Spectroniq PLTV-42HW68 TAKES 3 TO 5 MINUTES TO COME ON AND POPS THROUGH THE SPEAKERS SOMETIMES YOU GET SOUND BUT NO PICTURE, TURN SET OFF FOR 10 SECONDS SET COMES BACK ON AND PLAYS ALL DAY

basically it is input issue Brent, you may want to turn off and on your tv after 4-5 minutes, if same thing press on your tv remote INPUT, SOURCE or TV/VIDEO and you should have input lists on your tv screen. Choose one by one until you got a picture.
You can also check this out.

sounds like it is over heating. in side the tv there is 2 square box cannot remember the colour but they are yellow or blue near to a heat sink chip. if you change them it may just be that fault. Bush tv's suffer from this problem.

take it to a service center

is it the picture or the back light ? does the screen go white or darken. ?

There is only one power supply module, see here: http://www.shopjimmy.com/catalogsearch/result/?q=PLTV-42HW68

Or try EBAY.

Basic LCD monitor and TV troubleshooting guide:
http://www.fixya.com/support/r5093881-lcd_flat_panel_tv_troubleshooting_guide
http://www.fixya.com/support/r6150077-basic_lcd_monitors_troubleshooting
http://www.fixya.com/support/r7406380-tv_training_manuals
Failed TV and Monitors: http://s807.photobucket.com/albums/yy352/budm
Learn about bad caps: http://en.wikipedia.org/wiki/Capacitor_plague
Parts: www.shopjimmy.com
Capacitors kit: http://lcdalternatives.auctivacommerce.com/Default.aspx he can make you a set of caps.
Or www.digikey.com, just make sure to use caps with low ESR, 105c, high ripple current and long life rating such as PANASONIC FM or FC series.

Brand: Spectroniq

Most likely code: 11523

Let verify first to narrow down to where the problem can be. First, check the on screen sound set up menu to make sure the speakers are not set to OFF. If the setting is OK, then attach the powered PC speakers to the Audio Line out RCA jacks to see if you can get the sound there, if you do, then the problem can be in the power amp circuits, if you do not get the sound at RCA jacks, then the problem can be in the sound processor circuit. Please post back what you find.

Are you sure it is Spectroniq?
http://www.shopjimmy.com/catalogsearch/result/?q=PLTV-42HW68

I have a Spectronic LCD HD 42 "color screen is black with bright colors, sometimes does not look good, it lacks definition to see.

There is only one person I know of that could help you with this

Frank Z. SR
Audio-Tronics
Cherry Hill NJ
Phone 8566670160
open 10-5 m-f 10-2s sun closed