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Mixer Switch on and after a short period theres a noise that sound like a machinegun and a Hiss sound through the speakers


I assume that the power-amp is good.
This noise, of course due to defective parts inside.
But, which section is it? Chances are:
  • Amplifier circuit in the Main-Outputs. If the MAIN MIX in the minimum position and still noisy, then the damage in that section.
  • At one or several channels. Let's test.
    Set to minimum volume for all channels and MAIN MIX. EQ=flat. FX=minimum. TRIM at half (let's try at 12 o'clock).
    Raise the MAIN MIX, let's say at 15.
    Gently, raise channel 1 volume to maximum, listen, if there is no noise, channel 1 is safe. Lower the volume to the minimum again. Move to another channel in the same way.
    If found noise, that is where the problem is.
Actually, many more detailed steps for testing, but the description is too long. This above is a simple way.
Circuit power supply should also be checked, whether all normal voltage.

mixer-switch-after-short-period-theres-imlh0v44wkwtg1kaqtxpxnrr-2-0.jpg

mixer-switch-after-short-period-theres-imlh0v44wkwtg1kaqtxpxnrr-2-1.jpg

It is part of the image of the amplifier section circuit.
Parts which may be broken is the IC 64,65,77.

Sep 13, 2015 | Behringer XENYX 2442FX Mixer

3 Answers

What would cause a buzz in speakers?


There are many causes of buzz, so it should be checked step by step :
- Bad connection on the input connector, or cord.
- Amplifier, basically have the block diagram like this. View image.25850665-l1qpqmriditabltrjczr2eku-2-0.jpg
If in one block damage, buzz can be heard.In the amplifier.
Generally occurs in the PSU and / or power amplifiers.
Fix it to the experts,because it requires a good knowledge of electronics.
Blown speaker cone, does not cause a buzz.
Short circuit along the wires supplying the audio, it will not cause any sound in the speakers, including the sound of music.
Try also, disconnect the input connector, whether the buzz is still audible. If after the input connector is removed, the buzz disappears, the possibility of buzz came from another device before the amplifier.

Sep 05, 2015 | Behringer Xenyx 1202 12-input 2-bus Mixer...

1 Answer

Model Yamaha ME-50 no power


John
With AC power off.
Use a meter (on Ohms scale) to check internal fuse for blown (open) fuse.
If you feel qualified & safe with AC Power On.
Check input to internal power supply on AC Scale (Caution when AC is on) for volts in.
Use meter on internal Power Supply for "probably" DC volts leaving internal Power Supply electronics to power the rest of the electronic circuits.
Switch mode power supplies can break down. They stop doing their high frequency switching so they don't convert AC to DC.
If this P/Sup is a separate box or circuit board, inside the unit, then it can have a part number & be replaced.
Good Luck

Jul 14, 2014 | Yamaha Music

1 Answer

My Behringer XENYX 2442FX Mixer does not power up, the only light that comes on is the phantom power light. I opened it up and noticed that the switching power supply has multiple voltage outputs.


You should find +/-15 volts and probably +12 volts an +5 volts as well as the +48 phantom supply. If only one of these is missing, check the regulator for it... most are three terminal regulators. If the one that is missing has a hot regulator you have a short someplace and this requires skill to locate Probably the fastest way is to use a thermal imaging camera... however I have often used a millivoltmeter to find where the supply drops tpo near zero. Using a "calibrated" finger and search for a hot component on the circuit board can be very effective. Likely one of the surface mounted chips has shorted. Replacing these requires skill so best leave board repair to a skilled repair person as you can easily damage the board permanently.

Oct 04, 2011 | Behringer XENYX 2442FX Mixer

2 Answers

I need power supply sharp b099 v555750 do you


You can order it @ store.musicservice.pl... just e-mail them
BR

Jul 03, 2011 | Yamaha Music

1 Answer

Device powers on and goes through startup but no light. lamp is new. scanner moves but no light


Yep... I got one on the bench and also another I have just fixed. The one that is still sick has a lamp power supply that is inoperative. There are two supplies in this unit. One powers the electronics and the motors, the other the lamp. The lamp one is mounted bottom side under the lamp. I have partially traced out the circuit and I am trying to analyze it. It appears to have two transistors that drive the step down transformer that generates the 24 volts for the lamp. It appears they MAY use a Diac as a relaxation oscillator driving the bases of the large switching transistors. The circuit is fairly simple and has a small transformer for driving the bases as well as the larger output transformer. This supply operates directly off the line input so one needs to use an isolation transformer for personal safety when troubleshooting. I suspect the Diac might be gone in mine. The one I just fixed had been dropped and the plastic standoffs for BOTH power supplies were broken. The smaller supply on the one I repaired had the power transistors fracturing the circuit traces they were attached to so supply would not operate. Jumpering the breaks fixed the problem. Also on that one the audio sensitivity pot was smashed. Replaced that. I will be working on the one with the bad 24 volt lamp power supply again. In the meantime, see if on yours the ONLY problem MIGHT be the big power transistor leads have broken loose from the circuit board
The supply is mounted on three standoff plastic pins to the cover with the grill punching on the back side. Remove BOTH long side aluminum extrusions (8 screws +1 more) to free the long plate with the supply on it. Chauvet STUPIDLY have the heatsink aluminum dangling by the two power transistors so bumps flex the transistors... you will see it when you open it... You can contact me as fredy2 at the AOL.com.

Apr 27, 2011 | Chauvet Dmx-600 Intimidator 1.0 Color...

1 Answer

Behringer XENYX 2442FX Mixer. The power light does not come on, The +48V does come on. The solo light blinks Constancy. No sound. I checked the fuses, they seem to be OK. any ideas on what wrong


You have likely lost one, probably the +15 volt power supply... This is possibly a shorted component or a short on the circuit board causing this. It takes some skills at troubleshooting to find this. Sometimes using a thermal imaging camera will show hot spot... other times you have to search with a millivoltmeter. The rude solo light is driven by an op amp that uses both polarities of 15 volts and to turn it on it pulls negative... Hence I suspect the +15 is missing.

Nov 05, 2010 | Behringer XENYX 2442FX Mixer

1 Answer

My casio ctk-710 does not work with the power supply, only batteries and i already try several powers supplys


There is a contact switch in the power connector that must be making for batteries to work... I suspect that either the soldering of the power connector or possibly a broken circuit trace to the power inout connector may be the problem.

Oct 23, 2010 | Casio CTK810 61 Key Keyboard

1 Answer

My DigiTech RP90 expression pedal isn't working at all


If you are getting no display after you try powering up properly check the plug end of the power supply with the supply plugged in with a volt/ohm meter. You should get a reading of 9volts. If you don't ,your power supply is not working. Sometimes the wire breaks where it goes into the supply and sometimes where it goes into the plug. Your power supply jack may be broken where it is soldered to the circuit board. If the unit has power you can do a factory reset. The procedure is on page 34 and 35 of the owners manual that you can download for free here:ftp://ftp.digitech.com/pub/PDFs/Manuals/RP90/RP90Manual18_0490_A.pdf Let me know if this helps.

Nov 26, 2009 | Music

4 Answers

The 'protect light' comes on Fender PD150 Portable Sound System


The protect circuit is activated by a current sensing transformer in the *input* of the power supply. If any of the subassemblies of the unit (or all of them in combination) draw excess current then the protect light will illuminate and the power supply shut down to prevent any damage to the system.

The circuitry in the power supply is fairly robust as well as fuse protected so it is unlikely that the power supply itself has failed. More than likely one of your output power transistors has been shorted and it is easy to check this yourself if you are interested in doing so.

Furthermore if you follow a few *simple* precautions you can do this safely and confidently.

Post again on this thread if you are interested and I will spew the details.

-BK

Nov 28, 2008 | Fender Passport Deluxe 500watt Sound...

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