I love the UHF-5800, but I have a hum coming from it now. I had the original power supply short out and replaced it with a different power supply. It orignally takes a 13v 800ma supply but I could only find a 12v 500ma power supply. It seemed to work the first few times, but now I've developed a hum. It happens only when the wireless receiver is turned on. I'm wondering if the short from the orignal power supply caused more problems with the reciever or if the new power supply is not good enough. I have a hum reducer that I uase for my laptop, but it doens't worrk when plugged into the wirless unit. Any ideas are greatly appreciated. Thank you!

Dead battery?

Is the hum there with NO input cables connected? If not, you have bad cabling. Make sure you use only XLR to XLR mic cables and not the junky ones with a 1/4 inch plug that are for Karaoke machines. These devices usually use switching power supplies and do not have the power supply originating hum of older equipment. If the volume control adjusts the hum, then the hum originates previous to the control which is either in the preamps or the external inputs.

One of the power supply voltages is bad... either a short or the regulator is blown. Follow my instructions for a previous poster:

http://www.fixya.com/support/t10013559-mackie_1604_vlz

1. Check microphone(s) batteries and replace if the
charge is low.
2 Remove local sources of UHF interference, such as
lighting equipment.
3. Adjust the squelch controls on the front of the UHF-
5800 receiver.
4. Signal may be too weak. If so, reposition antennas.
If possible, move them closer to the transmitter.
5. Reposition the receiver, perform a "walkthrough",
and observe the signal strengths. If audio dropouts
persist, mark these "dead spots" in the operating
area and avoid them during the performance.
If none of these could help it is possible that the device has really some faulty operation and needed to carry it to service center.
Good luck!
gylacz

hp does not sell parts that old sorry, why assume the most expensive part is bad first?????????? rich?
only sold on fleabay, (or off scalpers sites endless)

the list in order, posted here 1000 of times.

1:big battery out. leave it out until it runs again ,ok/? batteries this old LOVE TO SHORT !!!
2: new coin cell RTC for $2 , covered in the manual.
3: got text now.? BIOS keys work now?
4: power pack dead? 19vdc is good, way less not.
5: does CD try eject? fan dead? you never said either. and is key to all diagnosis.
6: does the screen pass the flash light test?
pointed at screen? CCFL ddeathh?
7:no beeps no caps lock flash codes?
HDD not heard to spin (ear to side sure)
8:run with 1 ddr memory stick (1 AT A TIME NOT BOTH?)
9: this PC loves to fail, CCFL-back lamps tubes and this old RTC COIN CELLS ARE BAD. WE CAN GO FARTHER.
AND MOBO IS DEAD LAST, ALWAYS, !!! NEVER 1ST,

learn that up to 20 things can short there.
inside,
and make 10000 good motherboards all fail.
and all be good.
see?
shorts happen, in all electronic devices, and systems. we remove them all to find who is shorted.
the regulators on board shut down to save the system
that is how it works. shorted./

If it is accros both channels (on every imput) your best bet is to replace the large electrolytic capacitors in the power supply, these filter out the 50/60 Hz hum from the mains, so they might have failed. Electrolytic capacitors anywhere are good at causing hum!
If they are say 4700UF at 50Volts, you can replace them with any UF rating higher than that, and the same with the voltage. Never go lower than the ratings marked. Also keep an eye out for the temperature rating. It will be given marked "c". If it says 105C then replace with one the same, though it will work with a lower rating it will fail faster than normal. The only problem with electrolytic capacitors is 'space' to fit as they come in many different sizes. So bare that in mind when you a tracking down replacements.

This failure might not be in the power cord but the internal power supply. If your LCD is older then 15-18 months for sure it needs a power supply replacement.
Symptons of a failing power supply are:
1- Set does not powers ON.
2- Turns OFF by itself.
3- Needs to be unplug to make it powers ON again.
4- When the set is ON, it produces a humming noise through the speakers.

You can find a power supply replacement visiting this website and you should be able to replace it yourself.

first of all check the antenna connection, it could be dirty which causes more impedance at the higher frequencies than at the lower ones (uhf is higher than vhf), also hum could come from a power supply that can't produce enough current, does it get worse when you turn the volume up high? if so and you use a wall adapter, you might need one that has the same polarity and voltage but a higher current output, such as 400ma compared to 250 ma. If the power comes from a standard ac cord without the transformer (cube) at the wall outlet, then the internal supply might need a new capacitor in the filter circuit.

it is due to 60Hz HUM IN POWER SUPPLY. please check for input supply. also check for mains filter capacitor in tv. also check for one diode open in rectifier ckt.

Have you tried using a different power adaptor? I have noticed with mine that the as the original failed there was a noticeable hum, a new power supply (of reasonable quality) solved the problem.