When i turn it on it goes straight to protect mode. i checked all the out put transistors then i took a look at the power supply and notices a huge clump of solder making multiple points touch if i desolder then will it fix my problem
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First is to check to make sure the power supply is putting out enough power.
From your description, it sounds like the classic signal "clipping" situation.
Since I tend to work from experience repairing a wide range of things, and I am not finding any references to your amp, not even in Russian sources, not even a picture, I have to make some assumptions for the moment, but this will help locate the problem.
Solder some test leads to an impedance matching transformer and the other winding to a plug that will fit your good headphones.
With chassis underside exposed, power up the amp, and apply a song you know well to the input. Use the test leads to check the 4558 IC's that are most likely to be found in the preamp stage(s) of the amp. and follow down the audio chain until you reach the power hybrids. If you happen to have the discrete transistors, those are better to work with and much easier to test.
If I am testing an amp in this way, I am listening for a dead spot, or a spot where the signal is very distorted. Being careful not to touch the power buss. Simply putting a test clip on one lead and attaching it to chassis ground is the easiest and fastest way to run through an amp.
if I am checking discrete transistors, I am just checking at the base lead of each one, or the gate if it is a FET until I find a distorted stage.
If you have power hybrid IC's, check at the website of the manufacturer of the IC for data sheets on that chip. Use those as a guide for checking voltages for the hybrid, as well as to help potential shorted components such as a capacitor or a resistor that may have failed.
If I know more details of the chips the amp uses, discrete transistors, or even if it happens to be a tube amp I can be much more specific. Other things to check that are not always apparent- make sure there is a +15 colt supply and a -15 volt supply with respect to chassis ground when dealing with 4558 amp chips.
The protect light generally comes on when the is a short in the speaker cabling. as a test, turn on the mixer without any speakers hooked up. If it still goes into protect mode the problem is in the mixer. Take it to your local music store and have their tech look at it. if it doesn't go into protect, check the speaker cables by plugging them in one at a time. The bad one will send it into protect.
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.
Sounds like the amp is going into a protective mode. Make sure your outputs aren't shorted. If you're into electronics, look for bulging electrolytic capacitors or blown transistors. Something is tripping the safety in the unit!
It seems there's another component (a capacitor, a diode, etc) causing a short circuit to triac and transistor, or there's an over voltage on this stage, please check if the voltage is according to the one feeding the good channel.
Oh, oh... got one on the bench now... There is a design defect that causes a short and destruction in the power amp portion.
Do a test: Plug headphones into the main 1/4 inch jacks. The sound won;t be very loud since these are line outputs, not for headphones.
IF you get sound out those, then one or both power amps are dead.
Worst case: if one amp is dead, several parts including three power MOSFET transistors are fried for any of the dead channels.
The failure of the amp can wipe out the main power supply. If you effect windows light up, then the small power supply is operating.
If the big supply is fried, there are two large MOSFET switching transistors that are gone. Often several smaller transistors and dides and resistors and one switching IC goes. MOST of these are surface mounted parts and would be beyond the scope of what you can repair.
I am trying to contact Behringer about the flaw but haven't heard back yet.
The nature of the flaw is this: The is insufficient clearance on an internal circuit layer from the edge that fits into a slot in the power amp heatsink. Any humidity that enters can cause the insulation to breakdown and arc to the heatsink causing a chain reaction.
I repaired one of these already before finding the cause, but this one had a smoking gun! I just yesterday milled out the slot deeper and wider and will put insulating tape to prevent further arcing. The arcing that had occured burned away the internal layer and the connections. I will replace thoose with hardwire.
Repair of this problem is time consuming to weed out all the blown parts and to safely bring the unit back to life.
The current unit I am working on took out ONLY the power amp. A 30 milliohm resistor went up in smoke making a real mess. All three power MOSFETS are gonzo and a zener as well... don't know what else I will find. The previous unit was worse as the power supply was wiped as well.
I have one that has done the same. It is the next smaller size. The power supply fried a toroidal inductor in mine. Frankly, these things are a major pain to work on. You have to usually remove the front panel before you can remove the back power supply and power amp section.
If you have warranty coverage USE IT !!!
The protect feature in mine monitors the power supply load and shuts down the supply if it senses overload. They are hard to work on as you have to bypass the protect to troubleshoot and get to the root cause.
Use the old light bulb in series trick to limit the current.
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.