Behringer ultratone k450fx noise issues

[nosaj]

I've got a Behringer ultratone K450fx that seems to have some digital noise(hash) intermittantly after about 30 minutes of play. Turning the FX level to 0 kills the noise . Looking for some suggestions of what I might should be looking for or what to monitor. Behringer+k3000fx.pdf

thanks, nosaj

[nosaj]

I've got a Behringer ultratone K450fx that seems to have some digital noise(hash) intermittantly after about 30 minutes of play. Turning the FX level to 0 kills the noise . Looking for some suggestions of what I might should be looking for or what to monitor. [ATTACH]58566[/ATTACH]

thanks, nosaj

Ok probably not the correct schematic, but looking at the fx processor it seems to me I should monitor the 5volt and maybe 15 volt rail an see which one goes wonky and proceed from there.

nosaj

[Enzo]

Freeze spray? If that stops the noise, then narrow it down. You can use a 3x5 card or even a sheet of paper to form a shield, so you can keep the spray only in certain areas. You can even roll it into a tube and put it around a single part, and blip a little freezit down in there.

[nosaj]

Freeze spray? If that stops the noise, then narrow it down. You can use a 3x5 card or even a sheet of paper to form a shield, so you can keep the spray only in certain areas. You can even roll it into a tube and put it around a single part, and blip a little freezit down in there.

At the risk being a moron which area might you suggest freezing....definately not the 5 v regulator as that would crack it , it it were over heating , no?

nosaj

[The Dude]

I've never cracked a part with freeze spray. Regulators, processors, etc. can get hot. You could start with the finger test first. See what's getting hot.

[g1]

I think monitor the supply lines as you mentioned. Look for dropping voltage or ripple when the problem occurs.
If the supply lines stay solid, no need to freeze the regulators. (though I've done it and never cracked anything either)
Once supplies are verified good try freezing other chips in FX circuit.

[Enzo]

I have never had a part crack from freeze spray. It isn't liquid nitrogen.

Turning FX to zero kills the noise, so to me, power supply is on all the time, so I am led to suspect the analog FX circuits. I have no idea where they are on a board. So with the thing running and noisy, I just spray the whole darn thing. Does that stop the noise? If so THEN spray smaller areas. We narrow it down to smaller areas until we find something sensitive.


COuld be signal path, could be power supply. That is what freeze spray is made for. it isn't for cooling your coffee.

[nosaj]

I have never had a part crack from freeze spray. It isn't liquid nitrogen.

Turning FX to zero kills the noise, so to me, power supply is on all the time, so I am led to suspect the analog FX circuits. I have no idea where they are on a board. So with the thing running and noisy, I just spray the whole darn thing. Does that stop the noise? If so THEN spray smaller areas. We narrow it down to smaller areas until we find something sensitive.


COuld be signal path, could be power supply. That is what freeze spray is made for. it isn't for cooling your coffee.

Canned air upside down a suitable sub for freeze spray?
nosaj

[Enzo]

yes, better than nothing.

[The Dude]

FWIW: I worked on one of those not too long ago with similar symptoms. It ended up not being the effects that were the cause. There was a shorted op amp on one of the inputs sending hash to the effects board. The effects circuit was just doing what it's supposed to do. I'd first make sure all of your inputs work. If they do, then move on to the effects circuit. If not, fix any non working channels first.

[nosaj]

FWIW: I worked on one of those not too long ago with similar symptoms. It ended up not being the effects that were the cause. There was a shorted op amp on one of the inputs sending hash to the effects board. The effects circuit was just doing what it's supposed to do. I'd first make sure all of your inputs work. If they do, then move on to the effects circuit. If not, fix any non working channels first.

All inputs working, once opened I see the board is an lpa145 here be the schematichttps://diagramas.diagramasde.com/ot...PA145_RevG.pdf
nosaj

[nosaj]

All inputs working, once opened I see the board is an lpa145 here be the schematichttps://diagramas.diagramasde.com/ot...PA145_RevG.pdf
nosaj

Replaced c9 and c5 for the 5v supply . Reasoning being based on the k3000 schematics its DSP module used 5v so I inferred the same here. And knowing that Digital requires a much cleaner DC than analog I replaced c9 and c5 and after 4 hrs no electronic hash noises.

Case closed only thing is now I have to sell it.

nosaj