Won't work on ac

On the power pack there may be a label that says 12v dc or 18v Dc or some other voltage. There may be a input voltage on the keyboard and a current rating eg 12v DC 1A current or it might be AC voltage of 12V or some value.

get a volt meter or a multimeter and measure the voltage on the plug. positive is the inside part and the outside part is negative. dc setting if dc volts expected or AC setting for if AC voltage expected
Or get power pack tested at a music shop you may have a faulty power pack

Hi

Input: 120VAC 60Hz 35W
Output: 12VDC 1.6A

Source - http://www.ebay.com/itm/Homedics-AC-DC-Adapter-Model-ADP-8-D12-16-P-02-12V-1-6A-Power-Cord-Wall-Plug-/111507454421?pt=LH_DefaultDomain_0&hash=item19f65cb9d5

I hope this helps :)

Check the adapter itself bow out, when it is plugged to Wall AC socket. Do not load it to TV, and check this. If it blows up, the fault is with the adapter itself. If it don't, the fault must be within the TV circuit.

1) You need to look at the output current rating (AMP) of this AC to 24dc adapter, this 24vdc adapter is a regulated switching power supply that will maintain 24vdc output up the maximum current rating and also has shutdown circuits if the over current draw is detect and also if the output voltage goes up beyond 24vdc to protect the load (TV).

2) To use 12vdc to 24vdc DC-DC booster, it should have the following spec:

A) The output current rating should be at least 20% higher than the load requires to give its head room.
B) It must have regulated output that will maintain the 24vdc when the input (12vdc) will vary from 10vdc ~16vdc or higher since your batteries will not maintain exact 12vdc all the time.
C) It must have good protection circuits that will protect it self from reverse polarity connections, shorted output protection, over voltage output protection.
D) It should provide AC ripple spec on the 24vdc output, it should be in the milli-volt range (you will always get AC ripple riding on top of DC when you rectify the AC into DC).

These are the minimum requirement for your DC to DC booster, which you need to protect your TV and your motor home from burning down.
I hope I explain it OK to you.

Please leave rating if it helps.

Basic troubleshooting guide here:
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, long life rating such as PANASONIC FM or FC series.
Please leave rating if it helps.

What is the current output of the adaptor? If it is AC and you use only the 12v to 3v it is ok. But if the current output of the adaptor is DC and you use both 24v to 6v and 12v to 3v there is some danger if use the new one. Remember that DC current have polarity.

Have you checked the fuse in the plug on the end of the DC power cord? Just unscrew the end.

Actually i haven't fixed the problem as yet but i did find some info that would help me to fix problem.
I went to google and entered keyword,,, Electronic parts,,there came up a page,,and i went to several manuf sites till i found a replacement transformer,,then i disassembled the power supply and am now waiting for a replacement transformer.

This system uses in conjunction with the transformers a rectifier which converts the High AC current voltage (220V-AC) to a Low AC current voltage (12V-AC) and then the rectifier converts that energy into the D/C current (12V DC). The two diffrent 12V power sources are controlled, operated by a "electric" relay, via a roadside or electric selector switch. DS_TK TECH

AUTOMATIC AC/DC CHANGEOVER: All Engel Fridge Freezers can be plugged into both AC and DC at the same time. The Engel is smart enough to use the AC while available and then automatically switch to DC when the AC is no longer working. It will also sense the resumption of AC power and automatically switch back to AC making it ideal for high hurricane areas and places where power disruption is common.
Read more: http://www.roadtrucker.com/engel/engel-12-volt-fridge-freezer-technical.html#ixzz2MvRL2xrC

Are you certain the polarity of the connections to the TV are correct? If you connected them in reverse you may have damaged the TV. If there's a fuse in line check that too. BMW