Missing manual I want to get a manual for my QSC PLX 3402 amp. I can't find anyone who would have one. Any ideas?

The Service Manual is here

https://www.manualslib.com/manual/1076895/Qsc-Rmx-Series.html#manual

The company is here

RMX Series Specifications - QSC

https://www.qsc.com > q_amp_rmx_series_specs
PDF
RMX2450. RMX4050HD. RMX5050. Stereo Mode (both channels driven). Continuous average output power per channel. 8? / FTC 20 Hz - 20 kHz / 0.1% THD.

Hi,

Please specify a bit more, does the rattle is physical(Enclosure structure) or electronically hear thru speaker(Power Amp Common Issue)? I have the solution for the amp issue, let me know.

Most likely...shorted speaker wires, defective speakers or too many cabinets wired together can blow a amplifier channel in an instant. Manufacturers use to mount protection fuses on the exterior of equipment but people started replacing 3 amp with 25 amp automobile fuses and destroying internal circuits. You could pop the cover to look for a power supply protection fuse (same value replacement please) BUT be careful as there are sustained voltages after the unit is disconnected from the AC outlet that hold enough power to make this type work dangerous. I recommend sending it to a professional repair shop for a checkout and estimate.

Hay una placa base Soltek (EQ3402A) (EQ-3402 a) There is a motherboard Soltek (EQ3402A) (eq-3402 a) that is out there. You would need to give more information about what your machine is, which would help identify your control board.

Good Luck
Markos

Disconnect speakers. With NO input, if clip light remains on, take in for repair as there is an internal failure. If reducing the gain and loudness keeps the clip off, then you are probably driving the amp too hard. This is common problem when the user "thinks" they need it louder but the amp speaker combination will not deliver louder. At this point, both the amp and the speakers are at risk of permanent damage requiring repair.

You should NOT drive the amplifier into the clipping mode continuously. There is a possibility that you have fried your speakers or that they are the real problem. You haven't told us what you were driving, however this amp will deliver 450 Watts per side RMS at 8 ohms which means your speakers have to be rated at least that much RMS power for continuous. When speaker voice coils fry, they can wipe out amplifiers. Let us know what speakers you are using and how they are configured. This amp is going to be expensive to repair I can tell by looking at the schematic: Here is the schematic:

http://elektrotanya.com/qsc_plx2502.pdf/download.html

Scroll down to "get manual" and click to download it. IGNORE other download links.

This amp has circuits to boost the power supplies to the amps to handle the peaks. It is rather complex but the schematics are complete and have good explanations... some of the best I have seen. There are going to be a lot of destroyed components and great care has to be used after repair to "cold start" the unit to make sure nothing else is bad or it will blow up again. Most people do NOT have trouble with the QSC amps... so do tell me what speakers you are using and how they are configured so we can verify the design is correct. This amp is rated for 8 ohms so USUALLY only ONE speaker can be connected per side... and finding an 8 ohm speaker that can take 450 watts continuous RMS isn't easy. People fall for the advertising claiming "Peak" and "Program" power which are FAKE advertising... ONLY use continuous RMS power when sizing amps and speakers. There are MANY ways to cook out equipment... One is to boost the bass or the treble way up. Another is to NOT use balanced interconnect lines between mixers and your amps. Yet another is to NOT power ALL interconnected equipment from a single receptacle or power conditioning module. Please describe your setup further so I can help you more!

I need a board marking number as there may be several caps near the on/off switch.

Example:

C117 .47mfd 250VAC (use 600VDC)

C126 .1mfd 250VAC (use 600VDC)

C132,133,136,137,140,141, All 2200mfd 200VDC (These are large canned units)

Note if one of the latter ones, better check the full wave rectifier bridge for a bad diode as well.

I have the schematic but not an assembly drawing so description of near switch doesn't tell me enough.

Yes. Make sure you specify Nikon when you order/purchase the unit.

The amplifiers protection circuit when active will lower the volume significantly and sound poor. Is the amp driving an impedance it's happy with, not being overdriven and has adequate ventilation? Do the fans appear to work ok?

Take the speakers and all cables loose from it plug it in turn it on see F the protection mode stops F so 1 of your connections is bad