Dragonfly's Bassman Fetzer - has anyone built this successfully?

[jcuempire]

I built the Bassman Fetzer and for the life of me, I can't get it to work.  I went through all the obvious potential problems and I am coming up short.  I want to make sure it's been verified so I know to keep going.  Thanks

Keith

[Haynesarama]

Hi There.

I've tried to look for a layout, Which one have you used?
Any chance you could upload it or add a link to the one you've used.
Some advice though, Triple check for solder bridges, Triple check the transistor pinout and polarity of the electrolytic cap.

Cheers
Michael

[danielzink]

is it this one:
http://aronnelson.com/gallery/main.php/v/DRAGONFLY-LAYOUTS_0/album17/album06/BASSMAN_FETZER_VERO.gif.html

did you adjust the drain for 4.5v ?

http://www.aronnelson.com/gallery/main.php/v/PenPens-stuff/Bassman_Fetzer.png.html


Dan

[jcuempire]

Dan & Michael,

Thanks for the response

The one Dan is linking is the one.  I checked and rechecked for solder bridges and the electro cap and the J201 are correct.  The weird thing is I am getting almost full power at the drain and the trim pot changes it very little.  So I am figuring I messed something up.  But I have looked at the layout over and over and I believe I have it right.  The next thing to look for would be incorrect values of the components, I assume.   I put a 47k as R2 and 2 parallel 100p caps for C2 simply because that's what I had on hand.  I get bypass so I know the switch and everything is wired correctly

[danielzink]

did you double (double) check all your cuts (9 of them) ?

[jcuempire]

That was a good idea.  I was hoping that was the case.  But I checked and I have the right number and in the right place.  So I re drilled them just in case there was some errant copper making a connection, but no dice.

Keith

[Haynesarama]

Hi Keith


If you've got a DMM with continuity on it. You can check to see if you've made any solder bridges or connections anywhere where you shouldn't have.
Sometimes when you've been looking it over for a while you skip things you normally wouldn't, I often do when debugging 
Any way of uploading a few close ups so we can see whats going on?

Cheers
Michael

[jcuempire]

Thanks.  If I can get a decent picture of it, I will post it.  And I am sure you're right that after a while it becomes nearly impossible to notice certain things.  Thanks again

[theundeadelvis]

Are you certain you have the correct value trimmer and that it is functioning properly too?

[Earthscum]

If you're suspecting solder bridges, check the ends of your board. I've never used vero, but there have been reports of the ends being bridged together with a thin strand at the edge of the board. If you take a knife and scrape the edge down, or a piece of sandpaper, just chamfer the edge to make sure all the tracks are separate at the ends. GL

[jcuempire]

Are you certain you have the correct value trimmer and that it is functioning properly too?

It is the correct value.  I have about 10 of them, so I could swap it out if only to eliminate the possibility

[jcuempire]

If you're suspecting solder bridges, check the ends of your board. I've never used vero, but there have been reports of the ends being bridged together with a thin strand at the edge of the board. If you take a knife and scrape the edge down, or a piece of sandpaper, just chamfer the edge to make sure all the tracks are separate at the ends. GL

Thanks.  I checked that as well.  But I cut it out from the center of the board so I didn't have any factory edges. 

I may have to put this one aside.  I have been having about a 50% success rate with vero.  But I built the original Fetzer Valve (http://aronnelson.com/gallery/main.php/v/DRAGONFLY-LAYOUTS_0/album14/album143/ROG+FETZER+VALVE+VERO.GIF.html) and it sounds great so I am anxious to try something else in that vein.

Thanks for all your help

Keith