The sound has become very low and crackly, and when I add external speakers, I get crackling and/or a big squealing. It worked fine until 3 days ago model T61 7662 CTO

They speakers are broken and no longer working and need to be replaced.

I do also get this same issue, They were working just fine, and 4 or 5 months ago, the right speaker crackles, if i unplug the right speaker all is fine. But as soon as I plug the right speaker in, i get a cracking sound. Have you solved this ussue?

I have the exact same problem. It's a volume control issue. For me, when I turn my TV on and have it on low volume, it works fine (but sounds somewhat distorted). But once I turn the volume up to normal levels, the speakers crackle and then go out. I opened my tv and checked my speakers, and they were perfectly fine; not blown or anything. As well, the audio processor and circuitry didn't appear burned at all.
This used happened every few months for 30min or and hour at a time. Then, about 2 months ago, it happened again, and ever since then it still hasn't worked properly. The only way I got around this was by buying a cheap 2.1 speaker system, and connecting it to the audio output on the TV. Or you could buy a speaker bar or home theater system. I believe this issue has to do with problems with the circuitry in the audio amplifier, and there's not much you can do except add external speakers, or contact Sanyo if you still have an active warranty.
Depending on where you bought your TV (such as from walmart), its possible that the LCD panel was produced by Sanyo, but the electronics were done in China. Walmart does this with nearly every TV they sell.

Sounds like a blown speaker. If you wan to test the sound card try using external speakers. If you still get the crackling sound then it's your sound card. Hard to fix in a laptop.

There are several reasons why you could suddenly be getting a crackling noise. My best guess is you have the laptop near some kind of magnetic source - maybe a cell phone? My Boost mobile phone would do this to my speakers. Is this possibly the cause?

Plug in your external speakers then go to system preferences then sound when in the sound control panel go to the output tab and select the external speakers as the device for sound output and of course at the bottom of the control panel make sure that the mute check box is unchecked and turn up the volume. Hope this helps

1. remove all external peripherals.
2. use the internal speakers
3. uninstall / reinstall the audio drivers
4. reboot system
5. if still hearing the crackling sound check if cracking sound can be heard only inside windows of even in the bios.
6. check bios hdd if in acoustic mode performance if yes then set it to normal.

maybe the problem is on the files you play but not your device.

The answer is: "Yes." If your speaker wiring is such that they all share a common ground wire, and that ground wire is shorting out, it can cause all speakers to go silent when it is grounded (shorted). I would check the wiring, and replace any cracked wiring, and if the wiring looks like the shielding is worn, replace all the speaker wiring. Monster cable is the best, but any heavy copper wiring works fine. I often use 110V. appliance wiring to install car stereos.

suggest,checking pwr point earth,power leads, try a different antenna,unplug any external connections not needed to recieve broardcast,shift position of tv by 3 mtrs. Regards Chook.