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I have a Panasonic model# sa-dk2 home theater system that will no longer turn on. I think it’s the transformer, however this unit contains two - would you know which one it would be?

I have to admit up front that home theater is not really my area of expertise. That said, I did a little digging and did come up with some possibilities about what is causing the power failure on your system.

My guess is that your Panasonic SA-DK2 home theater system is more than about five years old and is no longer under warranty. That said, there really are no user serviceable parts inside, so anything I tell you is not really a green light to get in there and go digging around - some things are best left to professionals both for the sake of your system and your safety. You can find some information on the SA-DK2 on the Panasonic website  where you can download a user manual and find a Panasonic servicer near you.

Check the Source

Before we go straight for the transformer as your likely suspect, have you ruled out all of the obvious culprits first? You’d be surprised at how many people think that their equipment is faulty when it is the power source that has tripped. Plug in a lamp at that outlet and make sure that it is working properly first. Do the same with any surge protectors you are using (you are using surge protectors on all of your electronic equipment, right?) and make sure that the outlet that it is plugged into is good.

Check the Fuse

I couldn’t get too much information on your particular model, but most often it is a fuse rather than a transformer that is the culprit in home theater power failure. Most transformers have an internal fuse that prevents the equipment from drawing too much power. It is rare to have a transformer go bad without blowing the fuse first, and a blown transformer will likely generate a lot of smoke - it would probably be hard to miss.

You should be able to test the transformer using an inexpensive ohm meter. With the meter on the lowest scale, you can test each winding of the transformer to see if you can spot a problem.

Again, I don’t recommend delving into the innards of your home theater unless you have a real expertise in that area, but this will hopefully give you some ideas about what the problem might be.

I have recently changed the case of my newly built pc. It worked perfectly before the change but now won’t switch on. I have tested the PSU and it works fine. I previously believed I had shorted out the motherboard, so bought a new one and fitted it, but still it won’t turn on.

Without knowing some specifics, we’re going to have to do a little troubleshooting in order to narrow down the cause of your power up problems.

Motherboard Issues

Do you see anything when you try to turn it on? Any lights, fan noises, etc.? My bet is that it is either incompatible RAM or a problem with the actual power button setup. You say the PSU is fine - did you test the motherboard and PSU setup outside of the case? It’s possible that you are shorting the motherboard somehow within the case. Some motherboards have another 4 position power connector from the power supply to the motherboard in addition to the 20 or 24 position main connection. Make sure that connection is plugged in if you have it.

Power Switch

So many times, it is the power switch connectors themselves that are causing this type of problem, particularly with a new case setup. Make sure that you are connecting the case power switch wiring correctly - check with the manual, as sometimes the markings on the piece itself can be misleading.

Incompatible RAM

Is it possible that the RAM isn’t compatible with the motherboard? You can check for compatibility issues by removing the AC power to the power supply and then removing all RAM. Make sure the speakers are connected so you can hear beeps. If the motherboard has onboard sound, you must connect the speakers to the Line Out port and make sure they are turned on. Now, restore the power to the power supply and boot up the computer. If the RAM is the problem, you will hear a pattern of beeps that say there is no RAM installed.  If the RAM is incompatible, then you will need to do some research to find some that is compatible with your new motherboard.

I think that checking these few things will help isolate your issue. If you need additional help, please let us know.

From the limited amount of information I have here, I’m thinking that this is a hardware problem rather than a hard drive issue. There are a few things you should try in order to determine where the problem is originating.

Check Your Power Cord

Sometimes, your laptop looks like it’s charging, but it isn’t. Is there a light on the front of the laptop that goes on when you plug in the power cord? If you’re not sure, you could get a multimeter and check the power supply. If the cord is bad, you can simply get a new cord and you should be good to go.

Check the Power Flow

It could be that there are too many items on your computer competing for power at start up. Try to check for that by following these steps:

1. Unplug the laptop and remove the battery.
2. Press the power button a few times to discharge power to the capacitors.
3. Make sure your RAM isn’t loose (see below).
4. Unplug every peripheral, then power it up with a working plug.

If this works, try plugging in the peripherals one at a time and see if the power holds.

Reseating the RAM

If you RAM has come loose, your computer won’t be able to power up. Follow these steps to make sure that your RAM is secured in place:

1. Remove the battery from the bottom of your computer.
2. Locate the memory module cover on the bottom.
3. Remove the screws from the cover and take it off.
4. Find the alignment slot on the memory module and align it with the receptacle. Push it gently to make sure it is secure.

These are general directions, but your laptop might be slightly different. Your manufacturer will probably have directions for this on their website, so if you have questions, you should go there. For some manufacturers, opening the bottom of the laptop may cause the machine to go out of warranty, so be aware of this before you remove the screws.

There are a few other causes that you might investigate if none of this works for you. Check to see if your power button is broken or has a short, if your laptop is overheating or a fan isn’t working. If one of the fans isn’t working at all, many laptops prevent overheating by not allowing the machine to power up. Most of these are things that a trained technician should explore.

In any case, if it is a power supply issue, your data is easy to retrieve. All you have to do is remove your hard drive, put it in a 2.5″ enclosure (you can buy these online or at your local computer store for around $20) and transfer your data to another machine. After that, it is up to you whether you want to spend the money to fix this particular laptop.