Rgb Out Board; Circuit Structure; Adjustment Method - Ikegami HTM-1990R Service Manual

RGB OUT BOARD

(1) Circuit Structure

(a) Voltage amplifying Circuit
(b) Current amplifying Circuit+BFS(Beam Feedback System) switch Circuit
(c) BFS (Beam Feedback System) sampling-hold Circuit
(d) Ripple Filter

(2) Adjustment Method

* When not otherwise indicated, HDTV is the standard for the input signal in the analog component of YPbPr.
* The figures are images are differ from the actual signals.
(a) VR101 [G FREQ.COMP]
VR201 [B FREQ.COMP]
VR301 [R FREQ.COMP]
Input the sweep signal to Y and flatten the difference in the levels of the encircled sections from low level
to medium level in the test points TP1 (B), TP3 (R), TP5 (G) of the CRT SOCKET BOARD.
Finally, adjust the Frequency Characteristic within +1dB/-3dB up to 30 MHz.
Note: Use the 100:1 high resist voltage/low capacity probe.
Standard
60Hz
Standard
60Hz
(b) VR102 [G CLIP]
VR202 [B CLIP]
VR302 [R CLIP]
Input the lamp signal to Y at the test points TP1 (B), TP3 (R), TP5 (G) of the CRT SOCKET BOARD and,
with the Terminal Resistoropen, gradually raise the contrast VR to increase the video level so that Adjust
the signal clips in the vicinity of about 55V.
-1dB -3dB +1dB
25MHz 30MHz
-1dB -3dB +1dB
25MHz 30MHz
Standard
60Hz
Clamp (applox. 120V)
Normal video level
55V
Clip video level
Section where video level clips
0V
-1dB -3dB +1dB
25MHz 30MHz
1-B-27