Re: SharpLC 52D64U Signal kills backlight
Thanx for the reply. The power supply voltages seem fine when the set has no input from the tuner or VGA inputs (did not have equipment to feed HDMI inputs in the field). Did not check them when it shuts down the backlight. Good thought though. If the 60volt feed shuts down, that would explain alot.
I doubt this is the case. I think the control signal to the inverters (like from the TCON as is typical in many sets) is turning them off.
I downloaded the service info online. I will check to see if there is any...
G Nicholls
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Last Activity: 09-13-2015, 05:26 PM
Joined: 02-23-2010
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SharpLC 52D64U Signal kills backlight
I am servicing a Sharp LC 52D64U. It is similar to the 42, 46, 52, & 65" models in the D64 series. The board views and service manuals are in existing posts.
This unit had a typical backlight failure: a pair of shorted MOSFETs on the slave inverter board. {J655 and K3706} I ordered up IRF539N and IRF9530 from Jameco that are 100V 17A rated N & P channel replacements. The repair seems fine, BUT ONLY WHEN THE UNIT IS IN "MENU" MODE OR WITHOUT A SIGNAL INPUT IN THE OTHER MODES.
So, the unit is fine when processing it's own generated "video"... -
LG 37LD450 no power-up
I am having trouble tracing the problem of a LG 37" LCD TV with conventional backlights. The power supply is providing the proper voltages to the main board. 20V, 12V, and 3.5V. also, the power on line goes to 3.23V when the power on button is activated.
I suspect a problem with the main board. I disconnected the inverter on line at the main board and supplied it with 3.3V. The inverters lit the backlight for about 2 seconds, and then shut off. It seems the main board never attempts to supply the inverter on voltage.
This TV is a bit newer than most I have salvaged,... -
Re: emerson LC320EM9 Blinking power light
By golly, that was budm.
Well, thanks to both of you. I sure learn well from your shares. Great community here. Barkeep...another round for my friends!
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Re: emerson LC320EM9 Blinking power light
I am also repairing a Emerson LC320. Thanks to tom66 for posting the service manual.
My unit has all the correct voltages at CN301 as advised in the prior post. However, there is no 3.3 volts present at CN301 pin #3 (backlite sw.) So, no successful power-on-self-test. The 30 volts for the inverter never cycles on.
Visual inspection of all boards O.K. Pulled and checked the 30V section caps with a ESR meter. O.K. Checked all power section diodes for open or shorts. O.K. Did a basic check on the 30V N-Channel...Leave a comment:
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Re: Vizio VX37L TCON Transistor ID please
Mornin' Budm. I pulled the working TCON board and checked the good Q303. Part number ia 25727 on this one (must be a in house number). In diode test mode the meter shows infinate across all lead combinations except base to collector. That shows .534 with the + probe on the base and - on the collector. That is within the typical forward bias range this meter shows on diodes and transistors.
I wonder if this is a complex transistor with a zener diode trigger or some other exotic design. Don't know, so I buttoned-up the unit...Leave a comment:
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Re: Vizio VX37L TCON Transistor ID please
Thanx, budm. I realize I may be able to try to hack a fix to this TCON. I was hoping someone might know the correct cross reference or a known substitute.
If I repair this TCON and turn it out, I would not like it to bounce-back due to a too marginal repair. Can you tell what function this transistor preforms? I was not sure if this was a switching or timing circuit. Could make a difference in the selection of a replacement.
Thanx for all your participation at the site. I have learned a lot of great...Leave a comment:
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Vizio VX37L TCON Transistor ID please
I am repairing a Vizio LCD TV TCON board. I am unable to find a cross reference or data sheet for a failed semiconductor. The part is not referenced in the service materials referenced on this site. So, I an unable to select a suitable replacement. The TV model is the infamous VX37L HDTV 10A. It has the AU Optronics panel and TCON board.
Model on the TCON is: TS-5337T03021-740-NE40000. The offending part is Q303, part number engraved is: 25709. It has a base to collector short. Base polarity is negative (continuity to the ground plane of the board). I have lots of various scrap... -
Re: Samsung LNT4669FX/XXA dark on one side
I worked on a Samsung 46" LCD mfg. in 2008 this past week. Flexing the frame slightly confirmed a "bad tab bond".
Removed the plastic front bezel. Then removed the metal frame from the LCD panel to expose the mylar film tab conections.
Confirmed the display's top right-hand-side mylar film connection was flakey with the set powered up.
I placed a 1 inch strip of closed-cell foam tape on the offending bond. I replaced 3/4 of the width of the paper that covers the adhesive back...Leave a comment:
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Re: KDL40s4100, no picture or sound
Opsie!! I feel a bit dumb. I went back looking for this schematic again. At the bottom left corner of the page is a small reference to download the manual. The site works. Excuse my prior post. Thanx bigdozer. I humbley stand corrected. (But there sure are a bunch of "diversions" on the site to hoodwink a novice.)
Giddiee-up!!...
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Re: KDL40s4100, no picture or sound
ELECTROTANYA...Scam download site! No schematics, only crapp "buy me" stuff!
badcaps is a great site. Do not let this re-direct sour you on the site. Great info here.
Thanx to the moderators.Last edited by G Nicholls; 01-11-2012, 08:44 PM.Leave a comment:
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Samsung Syncmaster 570 STFN image issue
I am having a screen image issue with this LCD monitor. This is a real "old dog" with a external 12V supply, so many of you will not have seen many of these. The problem is best described as a sync or timing issue.
There are horizontal lines interlaced evenly with the image lines.
These images seem to behave a bit like a slowly rolling image on a analog TV screen when the vertical sync is not locking.
There is a "herringbone" artifact moving thru the entire screen image.
The video image is set to 800X 600 60Hz. No LCD select...
No activity results to display
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