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Vetta Head no Output
by Motorco on 2012-05-28 18:51:57

So I finally got around to plugging in my second Vetta Head I bought in late march off eBay....I was about to move, so just kept it boxed and moved...then setup my music room. Got an A/B Box to run both heads.... I cannot get any output. I have it set up exactly as my other head. Nothing, no sound comes out. I took everything out of the loop...ran guitar direct and a mono out to the cab to test, nothing. I can plug into the amp and use the tuner, so I know a signal is going in... but nothing coming out. Any help or anyone experience the same thing?

Re: Vetta Head no Output
by DickFoster on 2012-05-29 09:56:41

I know it's a long shot but have you checked the settings under System Setup to ensure that the output is enabled. Have you checked with headphones. Sometimes the simple stuff can give you your very best clues. After that maybe check for output at the loop output to see if the trouble is in the front end or the back end. i.e. preamp or power amp. 

Re: Vetta Head no Output
by Motorco on 2012-05-29 10:52:35

Yep output settings are on...I just tried direct out, using my XLR outputs and I get a signal...and the master volume on the front works....

Re: Vetta Head no Output
by DickFoster on 2012-05-29 14:11:39

Well then in that case you've pretty much eliminated all the preamp and digital stuff. A good thing.

Have you tried a pair of headphones by any chance? However at this point, I'd be leaning toward a power supply or final power amp problem, tending toward a power supply malfunction of some sort as they typically tend to be more failure prone. The Vetta power amps are built with power MOSFETS which are fairly rugged components compared to other power amp designs and components. Power supplies and such are also typically easier circuits to troubleshoot and isolate problems in for technician types. 

If you're at all a technical electronics type or have a friend who is, I can point you to a service manual online that you can download. But unless you know what you're looking at it, it wouldn't really be worth while to down load it because it would be like trying to decipher ancient Egyptian hieroglyphs.

For what it's worth, I think the Vetta is a high quality amp that is very well built and designed and I've seen a lot of electronics stuff in my life.

Re: Vetta Head no Output
by Motorco on 2012-05-29 16:23:22

The head does not have its own headphone out. I used my headphones with my Beringener 802 mixer. Sure point me to that Manual. I have already found a local service center, just in case. Thx

Re: Vetta Head no Output
by DickFoster on 2012-05-30 09:05:16

Sorry for the confusion. I have a combo which does have a headphone jack. Odd that they didn't include it in the head unit.

However that does raise a question. You don't think that someone could have perhaps done a software upgrade and used a combo amp file instead of the code for the head unit do you? Other than the amount of power output, that is one of the few electronic differences between the head unit and combo.

There is a pin on one of the DSPs that senses whether or not the headphones are plugged in, if they are plugged in, it shuts off the power amp. If someone did an upgrade using the combo code instead of head unit code, the DSP would think that headphones are plugged in all the time and shut down the power amp and kill any speaker output.

The power amp mute output pin from the DSP1 chip is pin 80. If it's low it says to shut off the power amp so it has to be high for the amp to work. The headphone input sense pin of the DSP is pin 134 which for a head unit should be ignored if the right code was used. 

The amp mute function can also be checked on the base of Q25 on the power amp PCB. If it's low, the amp will be muted so it has to be high so that FETs Q30 and Q31 will be on to pass audio on to the power amp.

Re: Vetta Head no Output
by Motorco on 2012-05-30 18:07:03

Thx for the link...I took it out of the box and plugged it didnt work. So I upgraded everything, because for some reason the MIDI ports would not be recognized. After I updated the firmware and reset back to factory defaults, it still would not work.

Re: Vetta Head no Output
by DickFoster on 2012-05-31 14:30:57

How did you get it to upgrade with inoperative MIDI ports?

BTW I would not suspect and digital problems since you had output and the loop output. I would suspect the power amp or a power supply but as this is a stereo amp the likihood of both amps going out at once is somewhat remote so I'd look at a power supply problem first. Look for a missing voltage to the power amp section that is used only for the power amp and nothing else. 

Re: Vetta Head no Output
by Motorco on 2012-05-31 18:59:12

It would show up in Line6 monkey but not in Line6 updated the firmware and then it showed up in Edit

The information above may not be current, and you should direct questions to the current forum or review the manual.