LA75695VA
No.7637-9/13
V19.V20.V21. Maximum, minimum AFT output voltage, AFT detection sensitivity [V13H, V13L, Sf]
(1) Internal AGC
(2) fp = 45.75MHz
±1.5MHz Sweep = 10mVrms (VIF input)
(3) Maximum voltage : V13H, minimum voltage : V13L.
(4) Measure the frequency deviation at which the voltage at test point B changes from V1 to V2.
f
V22.V23. VIF input resistance, Input capacitance [Ri, Ci]
(1) Referring to the Input Impedance Test Circuit, measure Ri and Ci with an impedance analyzer.
V24.V25. APC pull-in range [fpu, fpl]
(1) Internal AGC
(2) fp = 39MHz to 51MHz continuous wave; 10mVrms
(3) Adjust the SG signal frequency to be higher than fp = 45.75MHz to bring the PLL to unlocked state.
Note : The PLL is assumed to be in unlocked state when a beat signal appears at test point A.
(4) When the SG signal frequency is lowered, the PLL is brought to locked state again. f1
(5) Lower the SG signal frequency to bring the PLL to unlock state.
(6) When the SG signal frequency is raised, the PLL is brought to locked state again. f2
(7) Calculate as follows :
fpu = f1–45.75MHz
fpl = f2–45.75MHz
V26. AFT tolerance frequency 1 [dfa1]
(1) Internal AGC
(2) SG1 : 43.75MHz to 47.75MHz variable continuous wave 10mVrmns
(3) Adjust the SG1 signal frequency so that the AFT output DC voltage (test point B) becomes 2.5V;
that SG1 signal frequency is f1.
(4) External AGC (Adjust the V17.)
(5) Apply 5V to the IF AGC (pin 17) and then pick up the VCO oscillation frequency from GND, etc.;
and measure the frequency f2
(6) Calculate as follows :
AFT tolerance frequency : dfa1 = f2–f1 (kHz)
V27.V28. VCO maximum variable range (U, L) [dfu, dfl]
(1) Apply the VCC voltage to the external AGC, IF AGC (pin 17).
(2) Pick up the VCO oscillation frequency from the VIDEO output (A), GND, etc.
and adjust the VCO coil so that the frequency becomes 45.75MHz.
(3) fl is taken as the frequency when 1V is applied to the APC pin (pin 9).
In the same manner, fu is taken as the frequency when 5V is applied to the APC pin (pin 9).
dfu = fL–45.75MHz
dfl = fL–45.75MHz