Sony D98 chassis Operation Manual page 12

2. H Linearity and Raster/Distortion Ringing Correction Circuit
This section includes HLC Control circuit which is new in D98, S cap switching and HLC/S-Cap Damping circuits. These
circuits are placed directly on the "cool side" of DY which is in series with deflection current line.
H Centering circuit will be explained in next section.
HLC Balance Control and HLC damping
There is no HLC switch for this chassis. Instead of that, HLC(L502) effectiveness is changed by LCT(503) for each Fh
since T503 and L502 is in parallel. LCT is Cross Transformer which can change its inductance accordingly to the DC
current of secondly side. The current of secondly side controlled by DAC output of MICRO through Q507. *It can be
changed by register "HLC BAL". R520 and C528 is damping circuit to avoid the Raster Ringing (mainly on left side of
picture) caused by HLC, DY and S-caps.
S-Cap switching and S-cap Damping
H Def current is distorted by resonance between S-Cap and DY to correct the linearity. Since the resonance frequency has
to be changed for each fH, S-Cap switching is controlled by MICRO
Switches are "On" when its gate is Hi(5V) and that moment, drain voltage should be grounded (0V).
L505, R522 and C513 is damping circuit to avoid Distortion Ringing (mainly on top of the picture) caused by S-caps and H
Control loop gain. L504, R523 and C527 is also the same purpose as above but only works when Q508 (Switch for the
Biggest S-Cap) is "On".
Troubleshooting
See attached "FLOW CHART" and confirm if it's really H lin issue.
Bad Linearity
Confirm that Raster is approximately in the center of the Bezel. If not, refer to next section (Raster Centering Circuit).
Check S-cap switches (Q508, 509, 510, 511, 512, 513) and confirm that H Linearity changes proportional to the value of
"S-Cap Direct". Confirm that H LIN BAL changes by the register value of "HLC Balance(Max/Min)".
If it's not working, check Q507 and the connection between N bd and D bd or, Check L502, T503.
Bad Top Distortion/ Left side Raster Ringing
Check damping circuits explained above or check the connection between N & D(HLC control line).
3. H. Raster Centering Circuit
Overview
H Centering is changed by supplying DC current to DY. D98 is taking the common level on DY cool(-) side and +/- 8V from
power supply transformer(T601 PIN#10, 11, 12. #11 is the common).
H Center Circuit
The DC current is outputted by powered OP-amp(IC502). This circuit is making "invert amp" with the gain of R549/R548
and input 1S Q515 collector. The level is controlled by MICRO"H CENT' through Q517(buffer). Q516 is Stand by-MUTE
switch which activates when "Remote On/Off' is Off(Lo).
Trouble Shooting
See attached "FLOW CHART" and confirm if it's really H Center Circuit issue.
No Raster Centering Control
Check R621, 622(Right next the SRT) first. If it's open, change IC502.
Confirm that voltage of Q5 l 5 base is changing accordingly to "H CENT MAX or MIN" register.
If not, change Q517 or check the connection between N and D.
Confirm that Q516 is Off. This circuit should not work when the Monitor is in Main mode.
Check IC502.
CAUTION!!
The heatsink of IC502 is connected to the H center(-) level, not GND! It could have up to 150V and should not be
touched to any other metals.
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