Question about Hitachi 50GX49B 50" Rear Projection Television

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50ux22ba no power open back all green light come on and then go off. red led says on. none the diodes or resistors look burnt,fuses okay. thank you john

Posted by jmaggio2 on

  • 2 more comments 
  • jmaggio2 Oct 11, 2007

    can not find e994 have seen pic but does not seat there. and c702 found

  • jmaggio2 Oct 11, 2007

    turned tv on. it worked but wave line, also does not alway come on,

  • Driftindale Dec 05, 2007

    Had same problem. Found C708 was bad. Cant find cap anywhere. Was wondering if you guys could point me in the right direction? Part number is... 0262414F

  • Idanno Feb 21, 2009

    i also have the same problem and cannot find 994 or 707 anybody know about this problem

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Common failure is C702 Capacitor near flyback== 102K/2KV shorted==replace w/102K/3KV generic or Sony part number 1-161-754-00.Also,check E994 open 2 amp pico fuse.

Posted on Oct 09, 2007

  • Vista Electronics Oct 11, 2007

    Check all soldered in pico fuses,(usually light brown color)



    may not be E994 in your Model/chassis.Look in power supply area where regulators are.

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50 Emerson LED LF501EM4F will not power on. No standby light.


Hi. Please check that the power cable is okay. Then, open tv and confirm that the fuse is okay. If fuse is okay then power board has an issue. It could be a capacitor,resistor,diode or ic. If fuse is blown, do not replace it before the tv is checked to prevent more damage. To know whether tv has a short circuit or power board has a fault, Get a 60 watt filament bulb and remove damaged fuse then solder some wires to the two bulb termini and solder the two ends at the two points on the fuse and power the tv. If the bulb come on and goes off then the power board is okay because this signifies that a circuit is complete. If the bulb goes on and does not go off then it means that there is an issue and the circuit is not complete. Under state 1 replace fuse and power your tv and it has to go on. Under state 2 please have a qualified technician check the power board.

Nov 15, 2016 | Emerson Televison & Video

Tip

Shorted Rectifier Diode (fuse keeps blowing)


jdvillanueva_14.jpg
This CRT tv is dead set, no reaction when the power button is pressed(no standby led light). I've open the back panel and check the faulty parts.
jdvillanueva_15.jpg

As you can see the fuse was badly burnt-out indication of excessive current due to short circuit.
jdvillanueva_17.jpg

I've checked the parts feeding the AC line to the power supply board (Power cord, VDR, Ceramic capacitor, Coil, Posistor, Degaussing coil) one by one and I've found out that one of the four rectifier diode has a leak which caused the glass fuse burnt-out.
Here's how to test the rectifier diode.

Good Diode
Note : Forward and reverse bias depend on what type of ohmmeter are you using, here I'm using a Japan Standard(Sanwa Brand).
jdvillanueva_21.jpg

Using an ohmmeter set it to X10 to see much easier the leak from the diode in reverse bias.

Forward Bias : test the diode by connecting the red test prod of the tester to anode and then the black test prod to cathode of diode. You will see the pointer will reads a faily low resistance(above picture).
jdvillanueva_22.jpg

Reverse Bias : test the diode by connecting the red test prod of the tester to cathode and then the black test prod to anode of diode. You will see at the picture(above) that the pointer didn't react (remains in infinity). This is a good diode.


Bad(leaky) Diode
jdvillanueva_23.jpg

Forward Bias will reads fairly low resistance.
jdvillanueva_24.jpg

Reverse bias unlike the good diode the pointer will also reads a fairly low resistance.

After confirming that the diode caused the fuse from blowing I've decided to replaced all four diodes since I have a lots in my stocks.
jdvillanueva_25.jpg

Remember that when you installing the new diode on the board, make sure that you will make it in the right polarity.

jdvillanueva_26.jpg

This steps is also applicable in the DVD Player,Flat panel, Projection, LCD TV, you have to disregard only the posistor and degaussing coil.

Have a nice day!
Thanks for using Fixya.

Jdvillanueva

on Mar 02, 2011 | Televison & Video

1 Answer

Tv will not power on!!!


most likely will need a new power supply, google it

Jan 01, 2010 | LG 32LG30 32 in. LCD HDTV

1 Answer

Can,t get it to turn on.


Does the red light come on? does it go green but no picture? Here are few possible solutions:

If you have no red light and you have a Megmeet MLT386 power supply, check these parts:

1) Swollen caps on the secondary circuit.
2) Blown fuse F1 (5A/250V) this is caused by a shorted FET at QA1 (20N60), you may also find that SMT cap CX23 is burned up (.001uf) which is in parallel with diode DA2 which may be damaged/shorted, replace these components.

If the power LED goes from red to green when powered up but no picture, then it might be lost +24VDC from the power supply:

3)Check fuse F2 (3.15A/250V, I put a 5A in), if it is blown, replace FET at QA2A (9N50C), replace QA2 as well (9N50C). Check SMT resistors at R233,R234,R235,R236 (.47 ohm). If open, replace with .1 ohm 1W or 2W resistor (easier to source). Also replace SMT transistor QF1 (2X4 or 2N4401 NPN transistor). And replace diodes at DS2 and DS1 (HER207), DS2 was shorted, DS1 was ok but I replaced it anyway.

I dont know as much about the Megmeet MLT169A, but it has similar problems and similar components.

4) I had to replace all of the capacitors in the secondary circuit (there are six in a 3x3 row marked EC9 (1000uf35V),EC10(1000uf35V),EC14(470uf35V) and EC18,EC19,EC20 (all 1000uf35V).

Sep 05, 2009 | Akai LCT3201TD 32 in. LCD Television

1 Answer

TV won't turn onthe red light just blinks when I push the power button.


I think this might be bad/swollen capacitors, or something odd in the +5VDC circuits of the power supply, but I am posting all of the things I have found so far with these TVs.

Here are few possible solutions:

If you have no red light and you have a Megmeet MLT386 power supply, check these parts:

1) Swollen caps on the secondary circuit (may cause the red light blink problem).
2) Blown fuse F1 (5A/250V) this is caused by a shorted FET at QA1 (20N60), you may also find that SMT cap CX23 is burned up (.001uf) which is in parallel with diode DA2 which may be damaged/shorted, replace these components.

If the power LED goes from red to green when powered up but no picture, then it might be lost +24VDC from the power supply:

3)Check fuse F2 (3.15A/250V, I put a 5A in), if it is blown, replace FET at QA2A (9N50C), replace QA2 as well (9N50C). Check SMT resistors at R233,R234,R235,R236 (.47 ohm). If open, replace with .1 ohm 1W or 2W resistor (easier to source). Also replace SMT transistor QF1 (2X4 or 2N4401 NPN transistor). And replace diodes at DS2 and DS1 (HER207), DS2 was shorted, DS1 was ok but I replaced it anyway.

I dont know as much about the Megmeet MLT169A, but it has similar problems and similar components.

4) I had to replace all of the capacitors in the secondary circuit (there are six in a 3x3 row marked EC9 (1000uf35V),EC10(1000uf35V),EC14(470uf35V) and EC18,EC19,EC20 (all 1000uf35V).

Aug 10, 2009 | Akai LCT3201TD 32 in. LCD Television

1 Answer

57F500A, powered light on with no sound/picture, ticking noise


Over the years of servicing these sets and others for Convergence issues, I have on several times gotten defective Convergence ICs. In your case where a Resistor is now open, (Probably a 1.5 ohm 1/2 watt), I would suspect you had gotten a hold of a defective IC. I would replace them both again. Make sure to use Heat Sink Compound between the ICs and Heat Sink.(Just a thin coating on the metal area) You can get the heat sink compound from Radio Shack. They should also have the Resistor you need.
Good luck,
Skyassoc

Jul 23, 2009 | Hitachi 57F500 57" Rear Projection...

1 Answer

Low voltage power supply problem


Hi, I agree that the regulator IC is probably toast but you`ll need a service manual to figure the rest because none of the leds are on which means NONE of the secondary supplies are running, check the chemical fuses and I`m sure some will be open. you can go to encompass parts on the internet to order the sm, trust me you`ll fix it a lot faster, gl, video-tek

May 31, 2009 | Hitachi 55FX20B 55" Rear Projection...

2 Answers

Tv won't turn on


yes but you have to open the tv

Mar 01, 2009 | Loewe Aconda ACO9303 30" TV

1 Answer

Non working TV, can someone help???


Replace Q8023 (top224y) which you will find is blown apart or it's shorted, and the Q1 (2sk2662) which would check to be shorted inside the heat shrinked wrapped board next to the blue relay and the smd zener diode ZD8018 (shorted) along with the ceramic fuse F8001.
I don't remember the value for the zener diode but there's lots of them with the same color code. You will have to take one of the others off to test on a resistor jig to get it's value.
The 2SK2662 is a cross for the original.

Nov 29, 2007 | Electrograph Systems DTS42W 42 in....

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