43) aoc 수리내역

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QUESTION NO. P72303-10:  AOC monitor spectrum 4v has power green led but has no display.

Check diode near power supply, damper diode (her 303,stpr 303).

QUESTION NO. P70703-2:  AOC 7klr monitor.  Need value of r626, burnt beyond recognition.

Value of R626 is 820E 1w.  After replacing screen shows thin lines and foldover on top.  Changed TDA 4866 and electrolytics around this IC.  Fixed the problem.

QUESTION NO. P52903-4:  AOC 7Glr monitor.  I need the value of R913 and R914.

R913  4.7K 5% 1/4W, R914 47 ohm 5% 1/4W.

QUESTION NO. P111802-2:  AOC 5E monitor FCC ARSCM350S.  Need part number of D922.

This is a high failure part. Original is STPR320. It should be replaced by SUF5402 or UF302G.

QUESTION NO. P40302-8:  AOC Spectrum 4Vlr monitor has no +12V on output of regulator, on Q909 E = 14V, C = 0V output to IC904, B = 0V (If I open J041 = 14V).  Replaced Q909, IC904 and surrounding caps.

I believe Q909 will not turn on, unless activated by Q910, and Q910 is turned off bythe "suspend" mode pin, of the uProc IC.  That is to say, the uProc has shut down thismonitor, by turning off Q910 and Q909, and so Q909 is not the source of the fault.

QUESTION NO. P212-7: AOC 7G1r monitor, I need a replacement for SUF5402? D921.

This will be a 200 Volt, 3 Amp, ultrafast rectifier.  Possible substitutes include SF34 or UF5402, available from suppliers like Mouser Electronics (www.mouser.com), or NTE/ECG type 588.

QUESTION NO. P1015-9:  Need part number for Q901 in power supply of AOC 4V monitor.

Q901 is IRFBC40.  This should be available almost everywhere.

QUESTION NO. P511-5:  AOC 7VLR monitor, need to identify HOT.

The original HOT is the 2sc50498.

The hot is actually 2sc5048.

QUESTION NO. P418-5:  AOC 5En monitor starts up after replacing shorted Q403 (2sc5296) by BU2508DF but runs hot quickly and blew it after fifteen minutes.   D408 (3legs) was ok.  What semiconductor is this?  B+ pin 2 of flyback is 125V without signal.  I tried one more BU2508DF but after a couple of minutes monitor was dead.  HOT survived.  I checked D408 again, now two legs measured short.

Transistor 2SC5296 crosses to NTE2324.  A more suitable substitution would be BU2508AF not BU2508DF which has a built in damper diode.   2SC5296 is available from MCM for $2 or $3.

QUESTION NO. P210-6:  AOC CM-335 monitor with poor horizontal deflection, around 4 cm short, on both sides.  I adjusted carbon core coil near horizontal circuit but image still not wide enough.  Are there other adjusting points to check?

First, AOC CM335's are not full-screen monitors.  Expect about 1 inch of black border on each side, that is normal.  To widen these, adjust L402, or raise the B+.

QUESTION NO. P128-8:  AOC cm-735 monitor.  I tried to demagnetize the crt but there are stains which cannot be demagnetized and they are at the same place (cannot be moved).  Is there some way to remove this coloful stains on the crt

Either the tube was dropped and the shadow mask is damaged or the purity magnets are damaged/mis-aligned.

QUESTION NO. P628-8:  AOC CMLB-736 monitor was dead.  After changing Q804 2SC3996 and Q805 which were short cicuit, the set worked for short time with reduced width and Q804 running very hot.  The HT voltage seems to be correct and I have checked the capacitors around the HOT.

Replace C821 (between T801-HO-Driver and Base/HOT) 4,7킚/35V.

QUESTION NO. P614-10:  AOC CM335 monitor is dead and the internal fuse is okay. There are no obvious burnt components or dry joints on the boards. The power on lamp is not lit and the switch checks out okay. The thermistor is warm to touch when on for a while. Are there any typical problems that I may check before I suspect the LOPT.

The usual cause of the AOC CM335 PSU not starting is a high or o/c R907/R908. If the HOT is shorted replace C512. Also replace C512 if the HOT runs too warm.

QUESTION NO. P67-2:  Aoc 17" mod?e 7Hlr avec q420(bu2525ax) en court circuit et r113=1ohm/1w coup?mais tout grille de nouveau apr? quelques minutes de fonctionnement.

I believe this chassis is the same as the Royal 1782 model (FCC# HSU). The usual problem is the horizontal driver transformer has a defect, and overheats Q420.   If you cannot rewind the transformer, or find a replacement, one trick is to solder a second capacitor = 10 uF/63V in PARALLEL with C476 (near center of board, below Q411). This should cause Q420 to run cooler if the transformer was the  problem. Also check R498 = 1 ohm/2 Watt, Q414, T403, FET Q103 and the black cylindrical coil close to this FET, and the diode in series with R113.

QUESTION NO. P524-2:  AOC 4Nlr monitor. It works fine in DOS and Windows at 640x400, but at 800x600 the picture rolls.

Check out IC201, the Weltrend WT8042 chip, as well as its crystal/resonator, and any associated capacitors. LJ Enterprises, MCM, and others carry these IC's.

QUESTION NO. P325-9:  AOC CM-335 monitor.  Line output transistor (Q405) replaced 6 months ago with C4769 (2SC4769??) has failed again.  Is this the correct component for this monitor?  Also is there any known historical reason for early failure of this component?

The AOC CM-335 has several different chassis versions, with differing FCC numbers.  In FCC#ARSCM3352, the H.O.T. is Q405 and that one is 2SC4769. This H.O.T. may fail due to a bad horiz. drive cap C417 = 47uF/50V, next to T401, the drive transformer.

QUESTION NO. P29-4:  What is the value of Q427 on the main board of an AOC model 7Hlr?

Answering my own question, I finally found a service manual for the AOC 7Hlr monitor. Q427 is a BU2525AF.

QUESTION NO. P129-8:  AOC CM-336 14".  The monitor was dead.  I found one bad diode 31-df and replaced it.  The monitor was good for only 2 hours.After that the same diode was bad.  I put a new one in, but I measured the current which was flowing through the diode,the current in one direction was 0.5A, but in the other it was 1A and it was raising constantly.

A diode conducting current in both directions like that is no longer a diode, it is silicon slag. The "31DF" series devices are all rated 3 Amp, and Trr < 30 nsec, but you didn't give the number that follows the "31DF", which gives the voltage rating, in hundreds of volts.  Those currents did not exceed 3 Amps, so if you have used the same voltage 31DF rectifier, check if the reverse voltage is peaking  so high that the rectifier is breaking down. If you did not use an exact substitute, did your replacement 31DF have a voltage rating that was lower than the original?  Or did you substitute a different type rectifier, with a Trr that was too slow?

QUESTION NO. P1024-2:  I have an AOC CM-335 monitor with poor horizontal deflection (ie 2 inches short, both sides).  There is no adjustment on the front, and no labeled pots inside.  How can I make the display wider?

You should look for a carbon core coil on horizontal ckt and adjust the core so the image is the way you want it.

QUESTION NO. P219-2:  Burned components on power supply board in monitor AOC model:cm-335.  What is the value of ZD904?

ZD904 is 6v/1watt. You can use ECG 5070A.

QUESTION NO. P123-3:  Burned components on power supply board in monitor AOC model:cm-335. I need the value of resistors R937, R927, R941 & diodes D942 , ZD951?

R937=820ohms, R927=1Kohm, R941=270ohm, D942=ECG915, ZD951=6volt.