Question about Toshiba TP55H60 55" Rear Projection Television
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About 2 years ago I replaced the stk's (Q751 and 752) which worked till about 2 weeks ago when bent color horizontal lines started appearing intermittently in the middle top of the screen. Last week ,the picture died completely but the sound still works. I replaced the two power amps again(Q751 & 75) but had the same problem. Right now, if the remote is used to power and shut down the TV, the sound will not come on but if the power cord is unplugged then plug in ,the sound will come on but not the picture and also when the TV is turned off, a bright horizontal flash / line on the middle of the screen appears before it shuts off . I checked the power supplies and they seem to be good. I got bogged down by the fact that on pin 11 of Z801 and on pin 1 of P806, schematic says that I am suppose to get 24.7 VDC referenced to GRD and +38 (H.VCC) on pin 1 of P806( also referenced to chassis grd) but I was getting 0.0 volts. I don't see the secondary of the transformer directly referenced or tied to chassis grd so this made me doubt whether this is a printing error or valid reading. Help is appreciated, Thank you.
Highland Electrix TV Repair Advice no pic snd ok Page
Highland Electrix TV Repair Advice no pic snd ok PageNo picture, sound ok
First increase tube's first anode voltage (knob on the loptx) to see if the screen is just too dark.
if after you have turned up the bottom knob on the loptx, there is still no brightness,check, for crt heaters, and EHT 25kv and focus voltage (2kv) and A1's/Screen/G2 voltage is 300-600v.
and check for field timebase (height), the next thing to check is the sandcastle pulse.
If it's present, colour decoder chip is probably faulty or lacks supply from the LT regulators.
Posted on Jul 25, 2008
If everything else works - there is sound and high voltage (static on the screen) - but there is no picture (including no on-screen menus), this limits the likely area of problems is the video output circuitry or CRT filament connections. Check to see if the CRT filaments are glowing. If they are not glowing, check for bad soldering on the CRT neck board and around the flyback transformer. Where the picture is erratic - coming and going entirely or changing brightness suddenly, with power off, remove the picture tube socket (carefully!) and clean the pins with fine sandpaper and use contact cleaner on the socket. This source of bad connections can result in a variety of erratic symptoms. Check for bad solder connections on the CRT neck board
Posted on Jul 15, 2008
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