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There's a button named "Stand By" this is probably the cause of your mixer issue, just take the button cover up and insert the spray cleaner pipe inside and give it 2 or 3 shots, then push it in-n-out several times and re-check the mixer outputs, let me know a bit more to improve help.
have you tried using a foot pedal? Are you sure it is switching (green light turns red, etc?). On the lead channel are you turning up the gain all the way and the volume down?
You can apply an audio signal to the input and with a small amplifier with speaker you can trace through the circuit to locate which IC failed.
The input to the small amp split iattach 2 wires pr test least leads from a meter, ground the ground lead of the little amp to the mixer chassis, and then with the other wire/test lead trace the defective channel 1 IC at a time until you lose signal.
If you download the IC's data sheet, Most likely a 4558 typse, you can speed the testing by simly testing at the amplifier inputs and output of each section of the IC. When you lose the signal, you found the offending IC- use the other channel for compairison.
Digikey has a site search, so you can enter the number on the IC to find if they carry it, or a similar IC, and who makes it- on the item specification page there is a link to the datasheet. While they may not have all of them, they have quite a few. http://www.digikey.com
It could be a couple issues in that section. Start by cleaning the contacts and switches to make sure it is not dirt. Also check to make sure the plug you are using is right for the jack- just to make sure everything is connecting as it should and nothing is inadvertantly getting shorted- such a 2 pole plug plugged into a 3 pole jack.
If those are all okay, the issue is in that boost channel section. Check to see if you are getting both power rails at the IC's, measure on a 4558 chip pin 4 to chassis should be -15 volts and pin 8 should be +15 volts to chassis. if you do not have this voltage, check the wiring, check the PC board for bad solder joints and check capacitors. Also check the physically larger resistors.
If you have the voltages, put an audio source on the input and set up a headphone with test leads, or better- an impedance matching transformer with test leads on the high impedance winding- put one to ground, with the other lead, move from IC to IC to locate the area to look at. You can get a data sheet for the 4558 here: http://www.ti.com/lit/ds/symlink/rc4558.pdf It is a low noise version of the 1458 family of op-amps. Check each IC at the inputs and the output, once you locate the stage where inputs are clear and output is garbled, that IC may be the fault, or something in the vicinity- usually it will be the IC. You can get any configuration of the 4558 you need through Mouser or Digikey, and Digikey does ship worldwide http://www.digikey.com
Once you get the new IC in, you should be groovin in no time.
All amplifiers make a little bit of noise (hiss) but it is normally slight and drowned out by playing. However, assuming that this is not normal system hiss, here are a few simple steps to try and locate the source of the problem by process of elimination.
SAFETY FIRST - a common cause of a humming or buzzing sound can be a lack of earth (grounding) on the mains supply. With a 240volt AC supply this hum will be at 50hz (in the UK) - frequency may vary in other countries but should be similar. Check the earth first because of risk of electric shock. Until you are satisfied that this is not the cause of the problem DO NOT touch any metal parts of the amp. Remove the mains lead and try a different one. Try plugging the amp into a different mains outlet socket (preferably one on a completely different circuit).
Turn off other electrical equipment in the vicinity that may be causing interference. Move the amp a bit, try rotating it by 90 degrees to change relationship to things like mains electric cables in the floor.
If you are using the line-out socket to give a feed to a mixer, slave amp or p.a. system unplug this. Sometimes double earthing (through the mains lead of your amp AND the mains lead of the MIXER / PA) will cause an 'earth loop' due to a different resistance at each end. Putting a DI box with an 'earth lift' in between may eliminate this problem. Alternatively there are little gadgets you can buy to do this (I found one intended for car audio systems on Amazon that works very well)
Unplug any instrument leads - to eliminate possibilities of interference affecting cables, effects pedals or guitar pick-ups. Also unplug the foot-switch.
If that stops it plug a lead in without a guitar on the other end - does the noise return? If yes change the lead. If no plug the guitar in.
Try moving the guitar in relation to the amp (turn it around 90 or 180 degrees) - this will be pick-up to amp power supply interference.
Does the sound get better or worse if you touch metal parts of the guitar with your hand? This may be a screening issue within the lead or the guitar itself.
Try turning all the individual channel tone and gain controls to zero, turn off any effects on the amp panel. If that eliminates it only turn up the controls on channels that you are actually using.
The intergrated circuit is most likely gone out. Not much you can do, cost in repair is more than the amp. Check out the peavey vypyr, it's a great modeling amp for about $100.
Quick and dirty way is to turn up one of the AUX channels, say #1 on the Guitar player's inoput channel/strip. Have all other AUX #1 completely CCW so none of the others get mixed on the AUX.
Use a TRS cable from AUX1 output to the guitar players monitor amp.
NOTE. The signal to his amp will only be controlled by the AUX1 on his channel AND the AUX1 Master.
One normally uses the AUX outputs for monitor functions.
There is a problem in the PMP5000 that is LIKELY in the PMP3000 as well.
The problem is arcing in the rear-most power amp near the heatsink.
When this gets bad, it will short out and fry the power supply and the amp if it persists. The arcing will trip the overcurrent sense and shut down the unit including the display until it finally goes completely.
I have repaired two of the 5000's now with identical problem. There is inadequate insulation in a multi-layer board in the rear-most power amp. The arcing occurs between the output lead of the switchers and the source lead circuit trace for the 9640 switcher transistors. The output switcher lead unfortunately is an internal circuit trace and hard to fix. Once burned, the board becomes carbonized and conductive.
NEVER run the unit without a speaker load on the unit.
Exact same problem here. Any solutions? :/
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