Toshiba 40RF350U won't power up, yellow light flashes 3 times but no picture comes up, it just repeats flashing the yellow light.

Hi Karen, The link below is a YouTube video showing how to fix a Toshiba television NO picture GOOD sound, Also there's videos down the right side of the link that may help as well........CHEERS..
https://www.youtube.com/watch?v=WtRuUBS9doE
Toshiba 55HT1U repair No Picture

The chances of the ballast failing are small on this model. Count how many times the Yellow light flashes before it pauses. Then google 57HM167 and the amount of blinks. ie " 57HM167 Yellow light flashes 3 times" That will tell you what you need to know. You can also post it here and we can help. I suspect you have a stuck fan(the fans are monitored to see if they are spinning. If not, they will not allow the TV to start up). Or you have the cover for the lamp not installed all the way. There is a switch that the lamp cover activates and the the TV will not turn on without it secured.

check some leak or bulged capacitors at the power supply board then replace it.

Toshiba Regza 37in - 37HL17
TV will not turn on - Yellow power ind. Light blinks three times...
Fixed with a firmware update (hard to believe, but true). Search Google for a file named: 2007SEN069.zip (don't worry if the page you find it on doesn't mention the 37HL17 - it worked fine). Unzip the file, and copy the 3 folders and 3 files to the root of a small SD card. The SD card MUST be 2GB or less in size (I used a 1GB card), and it MUST be formatted with FAT-16 (not FAT-32). Mine was pre-formatted as FAT (FAT-16). The SD port is on the back of the TV behind a cover plate near the power cable. You do NOT need to remove the back cover of the TV, just the small cover plate (1 screw). UNPLUG the TV; remove the cover plate; insert the SD card (prepped as explained above); Plug in the TV; Watch the yellow lights blink, then turn blue, then go dark; UNPLUG the TV; remove the SD Card and replace the cover; Plug in the TV; Yellow lights will blink a few times (this is normal); when blinking stops, turn on the TV and you should be good to go. :-)
Pictures attached are from a Toshiba software upgrade bulletin I found online.

Hi bcastlep...
Remove the battery for 3 minutes, then replace it.
That should solve your problem.
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This is software problem Call me at 905 6021613

My KV34HS510 Led flashed 4 times then stops for a few seconds and repeats. Is this the D Board MCZ3001D IC problem?

bad sein pcb

turn tv on picture comes up 2to3 seconds later tv blacks out then stand by red light flashes 4 times in a row repeatedly..can not turn on or off when stand by light starts flashing but before tv blacks out you can turn tv on and off repeatedly and picture and sound work.You have to unplug power cord for 30 seconds after stand by light comes on to get tv to turn on.

TV tries to come on - yellow light next to power light flashes but then it turn itslef off.........It tries agin after few sceonds and sequence repeats. I can hear the sound but no video