problem with behringer MX3282A.... please help!!

[SHORT EDDY]

The MX9000 used the Panasonic 100mm faders which are considered the best low cost pc mount faders and was one of the reasons Mackie claimed was justification for suing Behringer over the MX9000 being a "copy" of the 24x8 Mackie. The complaints claimed that Mackie had an exclusive right to the Panasonic fader which Mackie was basing some of their PR effort on. The judge in the case thought the claim was strange so not being an engineer, he started looking at parts catalogs to see what was the norm in the industry. Apparently the lawyers did not bother to check their own fact because the judge found the Panasonic fader was available to anyone, including Behringer, who ordered from Digi-key or any of a hundred different supply houses. There was also a claim that Mackie had a specially designed 60mm fader that Behringer was illegally using because of exclusive rights to, which turned out to be a standard line item in the Alps short form catalog. Behringer used Alps on almost all their mixers except the 100mm used in the Mx9000. They are both very reliable and closely trimmed faders but as mentioned, the 100mm Panasonics are very tight in tracking balance and position accuracy. So the 3282 used a cheaper less exacting fader but so was Mackie and most others making small form mixers. Some use the Alpha faders which are not as accurate as either the Alps or Panasonic in my experience so the active component quality for transistors, ICs and moving elements like linear faders were pretty much like everyone else's of the better small mixers except the MX9000 which used better than normal faders. I have found the Alps to be fine and only suffer when abused, like all linear faders and other than due to spills or physical damage, seldom needed replacement.
One of the reasons the Behringer pc boards get high marks for construction is their resistance to intermittent solder connections. Surface mount is mostly the aid there but the few components that do use thru-hole placement have little room to spare around the lead which is also an aid to keeping solder joints solid. That tighter fit is not stuck, just little room for slop, so if desoldered well, with appropriate heat localized to the joint is applied the part comes out easily without damage. That applied to highly heat sinking connections such as ground planes where solder flows on both sides of the board.
You can pre-heat the board, they will handle in excess of 250c with a pc hot air stand or wand or using very low temperature solder for low temperature removal. I prefer the latter method if there is any chance the part might be used again. The whole desoldering job of, say, a dual gang pot with support solder tabs, that is mounted with heavy ground planes top and bottom is capable of damaging any pc board is done with a big iron or solder gun. The Chip-Quik method only requires bringing the joint up to about 50C so when done, the part and board hardly feel hot to the touch, and the part just falls off without prying.
De-soldering stations and re-work stations used to cost over $1000 but there are Chinese systems that are well within the reach of any part time repair shop. It is a basic tool of the shop, no less important than a DVM or scope. A local parts house here was having a sale on a unit from Ya Xun brand that had a vacuum pump de-soldering gun head, a hot air head, soldering iron and an integrated heat stand for $400. Few need all that, however, a vaccum desoldering station can be had for $140 and hot air head and control box can be had for $80. It is not a repair shop unless it has the basic tools of the craft, even for tube-only shop that can't or won't work on contemporary electronics needs to be properly equipped or the customer is being slighted and risks having the value of their unit lowered by less than professional treatment of his gear.

I respect your knowledge.
I still own one of the first 500 Mackie 24X8's to be released. Never had to replace a fader yet. It does not have the same problem.
I operated on and repaired the model mentioned by the poster. I found the faders to have an inherent "defect" as I have previously described.
My intent was to point the poster to the most likely cause of failure based on my limited experience of replacing multiple faders on the same model and determining why they failed. I'm RIGHT about the faders failing prematurely, no matter how much you defend the company and point out design details.

[km6xz]

Except for the linearized rotary faders used in the 50s and 60s(string coupled rotary pots driving by linear sliders), is there any fader that works reliably when spilled into? The Mackie 24x8 is just as likely to have fader problems as a cheaper mixer if both are subjected to spills. It is not a design problem with the fader, it is a care and use problem of the owner. Yours is working because you take care of your mixer. What is the most common problem with the Mackie 1604....faders getting spilled into, at the same rate if failure as Behringer because they use the same faders, mounted the same way. If someone needs less easily abused club mixers they should look into rotary control mixers which are mounted vertically and behind a locked transparent door. That is very common in clubs with major investments in sound systems, the limiters, line eq, compressors, power amps and line mixer is tested, set and locked up so only the feed signal is controllable by the dj or house mixer. With 50,000 watts available in many of the clubs, just another dumb sound guy is just too much to tolerate having control over the considerable investment.

[Enzo]

My report is independent of Stan's. In my years as a Behringer service center, I have to say I encountered no higher level of fader failure than in any other brand either. I see the same things everywhere. If you spill crap into them they will fail, yes. How would they not? I see people smack/drop something on/otherwise push down on the fader lever, and pop the bottom out of a fader. Usually we can fix such sprung faders. I find it more likely the resistive stripe opens than debris bunching up in the ends.


A house mixer? As in anyone can use it, and it belongs to none of the users, who then do not exercise the care a real owner might?

[ahthatsme]

I have a simular problem with all lights lit but also pin 2 on the connector is burnt. The connector on the circuit board in the power supply was also burnt.I replaced the circuit board (in the power supply) but still having the same problem. Any sugestions?

[km6xz]

The power pc board locking header connectors can burn if they oxidize or become corroded, which generate heat, which accelerates further heat and burning. If there is any discoloration of the plastic plug end, replace all the pin on the pc board and the cable end plug with the crimp wire ends. Cleaning or deoxidizing will not fix it. Some people get lazy(or smart) and replace the Molex connectors with wiring directly to the pc board..
If all the lights are on, one of the bipolar power supply rails is down. That can be due to a fault in the power supply, the connector described above or quite often due to a short somewhere on that the rail that is down. It most likely is a shorted bypass capacitor or a shorted IC. With so many stages of the circuit drawing power from the same rails, it could be any of them. Try unplugging section connectors to find what general are the short is if possible.
What test gear do you have and are you familiar with circuit tracing and use of test equipment? Test the power supply first, a voltage regulator might be at fault so one rail reaches the mixer. If the supply is good without a load, it still might be unable to supply enough current to the mixer. You could break the connection on one rail to the mixer section and insert your ammeter to see what current is being drawn on one rail and repeat for the other polarity rail. They should be similar in current draw.