1769SL schematic.pdf part of CHUNTEX ELECTRONIC CO LTD 1769SL CTX 1769SL.rar, Schematic text manual preview

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CTX

1569DSE

Dead with tripping PSU

CTX CPS 1560LR CTX CPS 1560LR . Line output transistor dies soon after switch-on. . Too wide and E/W fault. Line transistor becomes hot.

Check IC701 (TL431), R717 (12K) and capacitor C721 (1uf 50V). If the capacitor has blown apart and the resistor burnt, check the line output transformer before replacing any components as in my monitor the transformer had literally melted at one side and a crack surrounded the transformer's middle. Obviously this transformer had developed a EHT to pin 11 short with catastrophic results. Replacement transformers are available but due to the cost it is usually more economical to scrap the monitor. [HV is present for a short while; 250V at collector if it is de-soldered, also when load is applied with a lamp]. Check downward control/PSU, add 200R to the Ub-supply to the line transformer if necessary. Check diodes and drive control transistor(s) in the width control. Overheating of the line transistor may be due to the line amplitude being too high. Check ZD101 (18Vdc) in power supply on left near front on main board edge, Q101 (92SK955-2SK956) on black heatsink in power supply, R114 (39R/2W 5%), IC101 (UC3842 - NTE7096J) and R113 (100R/0.25W 2%)on power supply's small daughter board, C113 (0.01uF/50Vdc) on daughter board, fuse (2.5A) on left edge of main board. Solder power supply's small daughter board connections at main board. Q101 (K118), D102, R104 (0R25/1W), F101 (Gma 3.15A). Squealing]. D108 (Bym26c), D410 (5thz52), Q402 (A953), R441 (2R2/0.5W), C407 (432j-pp630). Q103 (2SC3457), Q401 (2SC3886A) Check IC101 (UC3842AN), C112 (100/25). Check D108 (BYM26C), D410 (5THZ52), Q402 (A953), R441 (2.2-0.5W), C407 (432JPp630). Replace C123 (10uF/250V) and C427 (1uF/200V). Check C601, C602 and C603 on CRT board. Replace C431 (10uF/250V). Replace C427 (1uF/200V). IC402(LM317) and R449 bad solder joint. Replace C427 (1uF/200V). Check diodes and drive control transistor(s) in the width control. Overheating of the line transistor may be due to the line amplitude being too high. IC203 (C4557C). Clean pot VR407. Q408 (Ytf630). Resolder area including width pot VR401 and capacitor on the back of the board connected to it. Also resolder L406. Check Q408 (YTF630). Resolder area including width pot VR401 and L406. DBLCPS1560 CRT size: 15" SVGA.

CTX CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR Dead. Dead. Dead. . Power cycles. Shakes. Takes approx 15 mins to power up. . Dead. Squealing. Dim picture. Vertical size expanded. Squigly text. . Uneven colour; virtually green. . Intermittent pincushioning. . Pincushion when warm. E/W failure. Frequency switch does not work. . E/W error. . Too wide and E/W fault. Line transistor becomes hot. . Horizontal width and pincushion cannot be adjusted correctly. . Problems with the pincushion, related to the heat E/W and too wide. Pincushion effect and excessive width. . FCC information. . Specification.

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CTX CTX

CPS 1560LR

. Ripples in display like sine waves.

CPS 1560LR CTX CTX CTX CTX CTX CTX CTX CTX CTX CTX CTX CTX CTX CTX CTX PR700T CTX CVP 5468a CTX CTX CTX CTX CTX CTX CTX CTX VL700 VL700 VL700 CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR CPS 1560LR PR711T PR705F

Screen collapse. Ripples on display. Shape of a sinewave. After some time picturepulls in. . Picture distortion. Shakes. Jitter - takes approx 5-6 secs to power up. Trembles. Horizontal jitters. Dim picture. Vertical size expanded. Squigly text. O/W connection. . Slight frame jitter on all pictures. . Vertical size fault. . E/W failure. Frequency switch does not work. . Contrast control does not work. Dead. . PSU is S/C.

Check and replace C118 (100/350V). A hole is burnt in the PCB. Solder together with bridges R413 (220R), J112 and L406 46L00-0360LSE. R413 and J112 belong together. L406 comes from the top left-hand corner. (D. Luetkefent, Raublingen, Germany) C118 (100/350) in power supply. Check C602, C603 and C604 (2.2/50). Check C118 (100/350) and C115 (330/25). IC101 (UC3842AN), C112 (100uF/25V), C1xx? (2.2uF/450V) in rear of PCB. C118 (100uF/350V), C115 (330uF/25V [Noticeable in 800x600]. Check C115 (330/35). Replace C123 (10uF/250V) and C427 (1uF/200V). Check IC402 and surrounding circuitry for bad solder joints Replace C115 (330uF/25V) near chopper transformer is low, this supplies HT smoothing to IC103. Check C118 (100uF/350Vdc) on main board centre. IC402(LM317) and R449 bad solder joint. Defective solder at contrast pot.
Check C137 (47uF/250V). Q104 (2SK2648), ZD101 (18V), R126(0R22) are defective. Resolder flyback transformer, in case deflection is available, then line output transformer is defective. (FEA749 by power components). Protective resistor R405 (1R) in supply voltage for high voltage can also be defective.

No picture. Ticking sound. Cleared up a dim screen by adj "screen" cntrl on flyback. Also cleaned crt pins (did the most good). Then the H size went wide. Cannot find adjust. Diode or cap went?L304 and L305 does not help.

monitor powers up screen blank. Also high pitched whine 2085 in unit. 1795GM 1795GM 1795xe VL700

The common cause of too-wide in this chassis is one of two high-voltage film caps going bad, C313 & C314, often shorted. Values are roughly 0.01uF, but the exact values will vary due to fine-tuning at the factory, so check value. Also, in some, the OEM caps used were polypropylene, not mylar; if so, replace with same type, to prevent overheating. Check/replace C454 = 10 uF/250V. It can be accessed without having to disassemble the chassis, through a hole in the bottom, under the main PCB. It is also a good idea to check out other electrolytic capacitors as well, especially C121 & C104 = 1000 uF/16V.
[LED is green]. Fault can be intermittent. Replace Q335, Q314 and D320 in the

horizontal deflection stage. No picture, no HT. No sync because (Power Save). Intermittently no picture (occurs often after a few days), green LED turns orange of bad solder joints on the video board. C224 is defective. . E/W stage is defective.

Dead.

Dead. Dead. Dead.

Check AC inlet for damaged connections. Remove AC inlet jack and clean tin pins to ensure solid connection Check smoothing capacitor C440 (10nF/1kV) for G2 voltage leaky (reading 11K) also Q415 (BF488, used BF423 OK), R474 (33K/0.5W), Same parts in CTX1569 are Q721, R761 and C733. Power supply ticks]. Check horizontal output transistor and B+ line for a S/C. Check Q313 and Q306.

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Repeat failure of Q415 S/C and R474 burns up. No display. Power LED on. SMPS squeals. Picture has ragged edges. Squealing. No picture. . No display. Power LED on. Service mode. Takes few minutes until screen lights up. Picture has ragged edges. SMPS squeals. . Excessive brightness with retrace lines. Dim picture. . Excessive brightness. Brightness control has no effect.

VL700 1792UA 1792UA

. Brightness cannot be controlled. Paralellogramm failure. Pin balance failure.

Replace Q415 (BF488), R474 (33K/0.5W) and capacitor C440 (10nF/1KV). Check C125. Check R124 (82K/1W) for high resistance Check R124 (82K/1W). Check C125 . Hold down +/- keys while simultaneously powering up. Check CRT. Check R124 (82K/1W) for high resistance Replace R480 (240K/0.25W) next to small transformer T401, with 0.5W. [AC ripple]. Check R124 (82K) for O/C. Check Q336, D306, ZD402 and R480 Q336 (JC337-25) (Ecg123ap) leaks, D306 (a91n4148) leaks, ZD402 (12C/1W) S/C, R480 (240K/0.5W) O/C. Zener and resistor are likely main cause. D306 causes HV loss. Q336 checks ok but does not work.

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Specifications. Colour drop out. Picture goes dark. No picture, smoking. No contrast. OSD ok. Whistling depending on resolution. No horizontal synchronisation. Smoking. No function. Horizontal fails continuously after a short time. No picture. Wrong horizontal frequency. LED color is green. At times no function at start-up. Dead. No picture. PSU is defective.

Capacitor C303 is defective. Capacitor C351 is defective Screen size: 17" Dot pitch: 0.26mm Video bandwidth: 135MHz Horizontal frequency: 30-92kHz Vertical frequency: 50-160Hz Max resolution: 1600x1200 at 70Hz Resolution at 100Hz: 1024x760 TCO 95 Check solder joints on control board. Check C609.
Check IC601.

On the deflection coil there is a board with coils. Araldit has been spilt on this. Replace and adjust IC301 C673 ist burnt. Check Q313 and Q306. OR Zener diode ZD101 (18V) has short circuit. Check ZD405. HT ok]. uP is defective. Check keyboard function and check if mode date can be saved. In case not good check IC501, IC502 and XL501, then end of routine. In case it is good end of routine. Load electrolytic C104 charges up to 440V]. R143 is S/C.
Check fuse and D110 (BYM26C).

IC605 is defective. R124 voltage too high.

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1792UA 1792UA

Picture is dark, makes noises. Picture is too bright. No adjustment possible.

CTX

R124 in the PSU is defective (high resistive). IC605 (LM2405T) is defective. Then no sync. IC301 (C1883CT) is defective. Resistor R480 O/C. 1. Check power indicator LED. If not good refer to Power Supply CKT Troubleshooting Routine, otherwise go to next step. 2. Check LED colour. If it is amber refer to Power Saving CKT Troubleshooting Routine. In case it is green step next. 3. Does image appear? In case not appear step next, else step to paragraph 6). 4. Check (215V), (75V), (25V), (15V), (7V), (5V), (-12V), (12V), if not good see Power Supply CKT Troubleshooting Routine and Adjustment, else step next. 5. Check if raster appear. In case it appear step next, else see Deflection CET Troubelshooting Routine and Adjustment. 6. Check colour performance. If it is good step next, else refer to Video CKT Troubleshooting Routine, then step next. 7. Check geomertic performance. In case it is good step next, else refer to Deflection CKT Troubleshooting Routine. 8. Check external switch function. If not good refer to Micon CKT Troubleshooting Routine, otherwise no trouble found, end of Main Troubleshooting Routine. Check DC voltage of BD101 (+/-) pins. If not good check P101, F101, L101, L102 and BD101. Check gate voltage of Q104. If not good check Q101, D105, ZD101, C101, C105, Q104 and R126. Check AC output of T101 secondary coil. If not good check Q108, RL102 and T101. Check DC output of Power Supply, if it is not good check D101, D117, D109, D110, D112, D106, from Q107 to Q111. Check IC501, Q502, Q503, Q108 and signal cable. Check keyboard function and check if mode date can be saved. In case not good check IC501, IC502 and XL501, then end of routine. In case it is good end of routine. Check voltage of RK, GK and BK. In case it is good check CRT socket and CRT, else step next. Check voltage of IC601 pin 18, 20 and 23. If it is good check IC604, IC605, Q620, Q621, Q624, Q625, Q622 and Q623. Check pin 15 clamping voltage of IC601. In case it is not good check IC601, P605 (12V) pin 13 of IC601. Check signal input at pin 5, 8, 11 of IC601. In case it is OK check R654, R656, IC601, P605 (12V) pin 7 of IC604, else check C603, C610, C615, R602, R605 and R609.

1792UA

Main Troubleshooting Routine.

CTX 1792UA CTX 1792UA LED color is amber. Power Supply Circuit Problem.

CTX

1792UA

Video Circuit Problem.

CTX 1792UA CTX 1792UA H-Asynchronous No raster.

Voltage at pin 2 of FBT is not ok (disconnected pin 1 of FBT and collector of Q403)]. Check 215V, Q338, R425, L402, C407 and R403. [Base voltage of Q403 is not ok]. Check T402, Q402 and C414. [Q338 gate voltage is not ok]. Check IC303, C398, R496, Q333 and Q332. [Q338 gate voltage is ok]. Check R425, R453, L402, L407 and C410. Short TP301 to ground then adjust free running of H-Hold VR302. [Voltage at pin 20 of IC301 is not ok]. Check pin 38 of IC501 (H- F/V), Q507 and Q508. [Voltage at pin 20 of IC301 is ok]. Check voltage at pin 21, 22, 23 of IC301 and their peripheral parts. Check IC304, C331, D309 and Q305. Check base voltage of Q321, Q320, Q319 and Q344 are "L", "L","L", "L" (1792E/ES) when timing is 31K. Check pin 16, 17, 18, 19 of IC501. Check base voltage of Q1319, Q320, Q321 are "H", "H", "H". Model (1769E/SE) when timing is 69K. Check base voltage of Q319, Q320, Q321 and Q344 are "H", "H", "H", "H", model (1792E/SE) when timing is 92K. Check Q318, Q317, Q315, C356, C358, C354, C361. Note: "L" means the voltage between the gate and source is less then (4V) wich can't turn on the MOSFET. "H" means the voltage between the gate and source is equal or above (4V) wich can turn on the MOSFET. H-phase voltage pin 1 of IC501 is not ok]. Check IC502 and IC501. [H-phase voltage pin 1 of IC501 is ok]. Check R501, R327, R271, R223, C326. Adjust external H- Size and VR301. [Pin 1 of IC302 is OK]. Check IC304, Q307, Q308, Q309 and Q306 and their peripheral parts. [Pin 1 of IC302 is not OK]. Check pin 29 of IC501 and their peripheral parts. [Pin 5, 32 of IC501 is not ok]. Check IC501, IC301 and signal cable. [Pin 5 of IC503 is not ok]. Check IC503. Check Pin 2 of IC201. [Pin 2 of IC201 is not ok]. Check IC201, E205, C215 and Q511. Adjust external switch of side-pin control. [Voltage on pin 3 of IC301 is ok]. Check IC301. [Voltage on pin 3 of IC301 is not ok]. Check pin 36 of IC501. [No volatage on pin 36 of IC501]. Check IC501. Pin 9 of IC301 is not ok]. Check IC301, IC501. [Pin 9 of IC301 is ok]. Check D205, IC201 and C215. [Pin 4 of IC201 is not ok]. Check IC501. [Pin 4 of IC201 is ok]. Check IC201, D204 and C225. Voltage on pin 8 of IC301 is not ok]. Check IC501. [Voltage on pin 8 of IC301 is ok]. Check IC301. Check C440 (10nF/1KV).

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Picture left square is bigger than the right square. Out of phase.

CTX 1792UA CTX 1792UA CTX 1792UA CTX CTX CTX CTX 1792UA 1792UA 1792UA 1792UA Side pin distorsion. V-Asynchronous. Vertical position. Vertical size. Q415 and R474 blown repeatedly. No vertical scan. Abnormal width.