need behringer schematic ub1832fx enzo maybe you know?

[mattball826]

have a mixer with bad smps. not under warranty

unit was doa with couple blown traces on ac neutral line and ground. looks like some plugged into reversed line voltage (neutral side blown).

i changed out defective (shorted) rectifiers, bridge rectifier and rf line filter coil. also replaced the multipin smps driver ic, opto ic, 451 transistor. regulators on the sec side are all fine. components from mouser.

unit comes on now, but pulsates. leds, etc all flash when powerd on.

there are small sm resistors that might be open near the optical fb chip, but i dont know the values. they have flash burns from where the foil pads were damaged. there was one shorted hr303 diode on the secondary of the smps, i changed all four to be safe

i can do smps repair but i need relavant values to know these small smd resistors etc.

any help is appreciated! thank you much

email to: dbs4568 at gmail dot com if you can please

[Steve L]

I sent you the schematics. Too big to post here.

Steve

[mattball826]

thanks steve-

have that one, unfortunately it does not include the smps (modular psu) schematic.

[shlomi_shm]

Hi All,
I also have ub1832fx and unfortunately no signals come out from the main output. I opened the case and I looked inside. The PCB looks in good condition, no burned components. Power supplies to the op-amps are +/- 14.5v -- looks okay. The scope shows that the amplifier input signal are dead. I'd like to check the rest components but I don't have schematics. Could someone email the schematics to me? email: shlomi_shm at yahoo dot com.

Thanks,
Shlomi

[Enzo]

Make sure any insert jacks are not cutting your signal out.

And one very common cause of loss of output is failed main volume slider.

[shlomi_shm]

Make sure any insert jacks are not cutting your signal out.
And one very common cause of loss of output is failed main volume slider.

Hi enzo, thanks for replying so quickly.

Actually, a man, who perfectly knows this device has tried to help me to operate it with no success.
The led bar shows input signals. Also Control Room and Sub outputs work very well.
I've tried other inputs, mute and control buttons and I couldn't get any signal from the main output.
Do you have any other suggestion?

Thanks,
Shlomi

[Enzo]

Ah, no main channel inserts on this model.

OK then, if your CR and phones work, set them to monitor master, and then do the master faders control the level? I'd hope so.


Your main L/R outputs come from the L and R master faders VR115, VR116, through IC72, through IC68 and out the jacks. The tap for the control room/phones is between ICs 72 and 68. But that is just for monitoring the main. The CR/Phones can take signal from several points, so unless you have it set for mains, it doesn't help.

If CR works when set to main, AND the main L/R faders control it, then a loss of main out would look like IC68. But if CR works but only on other feeds, then we are back to the sliders or those two ICs. SImple signal tracing with test signal present should be able to spot where this breaks down.

SO I would start by looking at the main faders - is there signal on them or not. If so, then follow what I described. If not, then prior to them is IC38, a TL074, common to both channels.


And does turning off the graphic make a difference?

[shlomi_shm]

Hi Enzo,
Please see my comments.

Ah, no main channel inserts on this model.

OK then, if your CR and phones work, set them to monitor master, and then do the master faders control the level? I'd hope so.
The monitor fader controls the level. The main faders still don't work.

Your main L/R outputs come from the L and R master faders VR115, VR116, through IC72, through IC68 and out the jacks. The tap for the control room/phones is between ICs 72 and 68. But that is just for monitoring the main. The CR/Phones can take signal from several points, so unless you have it set for mains, it doesn't help.
The highest numbered IC that I found is IC63 (I have UB1832FX Pro model). I checked the traces (with fluke ) and I found that the L/R outputs are driven by IC63.

If CR works when set to main, AND the main L/R faders control it, then a loss of main out would look like IC68. But if CR works but only on other feeds, then we are back to the sliders or those two ICs. SImple signal tracing with test signal present should be able to spot where this breaks down.

I can't get any level control from the main faders, no matter what I do.

SO I would start by looking at the main faders - is there signal on them or not. If so, then follow what I described. If not, then prior to them is IC38, a TL074, common to both channels.
TL074 looks okay, I found signals in all 4 amplifiers. IC38 doesn't seems to be an amplifier (I think it belongs to the LED bar - the number that written on it is 339 - probably this is the comparator LM339)

And does turning off the graphic make a difference?

How do i turn the led bar off?





Thanks,
Shlomi

[Enzo]

I'll look and seeif the part numbers changed at different revisions or something, the drawing numbers were quite clear.

I can't get any level control from the main faders, no matter what I do.

BY that do you mean turning them up results in no output? WHat I am concerned with is the faders themselves, not the results they provide. USing a scope, a signal tracer or even an AC meter, with signal applied to a channel somewhere, is there signal getting to the pins of the slider? For example if I find a signal at the top pion of a slider, but nothing on the wiper throughout its traqvel, then I know I have a bad slider. SO the only test I proposed there is to go inside while it is running and scope or otherwise monitor the pins of the slider. What we want to do is determine if the problem is before or after the fader, if it is not the fader itself. SInce you seem to have separate L and R faders, I tend to think both did not fail together. But they are still teh starting point of my search.

And does turning off the graphic make a difference?
How do i turn the led bar off?

There should be a button lavelled something like EQ IN/OUT. That turns the graphic EQ on and off. My photo is not the clearest, but appears to be a button marked EQ IN just to the right of the graphic sliders. And just above the VU meter led strips. Pushing that button should then turn the EQ off. It is just a quick test, there are a couple ICs in that circuit that are common to both L and R.

[Enzo]

OK, I went back and looked. I was discussing the later revision F, but the older revision D does indeed have different part numbers, so I will adjust. Both revisions are UB1832FX-Pro.

The main faders are still VR115, 116. From them, L/R go through IC63, then IC59 to the output jacks. The tap out to the CR/Phones and the Tape Out is still between those two ICs. SO if you get tape out - and there is an on/off button for it be aware - then there is little left but IC59.

Actually maybe I am wording this incorrectly. The output is balanced. IC63 drives pin 2, then the signal from IC63 is fed through IC59 for pin 3.

The CR/Phones has a selectable feed, so for my test MAIN must be selected. I know ther is a separate control for volume of them, VR79, but what I mean is that once you have that set, and MAIN selected, then the main faders should affect the level you hear too. This because the fed to the CR amp is taken after the fader. Note too that I am not listening to the missing main outs at the moment. I am just listening to the CR to see if the main faders affect it, that helps localize the problem.


Before the main faders, in the EQ section, the signal path is through IC57, then 48, then 37. Each of those are shared by the two channels. SO this is why it is critical to know if the break is before or after the main faders.

[shlomi_shm]

Enzo,

I Think the problem is in the sliders - when I'm shorting the sliders' pins, I'm getting signals in the L/R jacks.
I swapped the main right slider with channel 6 slider and now R jack works I hear terrible ham noise - probably it is a different issue...

I'm wondering how could 2 main sliders (L&R) become broken at once...
Could you please tell me what the part number of VR115 and VR116 are? I'd like to order them in mouser/digikey.

Thanks,
Shlomi

[Enzo]

Oh, the two at once is pretty unusual, but it happens. Maybe they both took some trauma, some object dropped on that corner of the board. How many times have I seen sliders with their bottom pushed out due to impact to the shaft?

If they are bad, you are at the "what is there to lose" stage. Pull teh slider, carefully disassemble it, noting which way each part goes, and see if it can be repaired. Is the problem a broken resistive strip? Or is it that the sliding contact doesn;t make? Can't usually fix the stripe, but I have fixed slider shuttles many times. Maybe a wad of debris gets caught in the feeler, clean it out and reassemble.


The slider itself is a mono 60mm Alps part, 10kD. DEScribed as RS6011SA6D14

Behringer part number 800-33441-05353

[shlomi_shm]

Yes you are right, they have took some trauma - both have ripped brushes and one of them has broken lever. I don't think they're repairable.
Anyway, you helped me a lot. I'll oreder 2 sliders as you described.
I owe you big thanks for your patience and for your time.

Thanks a lot!
Shlomi

[Enzo]

If the resistor stripe part is OK, sometimes I find a similar fader in my drawer, take it apart and use the shuttle from that in my old fader.

[shlomi_shm]

Guys,

Do you know where I can find sliders for ub1832f?
Enzo Said:
"The slider itself is a mono 60mm Alps part, 10kD. DEScribed as RS6011SA6D14
Behringer part number 800-33441-05353"

I sent a quote request to ALPS but I got no response.
Does DigiKey sell these parts, if yes, what is the replacement number?

Thanks,
Shlomi