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Author Topic: Behringer XENYX X1832USB Repair-Schematic Wanted  (Read 419 times)

paelgin

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Behringer XENYX X1832USB Repair-Schematic Wanted
« on: April 10, 2020, 11:38:06 PM »
Howdy all.  I need a schematic for the USB version of the Xenyx X1832 mixer.

I bought a broken Behringer Xenyx X1832USB mixer on Ebay and am cleaning and repairing it.  I have the schematic for the non-USB version, which I was hoping would be close enough.  That schematic is attached.

Alas, it is not sufficient and I need a schematic for the USB model.  In addition to gummed up pots and blown resistors (on the power for the Op Amps for the headphone for some reason), I discovered that the USB is sending left and right, but sadly both from the left channel.

The non-USB schematic that I have looks close enough (so far) to be usable in my repair of the headphone circuit. 

In my testing, I found that the headphone circuit was bad, but everything else worked, at least after spraying some of the pots and switches with Deoxit Fader lube.  [side note: I had heard about the loss of intentional weighted "drag" in the slide pots and that is true].

Once I get it off my phone, I will post a picture of the circuit board after removing two surface mount resistors (47 ohm). They were in line with the plus/minus rails going to the two preamps outputing to the headphone jack.  Something pulled a lot of current through them and I suspect that the two Op Amps (4580) are also toast (three on order now, along with several resistors and parts to make a "5th Gear Overdrive" pedal).

Phil in gorgeous Young Harris, Georgia

ps, the schematic of a different model of Behringer USB mixer might also work for my purposes.  I just need to see how the USB is driven.
« Last Edit: April 11, 2020, 11:04:58 AM by paelgin »

paelgin

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Re: Behringer XENYX X1832USB Repair-Schematic Wanted
« Reply #1 on: April 10, 2020, 11:50:02 PM »
Howdy all (both of you who read these threads). Here is the picture showing the area of circuit board where I removed the two surface mounted resistors.  One had burnt the board before failing, and I don't know if I will need to wire a jumper or how I will attach a new resistor yet.

Once I get the parts (should be Tuesday), I will see what I can do.

Any comments or suggestions are welcome.

Phil in gorgeous Young Harris, Georgia, USA

joecool85

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Re: Behringer XENYX X1832USB Repair-Schematic Wanted
« Reply #2 on: April 15, 2020, 10:14:46 AM »
Hav you contacted Behringer to ask for a schematic?  Historically I've heard that they aren't terribly willing to share, but these are unprecedented times.  I would try.
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paelgin

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Re: Behringer XENYX X1832USB Repair-Schematic Wanted
« Reply #3 on: April 15, 2020, 03:03:00 PM »
Howdy Joe.  Thanks for the thought.  Originally, I had looked for any link that would get me to Behringer support and they all led to "the tribe".  This morning (April 15, 2020) I tried again but cannot connect to anything Behringer: all websites are down and clicking on any links (from Goggle for example) leave the browser just spinning with no results.

Regarding my repair, I got parts and installed the two resistors.  On the burnt one with no pads left, I scraped the traces down to copper on both sides, tinned them then soldered in the resistor on one end.  Then I added a short jumper wire (single strand from a 20 gauge stranded wire) by soldering it to the trace and then onto the top of the resistor.  I'll attach a picture. The resistors are inline with the plus/minus 15 volt rails fed to the two dual OpAmp chips (one for left, one for right) feeding the headphone jack.  Not ideal, but may be sufficient.  If I could not get that to work, I was going to run an axial 1/4 watt 47 ohm resistor between pin 8 and another chip pin 8.

When I reinstalled the power supply and turned it on, I carefully watched my Watts Up inline power meter. When the power went to 79 watts (compared to 24 watts before), I quickly turned it off, but not before a wisp of smoke came up from the solder flux left behind.  I decided to replace the two chips those resistors were "protecting". 

With the two inline 8-pin through-hole OpAmps replaced, I tested and found input power used was 24 watts again. While the headphones do work, the volume in the left channel is much lower than the right.  I found two more resistors out of spec inline with the left side output (supposed to be 47ohm, but are over 1k each.  The right side was not affected.  I wonder what happened to smoke the OpAmp (left side, but maybe both).

As before, the USB is two channels sent to the PC (Main Mix supposedly), but right now, both are incorrectly controlled by just the left channel.  I looked at the USB board but without a schematic and with no obvious trauma on the board, I did not know what else to look for.

Thanks again for the suggestion to try Behringer; I will try again.

Phil in gorgeous Young Harris, Georgia, USA

ps, I am not in love with this mixer.  The Design might be fine, but the components used (pots and switches, for example) are not impressive.  And the inputs are on the noisy side (to check for pot crackling on the channel strips, I just turned up the gain and heard the white noise while I spun the pots up and down and listened for crackling as an indication to apply DeOxit Fader Lube).

paelgin

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Re: Behringer XENYX X1832USB Repair-Schematic Wanted
« Reply #4 on: April 24, 2020, 12:31:04 PM »
As suggested, I reached out to Behringer (The Tribe?) and received a reply:
"Dear Phil,
Thank you for your patience. We do not provide schematics.
We can offer a non-warranty repair for you, If you'd like to continue with service, we can start a claim for Non-Warranty repair. The charges are as follows:..."

So I replied and said that I had been told that but in these times I should try anyway.  I also said that I would not pay to repair it since I can do it myself but I need just the USB portion of the schematic.  Waiting for another reply.

I had sworn that I would never, ever buy a Behringer anything but I got carried away with this broken one at a good price.  My personal feeling of Behringer is that it is the Walmart of shopping, the Yugo of cars, the ... nevermind. 

Right to repair is a big issue in some cases, and Apple (and others including John Deere) are involved in lawsuits regarding some of this.  I just appreciate when a manufacturer cooperates with the end user, specifically on stuff out of warranty.  Fender and Peavey have been great to work with, while Mackie, Line 6 and now Behringer have stuck solid walls around their proprietary information (and not without cause but there should be limitations and exceptions).

Phil in gorgeous Young Harris, Georgia, USA

joecool85

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Re: Behringer XENYX X1832USB Repair-Schematic Wanted
« Reply #5 on: April 24, 2020, 12:35:02 PM »
Hopefully they have a change of heart given the current situations going on.  Good luck!
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Axldeziak

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Re: Behringer XENYX X1832USB Repair-Schematic Wanted
« Reply #6 on: April 24, 2020, 03:38:04 PM »
I have seen mention that Behringer uses the Cool Audio V2902 for it's USB codec. It's a clone of the Burr-Brown TI PCM2902. Try looking at Figure 39. Bus-Powered Configuration on the PCM2902 data sheet for some clues.