Boneyard issue

[Vintageman]

Hello

I'm experiencing some problems with my boneyard. The power section is OK. I measure +9v in pin 4 of the LF347, and -8,80v in pin 11. Ground is Ov.

All the remaining pins of the LF347 are 0v, except pins 8 and 9. I've measured -5.80v in pin 8, and -5,67 in pin 9.

I've done double check of the tracks and components. Everything seems to be all right.

The negative values of pins 8 and 9 are caused by the LF347, if I take off the chip, the voltages goes to 0v in both pins.

I've replaced the chip two times (I only have 3 LF347´s available by now), but all of them shows the same behaviour. I'm mystified.

The signal reaches the vol pot. but in pin 9 of the 347 a noise appears, and you can still hear the signal, but noisy.

Any idea of what could be happening?
thanks folks, best regards.

[Vintageman]

OK. Solved. Pin 10 was not properly soldered and wasn´t touching ground.

But now I´m hearing the typical oscillation. I´ve done the R5-C5 mod, the R4 under the PCB mod, shielded wire for in, out, fx in and fx out, but the oscillation remains...

I´m going to re-check all once again.

[mgwhit]

But now I´m hearing the typical oscillation. I´ve done the R5-C5 mod, the R4 under the PCB mod, shielded wire for in, out, fx in and fx out, but the oscillation remains...

In my experience, none of those mods will get rid of the oscillation (although the R5/C5 Gain mod does lower it a bit).  Try a putting a buffered pedal in front of it (anything by BOSS will do nicely).  If that kills the oscillation (and it should), you can add any number of JFET or op-amp buffers to the circuit input to make the solution more permanent/portable with minimal effect on tone.  Good luck!

[Vintageman]

hahahaha It works!!

Thank you man. The main whistle disappears using a buffer. It remains a softer whistle, I don´t have by now another buffer to test it. Do you think that using 2 or more in series the softer whistle could disappear as well?

[pryde]

Look in the mods section, I posted a very simple klon buffer on vero you can build that should remove all the problems. I experimented with several buffers and this one worked great. Good luck

[Vintageman]

Ok, I´m going to try it just now, thank you man!!

[Vintageman]

HEY!! NOW IT´S DEADLY QUIET!!!!

THANK YOU PRYDE.

Even I´m using 1M/100K for high gain/crunch pots.

I´ve had to reduce the booster pot from 100k to 50K, because it was squealing, but now all the whistles have gone.

I´ve been struggling with this box for a long time!!

Thank you man.

[pryde]

Awesome' glad it worked out 
The Boneyard is WELL worth the bit of extra work to get it perfect.

[Vintageman]

Yesterday I was testing the boneyard in the soundcard. But today in the amp I´ve realized that still remains a whistle with the all the knobs full clockwise, with boost and high gain activated.

I´m using by now:

-Shielded wire
-R5/C5 half gain mod
-50K-B pot for boost
-1M-A for high gain
-100K-B for crunch.
-all metal film resistors.


I suppose I need to use a 25K-B for boost to completely kill the squeal.
I´m seriously thinking in using a transformer, like the original carl martin, and get rid of all the anti-whistle mods.
Does anyone have tried something like that?


Thank you again, guys, for your help!!!

[Vintageman]

Something happened, I think I could have done something wrong in the boost section.

Now with the FX off (working in true bypass), if I activate the boost, a whistle appears. This is really weird.

By now, I´m going to recheck all again and investigate it.

[Vintageman]

Another idea.

I´ve realized that the output level of this box is really high. Maybe raising the value of R8 we could finally get rid of the oscillation loosing a bit of output level. (that we have too much). And maybe we could remove all the anti-squeal mods (except the buffer of course).

It´s time to think a bit about what way I´m going to take.

Of course all your advices guys, are highly appreciated.

[alanp]

Trainwreck Expresses sound like they're easier to get going, legendary lead dress issues and all.