Lift After Gamma Mod Alignment Procedure

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Modified Color Channel Alignment Procedure for Lift After Gamma Mod.

As created and written by Dave Corbitt

1. Check Power Supplies, adjust if necessary. All voltages should be within +/- 0.05 volts measured at the Color Channel.

Put the 100246 on an extender. Voltages available on the edge connector at the following points; +12v = pl 1-5, -12v = pl 1-31, +5v = pl 1-2.

Adjust the Scan and Signal PSU for +/- 12v and Traction PSU for +5v.

Parameter Test Conditions / Notes Procedure
2. Noise Blanking TK in Local, POS mode MASKING OFF On 100246, monitor "n.b.p." Adjust RV3 for pulse width of 4.25 us.
3a. Analog Test Ramp for TKs with 1132a Test Gen. a. (Staircase) / (Saw/Exp)

on 1132A to (Saw/Exp)

b. (Saw/Exp) to Saw.

c. (Norm/Head) to Norm.

On 1132a monitor POS and adj. RV2 for 20uS wide black level. Adjust "gain" for 0.8V p-p signal.
3b. Analog Test Ramp for Tks without 1132a Test Gen. a. (ST/Exp) on 246 to ST. On 100246 monitor ST/Exp. Adjust "Slope" for 20 uS wide black level.

Adjust "Amp" for 0.8V p-p signal.

4. Ref Check On 252 monitor "ref" and "e" (0V) Ref should read 2.25V +/- 0.05V.
5. Local Master Control Calibration Master Gain a. Connect DVM probes between "ref" and "green g" on 252. Adjust Master Gain on Local CP for 0V difference.
Master Gamma b. Connect DVM between "e" and "green γ". Adjust Master Gamma for +1.85V.
Master Lift c. Connect DVM between "ref" and "green l". Adjust Master Lift for 0V difference.
check red & blue d. Check that red and blue g, γ, and l are all within 10 mv of green g, γ, and l. (There are no adjustments for this unless you have mini-joysticks).
6. Calibrate Green log amp (247) Analog Test Ramp ON a. Monitor "in" on green 247and adjust "g amp" pot on front of 253 for 0.7V p-p. If "g amp" on 253 has insufficient range to achieve 0.7V, then center "g amp" pot and readjust "gain" on 1132 or "amp" on 246 for 0.7V at 247 input.

b. Monitor "wp" on green 247. Adjust "wp" pot until White Pulse and Sawtooth Test signal amplitudes match. See Fig. 1 Alignf1.png

1132 Saw/ Exp. to Exp. OR

246 st/exp to exp.

c. Monitor "out" on green 247. Adjust "lin" for most linear ramp possible.

Ramp will curl up slightly at the bottom. This is normal. See Fig. 2. Alignf2.png

1132 Saw/ Exp. to Saw OR

246 st/exp to st

d. On green 247monitor "out". Adjust "gain" and "set dc" for 700 mV pp on a 0V baseline. Controls will interact. Repeat until correct.
7. Calibrate red and blue log amps (-247s) a. With dual trace scope in Add/Invert mode, monitor "in" of red 248 on Channel A and "in"of green 248 on Channel B. Adjust red 247 "gain", "lin", "wp", and "set dc" to exactly match green.

b. Compare blue to green and adjust blue 247 as you did red.

8. Adjust -248 γ boards "γ bal" and "neg γ bal" set to mid position on all 3 -248s a. Monitor green 247 "out" and green 248 "out"with dual trace scope in ADD/INVERT mode. Adjust "γ" on green 248 to best match or null the 2 signals.

b. Monitor red 248 "out" and green 248 "out" in dual trace ADD/INVERT mode. Adjust "γ" on red 248 for best match or null. Rotate Master Gamma Control end to end and Adjust red "γ bal" and red "γ" until the red and green levels track or null over the entire range.

c. Readjust Master Gamma control to 0.4. Exact setting is not critical for this step. Monitor blue 248 "out" and green 248 "out" in dual trace ADD/INVERT mode. Adjust "γ" on blue 248 for best match or null. Rotate Master Gamma Control end to end and Adjust blue "γ bal" and blue"γ" until the blue and green levels track or null over the entire range.

9. Adjust 249 Exp. Amps Set γ hi/lo switches to γ lo position. "w clip" pots set to maximum level (white clip set as far level as possible) (all 3-249s) a. Use DVM to monitor "ref" and "green γ" on 252 board. Adjust Master Gamma Control for 0.V. difference.

b. On green 249, monitor "in 2". Adjust "γ lo" for 50mv p-p signal.

c. On green 249, monitor "out" and adj. RV6 gain (internal to 249) and "b clip" for p-p signal of 1.4V on a 5 mv black clip / pedestal level. See Fig. 3. Alignf3.png

Set green "w clip" d. Set Master Gain Control to maximum. Monitor green 249 "out" and set "w clip" for 1.66V p-p white clip level. Reset Master Gain to Center Point.
Calibrate red and blue -249s e. Use dual trace scope to monitor red 249 "out" and green 249 "out" in ADD/INVERT MODE. Adjust red 249 RV6, "γ lo", "b clip", and"w clip" to make the red 249 match the green 249. Master Gain may need to be rotated to insure both signals are in the white clip area. Do a similar alignment for the blue 249 relative to the green 249.
10. Adjust Negative black reference level. Set Master Gain, Gamma,and Lift to all be the same level as ref on 252 as in step 5 above. NEG mode, Analog TEST Ramp ON. a. Monitor green 249 "out". Negative peak of test ramp should just touch the baseline. Adjust RV5 internal to 100251 to make it so. See Fig. 4.