Ron.M
Veteran
Feb 10, 2010, 12:31 AM
Post #9 of 14
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Re: [m103368] hitachi 50fx18b horiz compress
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m103368;.... OK , that sounds like good news.... I hope you followed this advice;=>.. IF you see ANY changes while doing either of the above 2 steps , STOP IMMEDIATLY... If you continue to aggravate the problem , you can cause further damage.... IF you did , we/you're in luck..... What you have is a bad PC connection/s at or near the Vertical output IC....(LA7838) Leave the TV off & UNPLUGGED overnight BEFORE you start.... That allows for safe discharge of unsafe voltages... You need to remove the board in such a way that you can flip it over upside down to see & get at the connections.... You should be able to do that without disconnecting the 4 heavy red wires coming off the Flyback... In the pix below , the heavy lines represent wiring you need to disconnect.... Except the flyback...That will hold a charge that will put you on the Space Station or beyond.... Do not forget the smaller jumper type connectors (6 of 'em) going from this board to the one on the left side... Do NOT force these as they can be easily broken...If you need help with these , please post... Unscrew , if any , screws that hold the board down... There may be some plastic clip/clamps holding the board down.... The large "heat sink" on the right side (For the convergence ICs) may have screws holding it in place... Also check around the flyback for screws holding it in place..... Once the board is free , try to set it upside down so the vertical IC is towards the rear of the set for easy access to the connections.... Use care doing this as the weight of the flyback & the heat sink with the ICs make for a flimsy manuever to do...The PC board is quite flexible & can be easily cracked ...USE CARE !!! After you re-solder the Vertical output IC connections , PLEASE do the flyback connections also...Just precautionary.... The 2 links below are for soldering lessons which may or may not be of interest to you.... One paragraph is important...This one;=>... A good connection is one where the solder has uniformly flowed over all the surfaces to be connected, following their contours. The connection appears bright, shiny, and smooth, with all wires in it appearing well soldered. However, if the connection is rough, grainy, or flaky looking, or if the solder formed into little round blobs, or has ridges or sharp points, redo it. Take the time to visually check the connection with those points in mind. If the joint is a "cold" connection, caused either by insufficient heat, a wire moving, or foreign matter (such as oxides) getting into the connection, the cure is simple and direct: re-heat the joint and apply a little more solder. If that would place too much solder in the joint, you will have to remove the solder before trying again. If you do have enough experience , skim thru the 2nd link.... One thing about soldering;..Do not leave the soldering iron tip on the connection for too long as the heat can lift the foil off the board & possibly damage it.... When you solder the vertical IC , notice that the pins (13 of those) are very close together.... Use care not to have any solder bridges between any of the pins or you WILL blow something when you turn on the TV... Use a magnifying lens or glasses & check for bad connections around the Vertical IC & repair those that look suspicious or are bad.... Reinstall the board & all connectors.... Send email to your religous leader (IF you have one) & ask for all their help......... Turn on the TV.... Watch the board first (NOT the screen) for any smoke or overheating parts in the area you worked in.... If nothing seen , check the pix.... Post back with results.... http://www.pc-control.co.uk/soldering.htm http://www.elecraft.com/...SS_SolderNotesV6.pdf HAVE FUN & GOOD LUCK......... Also , PLEASE answer this;=>... ""Can & are you able to take & post pix in case they're needed ???"" Just in case...... Thanks... IF you have problems getting the board out , turning it over , etc , STOP & post... OR any other problems.... I will answer asap.... Later...Ron.M........ Veteran & Retired TV technician
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