Has Anyone Ever Recapped a Behringer Mixer Board?

I would think it highly unlikely that you have tow phono channelw with electrolytic caps that are failing at the same time, creating the same effect.  In fact I would find it highly unlikely that you have failing caps in something this "modern"  Caps made in the last few decades are not like those of vintage radios, or even 30 years ago.

I have several Behringer mixers in my world.  One in my office at work, several throughout the studios at work, and a couple at home.  Generally caps don't go bad unless they are in constant use.  The little mixers at work have been powered on for over 10 years, and no issues yet.  They may not be high end units, but make great little "utility mixers" and out of probably 10 or so, I've never had an issue with one. 

Realistically, anything is possible, however unlikely.  Both TT channels went to heck at the same time?  If you have an external preamp laying around try one of the TT with that and go into the line input rather than the phono input and see how that sounds. 

Not being familiar with this particular mixer that's all I've got off the top of my head. But geeze, I can't remember the last time I had to replace caps in something made in the last 15-20 years. And then it's gotta be something that's "on" 24-7, unless maybe something took a hit with a power surge when being turned on, but again, pretty darn rare!

TIB

I have had power spike issues here several times while the station was in operation. Hard to say exactly what the cause was but when all your lights are dim and there's no 220 to operate an oven, by the way, the normal line current where I live is 118-120 volts, but electric stoves use 220 Volts. I assume if a transformer trips and there is a lack of sufficient current to supply every home on the service line, so the current runs below 118 volts with the neighborhood drawing whats left of the supply, so basically some of my equipment ran in that condition for up to an hour once or twice.

It's happened at least 4 times in the last year, so that's got me wondering if one of the mains in the mixer is having issues and I notice it more when using the turntables.

Everything works on the mixer as far as all the LEDs goes.

Bruce.

I have also found they don't play well in strong RF environments.

My hunch is that the inputs are not providing the important RIAA curve to give the vinyl records their proper equalization.

I agree with Tim's suggestion of comparing it by using an external phono preamp.

Phono cartridges will sound very tinny if fed into mic inputs, if that's what's happening.

If you feed a stereo signal into

some kind of amp, and you lose

the ground connection to both

channels, the two slightly different

L and R sources will still try to 

be amplified.  What you might get is

an out-of-phase hollow audio signal

that is the sum and difference of the

2 channels. 

Or if you get one channel out of phase

somehow (maybe if you lose the ground

to any one channel) you might get something

like that.  

I don't know how to explain it really, I'm not

an engineer, so I can only tell you the little

that I know.

I had a piece of equipment with a MONO

switch.  This combined the stereo channels,

but I think something internally in the unit

was wired backwards.  One stereo channel

was out of phase and I got a condition not

too unlike what you describe.  

I don't know.

It's something to think about anyway.

I wish I lived next door to you so I could

help you troubleshoot the thing.

Check ground connections(?)

I don't think it's a cap.

Broooce, WLP 

In reference to what Carl said.

The turntables are connected via RCA jacks to the proper phono inputs of the mixer and the turntable grounds are conected to the mixer ground screws.

I do notice, that although, both turntables have the same exact cartridges, one carttridge has a higher audio level, while the other appears to be lower, but a slight distortion. When I tap each cartridge head shell with the mixer's trim and level sliders turn up and listen through the mixer's headphone monitor circuit, depending on what turntable that carttridge is on, one carttridge picks up almost as if there is a microphone hidden inside the cartridge, the audio is loud and clear when I tap the cartridge.

However, with the other cartridge on either turntable, taping this cartridge results in a lower but sort of distorted sounding result. I am also noticing, with turntable number two, when I turn the mixer volume up to a certain point in level, there is a slight AC sinewave issue in this turntable only when it's power plug is plugged in. The other turntable does not exhibit this issue.

The ground is okay, I checked that with an ohm meter with the bottom cover off and the ground wire is attached to the same areas of both turntables.

There are electrolytic capacitors on the circuit boards, those do not have anything to do with the wires that run from the cartidge to the external RCA jacks. I believe they have to do with the pitch control and cue circuits. I notice the AC sinewave only when that turntable is plugged into the mains. I may have a bad capacitor in that circuit allowing the AC sinewave to get into the ground system.

Now, thinking about ground loops. That is also possible. I do notice a slight peak on the DSP1424p's left output meter. Just one bar at -40 dB. I have to trace that issue and remove it.

I know there is also a slight AC sinewave when the automated computer is on air. Thinking about running an extra ground wire from the computer's metal case to the mixer board.

The mixer is grounded to the DSP1424P and DSP9024 boxes through XLR connectors and 3 conductor Hot, Cold and Shield cables. Perhaps, I should run an extra ground from the mixer to the chassis ground of those two audio processors.

There is a ground wire which is indepenent of the AC mains ground. The AC supply mains ground rod is on an enterly different side of the house, realistically too far to run a decent ground to. So, I have a seperate ground wire on the shield side of things running outside my apartment to a ground rod buried in the ground.

If I take an ohm meter and set it to ohms reading and place one probe into the dirt and attach the other probe to the copper ground wire, I get an ohms reading. Of course, the dirt has to have some moisture in it for this reading to take place.

I get this reading regardless of whether or not there is anything attached at the other end of the ground wire, so this test tells me that basically there is a electrical flow taking place between the buried ground rod and the damp dirt anywhere within 3 to 4 feet of this location.

I am not sure if any of you have tried this before with the ohm meter and seeing if you get a response on the meter when placing one probe in the dirt and the other on a buried ground rod. But please share your results or tell me if you've noticed the same thing.

Now regarding those turntable cartridges, I know one cartridge is new, while the other is older. At the time I bought that new cartridge, it came with two stylus and one new cartridge, I should have bought two packages at the time, because the seller sold off the last package and no longer has any left. The stylus is Stanton DM-AL and associated cartridge. There are some cartridges on ebay, but in used condition, who knows how used they really are, I could be adding another issue to the problem.

Now, time for me to open up that second turntable and locate that AC sinewave problem and also locate that one bar -40dB peak showing up on the left channel of the DSP1424P.

I am not using the best computer for automated programming and the two sound cards, one for playback which is an older Trident 4D Wave and an older Sound Blaster 16 sound card for audio input (via LINE IN - Recording device) for streaming the audio on line. Plus I'm still running Windows XP SP 3 on that system. The computer is an old Dell Power Edge SC420 SERVER desktop computer system. It was actually designed to be used as a server and originally came with Windows 2000 server edition. So, I am not exactly using a media friendly computer system. I think it is time to upgrade to a media friendly motherboard, one that supports those high end audio cards.

Although the slots are there for high end PCI-E cards, I do not think the chipset is the greatest for media usage.

Bruce.

I can see that you are leaving no stone

unturned.

So I'm learning from what you are doing

and so are a bunch of other people.

You talked about measuring the resistance

in soil as referenced to ground, if I understand

correctly.

I have heard stories (I don't know if they are

true) where one person would feed an audio

signal into soil with electrodes and somebody

else would hear it some distance away with

an audio amplifier input connected to electrodes

in the soil.  I don't know about this...

Very best wishes,

Brooce, WLP