When I switch on the unit, i can hear the sound but there is no picture

Replace the power board and you should be back in business.

What is the make and model?

Well...as you said...the unit powers up...so you don't have a "dead set".I don't know if the speaker can be disconnected from the unit.As a rule of thumb...it is very rare that both channels (left and right )fail at the same time...it is usually one channel while the other speaker still operates.This is what I want you to do...In a quiet room..get really close to the unit...Switch it on and listen for any sound from the speakers...get really close...you should hear a slight hum from the woofers and a high frequency "hiss" from the tweeters....If no sound is heard..switch the unit off..You should hear a "plip" sound...If not...switch it on again...you should hear a slight "bump" sound from the woofers...If you hear no sound from the speakers at all..there is a problem with the output stages of the amplifier section.If you do hear sounds fron the speakers,,Turn up the volume and watch for an increase visually on the display (such as ascending numbers).If there is no indication of a volume increase...The "mute" may be stuck on..Try switching it off and on...please let me know what happens after you do all the tests....Looking to hear from you......PEACE!!!
ok...

I assume you are talking about a storage heater here. Most of these unit have a small trickle switch underneath or close to the thermostat switch that may need to be reset manually. Once you push the small switch you will hear a click sound which resets the unit and the heater should work as normal. It is a bit hard for me to pin point where exactly it is located but if you get back to me with a picture then I can help further. Good luck and if you have any question please feel free to ask but allow me some time to reply. Thanks.

without consulting my crystal ball for the type of tv and its features, check rear of unit for external speaker switch, speaker output setting in menu, etc. possible hardware faults include , faulty headphone socket not switching speakers on, faulty speakers etc.

Hi,
You need to park your car to see picture in screen of Sony XAV-A1 because its engaged with hand break/ parking switch in your car.

As you know during driving, it is unsafe to watch movie.
Let me know if you have additional question.
Thanks.

Sounds like a hard drive failure. Contact Dish Network for warranty/repair info.

If you hear a kind of hissing sound then is a faulty ballast

unfortunitly sound is one circuit ,,while all the rest makes a picture. hearing a bang could mean a capacitor exploded, your fly blew up..or even you lost a tube. you need a tech. good luck

Possible problems: * The TV set may be unplugged. * A fuse or circuit breaker may be blown or switched off. * The remote control unit (RCU) may be disabled. Solutions: * Make sure the TV/VCR are plugged in and the wall switch is on. * Check the fuse or circuit breaker. Test the outlet with a lamp. * Replace the RCU's batteries: if this fails exchange the unit.