Behringer V-Verb PRO 2496 Not Passing Signal

Hey everyone,

First time posting here, so I just wanted to say hi! I've been a long time audio and gear fanatic, so it's always nice to be among peers.

Anyway, I'm sure some of you have heard about the V-Verb Pro from Behringer, a rack reverb unit that's a bit of a sleeper/underground hit. I recently picked up this unit in a trade, and to my dismay, it wasn't working. I replaced the power caps, sprayed De-Oxit on all the connectors, and even replaced the foam at the bottom of the I/O board so the component legs wouldn't short out on the chassis. Still, this unit will not pass signal. The LCD lights up fine and all the buttons work, but I can seem to pass a signal.

Does anyone know how I would go about trying to repair this? And please don't tell me "just get a new one". These are getting very hard to find for good reason, and I think I am missing something small here.

TL;DR

Behringer V-Verb not passing signal, need help figuring out the issue.


Thanks!

It does have digital I/O, doesn't it? It is not by any chance set to digital I/O?

Michael

Nope, it's set to analog I/O, just checked. Still not passing signal, even when on bypass.  :'(

first off as a new user we encourage you put where you are writing from, this allows us at large to help you further. For example if you are in southern california around the los angeles area, I would recommend you contact ADS in north hollywood and talk with norick(spelled phonetically). He could easily get you going.

As for servicing yourself,  have you replaced any  electrolytic in the audio path?  The best thing when doing this kind of sleuthing is to visually inspect everything with a careful eye and a magnifying glass. You may have missed a failed part. You could also attempt to feed it signal and probe with a scope to see where it cuts off.

jcdenton825 said:

I recently picked up this unit in a trade, and to my dismay, it wasn't working. I replaced the power caps, sprayed De-Oxit on all the connectors, and even replaced the foam at the bottom of the I/O board so the component legs wouldn't short out on the chassis. Still, this unit will not pass signal. The LCD lights up fine and all the buttons work, but I can seem to pass a signal.

Click to expand...

"Not working" can mean anything. You need, at minimum, a signal generator, a voltmeter and an oscilloscope to verify that the thing has proper power, and then to trace the signal path. Can you do that? Shotgunning power caps is the last thing you should do.

pucho812 said:

first off as a new user we encourage you put where you are writing from, this allows us at large to help you further. For example if you are in southern california around the los angeles area, I would recommend you contact ADS in north hollywood and talk with norick(spelled phonetically). He could easily get you going.

As for servicing yourself,  have you replaced any  electrolytic in the audio path?  The best thing when doing this kind of sleuthing is to visually inspect everything with a careful eye and a magnifying glass. You may have missed a failed part. You could also attempt to feed it signal and probe with a scope to see where it cuts off.

Click to expand...

Hey, thanks for responding! I'm based in Arizona; Tucson to be exact. This is all SMD from what I can see, and I have no idea how to even begin debugging something like this. I may find a guy who can repair it, but that's a longshot IMO.

talk with norick at ADS you might be in AZ, but I am sure you can ship it.  Years ago at a studio I worked for he was the goto guy to fix all the tc electronic stuff, d-two's and m-one's.
PM me for his contact information

Do you know which revision you have?
Some schematics here:
https://www.dropbox.com/s/ipxpgkj7cfb2vnd/REV.%20B.pdf
https://www.dropbox.com/s/mu33h206cugifv3/REV.%20D.pdf

A couple of these units I had required new opamps in the output stage to restore audio output.

You may also find that the black neoprene rubber pads that they stick to the underside of the connector board are stuck over one of the op-amps. Sometimes this can increase the noise in that channel if it starts to become conductive as the glue breaks down.

The unit has 4 modules. The SMPS, a front panel display/button module, a CPU/DSP module (Sharc DSP and ARM processor) and the rear connector module which has the analogue circuitry (op amps) attached to the underside. To get the rear connector module out you have to undo the squillion screws along the back connectors, and then take off the hot snot holding the ribbon connector to the DSP module, whereby you can yank the ribbon connector out and wiggle the rear connector module out. Give it a good check over, most audible problems appear to be on this board.

The PSU in these units also usually requires attention.

It's a SMPS and has a few capacitors that can pop (had one on the bench explode yesterday).
The caps of interest are 470uF/25V and 1000uF/16V.
There are WunHungLo caps in there which have poor specs and should be replaced with better quality electros. Go for 35V on the 470uF caps if you can.
The PSU puts out a few rails, and could probably be replaced with a better quality unit if you are up to it.

Also, recommend adding a small heatsink to the LM317 regulator located on the main board adjacent to the Sharc DSP device. It can get quite hot without it.

gswan said:

Do you know which revision you have?
Some schematics here:
https://www.dropbox.com/s/ipxpgkj7cfb2vnd/REV.%20B.pdf
https://www.dropbox.com/s/mu33h206cugifv3/REV.%20D.pdf

A couple of these units I had required new opamps in the output stage to restore audio output.

Click to expand...

I'm trying to fix my V-Verb Pro right now as well, so, thanks for the schematics!

I want to point out, however, that a single unit contains both "Rev B" and "Rev D" (as far as I can tell). "Rev B" covers the I/O board that runs along the rear of the unit, and also the Display/Encoder board that runs along the front. "Rev D" covers the DSP core, as well as digital clocks and some PSU stuff.

I hadn't powered mine up in at least 6 months, and while it boots up ok, it quickly goes downhill, with the LEDs all starting to blink in random patterns until every single LED on the front panel is turned on. My guess is the power supply bit it when I powered it up after too long a period of disuse... if the power caps are of marginal quality, perhaps they needed to be "reformed" before use? I have the lid off right now, and none of the caps look or smells bad, however.

A cheap lcr meter can let you do a quick check on the various component values. It works pretty well although it can give you hokey readings when stuff is in parallel to a component so, you'd have to desolder them to double check if this happens...... I'd say it's worked 85% of the time for me without having to remove components.....

I agree that caps can really cause problems and see them be bad all the time even if they look ok....... But, I'd definitely replace those generic caps and (go ahead and test them anyhow)....They will fail.......if not already....

Just make sure to unplug everything at this stage......and, if you go checking live stuff later, do be careful careful careful not to short any of those tiny smd components.......

I was repairing one of my Mackie speaker amps and created a day's worth of work with a quick slip of a meter probe.....

Be patient and don't rush anything or get too frustrated..... And keep good track of parts.........You'll thank yourself later.....

Good luck!!!!

PS....It looks like Andy Peters is in your area?????????????????????????

leigh said:

I'm trying to fix my V-Verb Pro right now as well, so, thanks for the schematics!

I want to point out, however, that a single unit contains both "Rev B" and "Rev D" (as far as I can tell). "Rev B" covers the I/O board that runs along the rear of the unit, and also the Display/Encoder board that runs along the front. "Rev D" covers the DSP core, as well as digital clocks and some PSU stuff.

Click to expand...

Yep. I realised that after I opened the schematic files. Should have checked them first instead of looking at the filenames

[quote author=leigh]
I hadn't powered mine up in at least 6 months, and while it boots up ok, it quickly goes downhill, with the LEDs all starting to blink in random patterns until every single LED on the front panel is turned on. My guess is the power supply bit it when I powered it up after too long a period of disuse... if the power caps are of marginal quality, perhaps they needed to be "reformed" before use? I have the lid off right now, and none of the caps look or smells bad, however.
[/quote]

Electrolytic caps in the PSU. Replace them.  It is not always visible damage.
Probably some noise or ripple on one of the rails erratically resetting the processor.

scott2000 said:

A cheap lcr meter can let you do a quick check on the various component values. It works pretty well although it can give you hokey readings when stuff is in parallel to a component so, you'd have to desolder them to double check if this happens...... I'd say it's worked 85% of the time for me without having to remove components.....

Click to expand...

It is usually not the value, since that can be way off anyway with electrolytic caps. It is the ESR that needs measuring.
To do that you need an ESR meter. Usually just as easy to replace the bulk of them anyway.

gswan said:

It is usually not the value, since that can be way off anyway with electrolytic caps. It is the ESR that needs measuring.
To do that you need an ESR meter. Usually just as easy to replace the bulk of them anyway.

Click to expand...

Right about ESR

.  I know I had issues replacing some higher ESR caps post regulator in a unit once. I replaced them with low ESR  Panny FRs and couldn't figure out why I was having problems......Come to find out, that part of the circuit needed the higher ESR caps to function right....

But an LCR can check for resistors and  caps that are bad. Not for leakage and ESR but, obviously out of tolerance..... or worse....

But yes, those electros should be replaced if they're all cheapo..........Just be mindful of not damaging any traces or other components if things get a bit tight in some areas... Sometimes the risk to reward isn't what you may want..... if the caps are fine....


Good Luck!

gswan said:

Electrolytic caps in the PSU. Replace them.  It is not always visible damage.
Probably some noise or ripple on one of the rails erratically resetting the processor.

Click to expand...

I got lucky with the fix! I pulled the 7 pin header (named "X2") off the DSP board, that carried power from the PSU. Poked around on that with a voltmeter, looking to map the different voltages coming from the PSU. Didn't get anywhere with that, as the voltages measured strangely... applying the meter, I would see a brief DC voltage which would quickly run down towards zero. I figured it wasn't behaving correctly while disconnected, so I re-attached the header to measure things in situ.

To my surprise, once reconnected, the unit powered up fine and stayed stable. I left it turned on for a couple hours, and no crashing... definitely a different behavior from before, when the crashing would happen within a minute or two.

So seems like dirty pins of X2 might have been giving trouble. I pulled it off again and used contact cleaner, so I'm hoping that will provide stable operation for the time being.

I agree that it would be ideal to replace all the electrolytic caps in the PSU, and if there were just a pair of them I'd go for it. However, there are 10 of them in the PSU, and so I'm going to leave that be unless it starts behaving erratically again.

Also, that SHARC chip (IC13) runs hot, but apparently that's in spec. I got a thermal reading of 122°F off the top of its case, which I was initially worried about, but its datasheet lists a max temp of over 212°F.