDA1170N.

( AMP. VOLTAGE )
   
5151_tda1170_pin6.bmp Pin 6 of TDA1170N.

( REGULATED VOLTAGE )
   
5151_tda1170_pin7.bmp Pin 7 of TDA1170N.

( HEIGHT ADJUST )

I did not see a noticeable change in the waveform when adjusting the Vert. Size potentiometer.
   
5151_tda1170_pin8.bmp Pin 8 of TDA1170N.

( SYNC. INPUT )

NOTE: Only hundreds of mV.
   
5151_tda1170_pin9.bmp Pin 9 of TDA1170N.

( OSCILLATOR )
   
5151_tda1170_pin10.bmp Pin 10 of TDA1170N.

( AMP. INPUT )

Per here, those small pulses are about 200 mV in amplitude.

I was expecting a noticable ramp waveform.
   
5151_tda1170_pin11.bmp Pin 11 of TDA1170N.

( COMPENSATION )
   
5151_tda1170_pin12.bmp Pin 12 of TDA1170N.

( RAMP GENERATOR )