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JVC TV AV-21FMG3B , Excessive Voltage On HOT & burn the

 
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Tedy
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PostPosted: Mon Jan 14, 2008 12:27 pm    Post subject: JVC TV AV-21FMG3B , Excessive Voltage On HOT & burn the Reply with quote

I have a JVC Tv MOdel , AV-21FMG3B, there is an excessive voltage ( 180V) on the collector of HOT & when i change the Horizontal Transitor it was shorted again. When i checked the Voltage on the collector then it was 180v at first then it decreases down 1 by 1 to it's normal ( 110- 120 v). & the same thing ( the voltage ) on the capacitors one around the HOT & the other around powersupply which are 160V ,100uf . So what could be the cause for the excessive voltage on Collector of HOT. help me plz.
Tedy
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gary



Joined: 05 Apr 2005
Posts: 584
Location: MANCHESTER, uk

PostPosted: Tue Jan 15, 2008 9:23 am    Post subject: Reply with quote

replace any low voltage capacitors in the primary of the psu and in the psu feedback circuit,
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tedy
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PostPosted: Wed Jan 16, 2008 9:21 am    Post subject: Reply with quote

what else do i have to check or replace
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PostPosted: Sat Jan 19, 2008 6:59 pm    Post subject: Reply with quote

I have chnaged 2 capacitors ( 35v - 47uf & 50v- 4,7uf ) in the power supply ( primary ) near ther STR but nothing chage the voltage is the same. so what do i have to check or change , help plz
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gary



Joined: 05 Apr 2005
Posts: 584
Location: MANCHESTER, uk

PostPosted: Mon Jan 21, 2008 9:22 am    Post subject: Reply with quote

replace the str
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PostPosted: Wed Jan 23, 2008 9:50 am    Post subject: Reply with quote

But I have changed the Str coz it was shorted, I just changed it & then i was having this problem ? The STR is new ? Can it be the fault ?
tedy
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PostPosted: Wed Jan 23, 2008 10:23 am    Post subject: Reply with quote

But I have changed the Str coz it was shorted, I just changed it & then i was having this problem ? The STR is new ? Can it be the fault ?
tedy

And i also forget to tell u that when i changed a capacitor 25v 1000uf in the secondary near the transormer the voltage is now 120v on the collector of HOT but it still reduces 1 by 1 to 84v so tell me about his plz & does it have a problem if i simply mount the Horizontal transistor with the voltage 120v on the collector ?
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Gravityboots



Joined: 09 Jan 2008
Posts: 38

PostPosted: Wed Jan 23, 2008 11:21 pm    Post subject: Look through thesev and see if a plausable match exists Reply with quote

JVC AV2000 N/A NO SOUND OR PICTURE - BUZZING SOUND FROM SWITCHING XFRM. - HIGH VOLTAGE BEINGS TO COME UP THEN SHUTS DOWN CHECK/REPLACE C916 (P/N# SBTP-0038)
JVC AV2010 N/A NO SOUND OR PICTURE - BUZZING SOUND FROM SWITCHING XFRM. - HIGH VOLTAGE BEINGS TO COME UP THEN SHUTS DOWN CHECK/REPLACE C916 (P/N# SBTP-0038)
JVC AV2051 N/A NO VERTICAL SWEEP CHECK/RESOLDER CONNECTIONS ON VERTICAL OUTPUT IC OR REPLACE - LA7838
JVC AV2051 N/A BRIGHT RASTER BUT NO PICTURE CHECK/REPLACE Q710 (P/N# 2SA933S(RS)-T )
JVC AV2051 N/A LOW VOLUME EVEN THOUGH OSD VOLUME BAR IS AT MAXIMUM CHECK/REPLACE D652 (ECG177) LEAKY
JVC AV2058S N/A NO SOUND OR PICTURE - ONLY RASTER CHECK/REPLACE IC801 (UPC1486C)
JVC AV2058S N/A NO POWER CHECK/REPLACE D921 FOR SHORT
JVC AV2058S N/A PIX FADES IN AND OUT AND ALSO PIX TAKES ABOUT 30 SECONDS TOLOCK IN. CHECK/REPLACE IC801 (UPC1486C)
JVC AV2059S N/A DISPLAY WILL NOT TURN OFF AND THE CLOCK DOES NOT WORK CHECK/REPLACE IC681 (AN7168) FOR LOADING DOWN THE 5 VOLT
JVC AV2059S N/A SET TURNS ON FOR 5 SECONDS THEN SHUTS OFF CHECK/REPLACE IC681 (AN7168) FOR LOADING DOWN THE 5 VOLT LINE.
JVC AV2061 N/A LOW VOLUME EVEN THOUGH OSD VOLUME BAR IS AT MAXIMUM CHECK/REPLACE D652 (ECG177) LEAKY
JVC AV2071 N/A LOW VOLUME EVEN THOUGH OSD VOLUME BAR IS AT MAXIMUM CHECK/REPLACE D652 (ECG177) LEAKY
JVC AV20720 N/A BUZZING OR MUTING OF THE AUDIO ON SOME CABLE CHANNELS ADD 47pF (QCS31HJ-470AZ) FROM THE BASE OF Q161 TO GROUND
JVC AV2073 N/A NO SOUND OR PICTURE - BUZZING SOUND FROM SWITCHING XFRM. - HIGH VOLTAGE BEINGS TO COME UP THEN SHUTS DOWN CHECK/REPLACE C916 (P/N# SBTP-0038)
JVC AV20730 N/A BUZZING OR MUTING OF THE AUDIO ON SOME CABLE CHANNELS ADD 47pF (QCS31HJ-470AZ) FROM THE BASE OF Q161 TO GROUND
JVC AV2081S N/A NO COLOR SYNC - BARBER POLE EFFECT CHECK/REPLACE IC101 (P/N# TA8725N)
JVC AV20TP3 N/A UNIT WILL NOT TURN ON AND FLYBACK BUZZES CHECK/REPLACE IC101 (P/N# TA8725N-J)
JVC AV20TP3 N/A BRIGHT SCREEN WITH RETRACE LINES CHECK/REPLACE Q709 AND Q710 (P/N# 2SA933S(QR)-T )
JVC AV2120 N/A NO SOUND OR PICTURE - BUZZING SOUND FROM SWITCHING XFRM. - HIGH VOLTAGE BEINGS TO COME UP THEN SHUTS DOWN CHECK/REPLACE C916 (P/N# SBTP-0038)
JVC AV2556 N/A POWER SHUTS OF INTERMITTENTLY CHECK/REPLACE IC651 (AN7168) FOR LOADING DOWN THE 5 VOLT
JVC AV2590 N/A ARCING NOISE LASTING FROM 2 TO 5 MINUTES AFTER TURN ON - SLIGHT DISTORTION WHILE NOISE IS BEING HEARD CHECK/REPLACE C916 FOR OPEN
JVC AV2590 N/A RASTER WOULD FLASH AND SIZE OF THE PIX WOULD SHRINK CHECK/REPLACE C922 FOR OPEN
JVC AV2590 N/A DEAD SET WITH HIGH PITCHED SQUEAL WHEN TURNED ON - SOUNDS LIKE A SHORT ON B+ LINE CHECK/REPLACE Q503 (2SD871),C420 (470uF @ 50v), C915 AND C916 (1uF @ 160v)
JVC AV2590 N/A NO SOUND OR PICTURE - BUZZING SOUND FROM SWITCHING XFRM. - HIGH VOLTAGE BEINGS TO COME UP THEN SHUTS DOWN CHECK/REPLACE C916 (P/N# SBTP-0038)
JVC AV2590 N/A RETRACE LINES IN THE PICURE CHECK/REPLACE CAPACITORS INCLUDED IN KIT (P/N # SBTP-0038)
JVC AV2600 N/A NO SOUND OR PICTURE - BUZZING SOUND FROM SWITCHING XFRM. - HIGH VOLTAGE BEINGS TO COME UP THEN SHUTS DOWN CHECK/REPLACE C916 (P/N# SBTP-0038)
JVC AV2600US N/A PURITY DRIFTS CHECK TO SEE IF THE YOKE IS SECURE AND THAT TAPE AROUND THE NECK OF CRT IS TIGHT
JVC AV2600US N/A HORIZONTAL WHITE LINES ACROSS THE TOP OF THE PIX CHECK/REPLACE FR401 FUSIBLE RESISTOR OPEN
JVC AV2600US N/A ARCING NOISE LASTING FROM 2 TO 5 MINUTES AFTER TURN ON - SLIGHT DISTORTION WHILE NOISE IS BEING HEARD CHECK/REPLACE C916 FOR OPEN
JVC AV2600US N/A INTERMITTENT OR NO START-UP CHECK/REPLACE C916 (1uF @ 160v)
JVC AV2648S N/A BRIGHTNESS FLUCUATES INTERMITTENTLY CHECK/REPLACE IC201 (TA8601BNV)
JVC AV2648S N/A NO POWER CHECK/REPLACE D921 (P/N # MA165-Y)
JVC AV2651S N/A FAINT GREY VERTICAL LINE ABOUT 1/16' WIDE JUST LEFT OF CENTER CHECK/REPLACE IC101 (TA8725N)
JVC AV2690 N/A SET SHUTS ITSELF OFF INTERMITTENTLY AFTER WARMED UP CHECK/REPLACE RY01 (POWER RELAY P/N CE40134-001)
JVC AV2749S N/A SHORT VERTICAL SWEEP ON THE BOTTOM FROM 1 TO 2 INCHES CHECK/REPLACE DEFLECTION YOKE (P/N CE20179-OOAKJ1)
JVC AV2749S N/A DEAD SET - BLOWS B+ FUSE CHECK/REPLACE D1521 OR MAY BE MARKED ON THE BOARD AS D521 FOR SHORT
JVC AV2749S N/A AUDIO DISTORTION IN BOTH SPEAKERS CHECK/REPLACE Q963 FOR SHORT OR LEAKY (2SC1815Y,GR)
JVC AV2749S N/A DEAD SET - RELAY WON'T CLICK CHECK/REPLACE D921 (P/N# MA165-Y) AND Q921 (P/N# 2SC1959(Y)-Y )
JVC AV2750S N/A DEAD SET - RELAY WON'T CLICK CHECK/REPLACE D921 (P/N# MA165-Y) AND Q921 (P/N# 2SC1959(Y)-Y )
JVC AV2750S N/A DEAD SET - BLOWS B+ FUSE CHECK/REPLACE D1521 OR MAY BE MARKED ON THE BOARD AS D521 FOR SHORT
JVC AV2750S N/A NO TINT CONTROL CHECK/REPLACE C312 FOR LEAKY OR SHORT
JVC AV2751 N/A NO VERTICAL SWEEP - MAY BE INTERMITTENT CHECK/RESOLDER CONNECTIONS ON IC421 (LA7838)
JVC AV2759S N/A NO POWER CHECK/REPLACE F961 AND IC661
JVC AV2759S N/A DEAD SET - RELAY WON'T CLICK CHECK/REPLACE D921 (P/N# MA165-Y) AND Q921 (P/N# 2SC1959(Y)-Y )
JVC AV2771 N/A NO HORZ. SYNC CHECK/REPLACE D523 (P/N # 1SS133-T2)
JVC AV2771S N/A NO PICTURE - BLACK SCREEN - OSD IS OK CHECK/REPLACE IC831 (P/N# MN12C261D)
JVC AV27720 N/A BUZZING OR MUTING OF THE AUDIO ON SOME CABLE CHANNELS ADD 47pF (QCS31HJ-470AZ) FROM THE BASE OF Q161 TO GROUND
JVC AV27730 N/A BUZZING OR MUTING OF THE AUDIO INSTALL KIT # TPCD-0002
JVC AV27730 N/A HORZ. WIDTH SHRINKS AND PICTURE GETS DARK CHECK/REPLACE L531 (P/N# CELL009-003)
JVC AV27750 N/A BUZZING OR MUTING OF THE AUDIO INSTALL KIT # TPCD-0002
JVC AV27750 N/A HORZ. WIDTH SHRINKS AND PICTURE GETS DARK CHECK/REPLACE L531 (P/N# CELL009-003)
JVC AV27770 N/A BUZZING OR MUTING OF THE AUDIO INSTALL KIT # TPCD-0002
JVC AV27790 N/A BUZZING OR MUTING OF THE AUDIO INSTALL KIT # TPCD-0002
JVC AV2779S N/A NO PICTURE CHECK/REPLACE Q781 (2SC2785J,H -Y)
JVC AV2780S N/A WHEN TV IS RECEIVING STEREO BROADCAST, THE SAP LIGHT IS ON AND VICA VERSA. CUT JUMPERS W025 AND W026 AND CRISS/CROSS WITH INSULATED WIRE.
JVC AV27820 N/A SHUTS DOWN AT TURN ON AND TIMER LIGHT FLASHES CHECK/REPLACE T522 (P/N# CE42674-001J1)
JVC AV27BM6 N/A SET WILL NOT TURN ON WHEN COLD ADD 470uF @ 10v PARALLEL WITH C1913 (P/N# QETC1AM-477Z) AND REPLACE R1902 WITH 22k (P/N# QRD129J-223S)
JVC AV27BP3 N/A NO ON-SCREEN DISPLAY CHECK/REPLACE Q702 (P/N# 2SC1740S(QR)-T
JVC AV27BP6 N/A SET WILL NOT TURN ON WHEN COLD ADD 470uF @ 10v PARALLEL WITH C1913 (P/N# QETC1AM-477Z) AND REPLACE R1902 WITH 22k (P/N# QRD129J-223S)
JVC AV27CM3 N/A WHITE LINE THROUGH CENTER CHECK/RESOLDER CONNECTIONS ON IC421 (LA7838)
JVC AV27CM3 N/A POOR PURITY - PROBLEM HAPPENS ALL OF A SUDDEN AND NO LARGE MAGNETS HAVE BEEN CLOSE TO SET CHECK/REPLACE TH901 OR RESOLDER CONNECTIONS
JVC AV27CM3 N/A VERY INTERMITTENT SHUTDOWN CHECK/REPLACE RB507 (P/N# QRZ0091-009)
JVC AV3150S N/A RIGHT CHANNEL AUDIO IS LOW - LEFT CHANNEL IS FINE CHECK/REPLACE C673 FOR LEAKY
JVC AV3150S N/A RIGHT CHANNEL AUDIO IS LOW BUT LEFT CHANNEL IS NORMAL CHECK/REPLACE C673 FOR LEAKY OR SHORT
JVC AV3150S N/A RIGHT CHANNEL
JVC AV3150S N/A WHEN TV IS RECEIVING STEREO BROADCAST, THE SAP LIGHT IS ON AND VICA VERSA. CUT JUMPERS W025 AND W026 AND CRISS/CROSS WITH INSULATED WIRE.
JVC AV31BM6 N/A SET SHUTS DOWN FOR NO REASON - UNPLUGGING FOR 5 SECONDS OR ALLOWING SET TO COOL DOWN WILL ALLOW IT TO POWER BACK UP REPLACE THE HEAT SINK FOR IC901 WITH NEW TYPE AND APPLY SILICON GREASE (P/N# CEHT12B-001QS)
JVC AV31BP4 N/A NO VERTICAL SWEEP CHECK/REPLACE IC401 (P/N# LA7837 OR LA7838)
JVC AV31BP6 N/A SET SHUTS DOWN FOR NO REASON - UNPLUGGING FOR 5 SECONDS OR ALLOWING SET TO COOL DOWN WILL ALLOW IT TO POWER BACK UP REPLACE THE HEAT SINK FOR IC901 WITH NEW TYPE AND APPLY SILICON GREASE (P/N# CEHT12B-001QS)
JVC AV32720 N/A BUZZING OR MUTING OF THE AUDIO INSTALL KIT # TPCD-0002
JVC AV32730 N/A BUZZ OR HUM COMING FROM YOKE CHECK/REPLACE DEFLECTION YOKE (P/N# EC20317-00A)
JVC AV32730 N/A BUZZING OR MUTING OF THE AUDIO INSTALL KIT # TPCD-0002
JVC AV32750 N/A BUZZING OR MUTING OF THE AUDIO INSTALL KIT # TPCD-0002
JVC AV32770 N/A BUZZING OR MUTING OF THE AUDIO INSTALL KIT # TPCD-0002
JVC AV32790 N/A BUZZING OR MUTING OF THE AUDIO INSTALL KIT # TPCD-0002
JVC AV35750 N/A BUZZING OR MUTING OF THE AUDIO INSTALL KIT # TPCD-0002
JVC AV35770 N/A BUZZING OR MUTING OF THE AUDIO INSTALL KIT # TPCD-0002
JVC AV35790 N/A BUZZING OR MUTING OF THE AUDIO INSTALL KIT # TPCD-0002
JVC AV3589S N/A NO POWER - THE B1 VOLTAGE IS 0 CHECK/REPLACE IC602 AND C627 FOR LEAKAGE
JVC AV35BH4 N/A ELECTRICAL INTERFERENCE IN THE PICTURE CHECK/REPLACE LF903 (P/N CE41506-00AJ1)
JVC AV35BP4 N/A NO SOUND - PICTURE IS FINE CHECK IC601 OR MAY BE LABELED IC1601 (P/N# MC13516T2)
JVC C13711 N/A DEAD SET CHECK/REPLACE IC921 (P/N# STR-F6514)
JVC C13CL5 N/A SOUND MUTES INTERMITTENTLY ADD 15K?RESISTOR BETWEEN PIN 16 AND PIN 22 OF IC101
JVC C13CL5 N/A VOLUME CONTROL DISPLAY WILL NOT DISAPPEAR FROM SCREEN AND ON-SCREEN CLOCK STOPS ADD A 0.22uF @ 50v CAPACITOR BETWEEN Q250 COLLECTOR AND GROUND SIDE OF C007
JVC C13WL5 N/A VOLUME CONTROL DISPLAY WILL NOT DISAPPEAR FROM SCREEN AND ON-SCREEN CLOCK STOPS ADD A 0.22uF @ 50v CAPACITOR BETWEEN Q250 COLLECTOR AND GROUND SIDE OF C007
JVC C13WL5 N/A NO SOUND,COLOR OR PICTURE ON SOME CHANNELS CHECK/REPLACE IC703 (P/N# AT93C56-10PC)
JVC C2073 N/A NO SOUND OR PICTURE - BUZZING SOUND FROM SWITCHING XFRM. - HIGH VOLTAGE BEINGS TO COME UP THEN SHUTS DOWN CHECK/REPLACE C916 (P/N# SBTP-0038)
JVC C20CL5 N/A SOUND MUTES INTERMITTENTLY ADD 15K?RESISTOR BETWEEN PIN 16 AND PIN 22 OF IC101
JVC C2526 N/A POOR PURITY - PROBLEM HAPPENS ALL OF A SUDDEN AND NO LARGE MAGNETS HAVE BEEN CLOSE TO SET CHECK/REPLACE DEGAUSSING THERMISTOR OR RESOLDER CONNECTIONS
JVC C2693 N/A NO SOUND OR PICTURE - BUZZING SOUND FROM SWITCHING XFRM. - HIGH VOLTAGE BEINGS TO COME UP THEN SHUTS DOWN CHECK/REPLACE C916 (P/N# SBTP-0038)
JVC CAMXS4BK N/A WILL NOT DISPLAY TUNER FREQUENCIES AND WILL NOT SWITCH TO OTHER FUNCTIONS CHECK/REPLACE IC201 (P/N# HD614089SD51)
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PostPosted: Fri Jan 25, 2008 9:38 am    Post subject: Reply with quote

Thanks Graviyboots for all the Jbc problmes & solutions, so about the JVC Av-21FMG3B I have changed the Str coz it was shorted, I just changed it & then i was having this problem ? The STR is new ? Can it be the fault ?

And also when i changed a capacitor 25v 1000uf in the secondary near the transormer the voltage is now 120v on the collector of HOT but it still reduces 1 by 1 to 84v so tell me about his plz & does it have a problem if i simply mount the Horizontal transistor with the voltage 120v on the collector ?
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