Nabo's Mini-head/Talkbox Amp - Builder's log / Q & A

[NaBo]

THANKS!!!!!!!!  

The tab is screwed to a pretty sizeable heatsink, but this doesn't appear to be connected electronically to anything (other than the tab).  I'll be sure to continuity check everything after removing the chip, which i think is the most likely cause of the short, and before plugging this thing in again.

I'm heading back to the big city next saturday, so I'll pick up couple TDA2030s for dirt cheap with my first parts run of the semester.  (Not having to walk more than a block for parts that will cost you less than ordering online is such a luxury!!!)  Hopefully the chip and diode replacement will be enough to get this thing up and running...  In the meantime, I've gotta get the little box for the horn driver assembled!!!

[R.G.]

As a bit of belt-and-suspenders, you might get yourself a to-220 insulator and a nylon screw the same size as the existing metal one. If you do this, you can insulate the 2030 from the aluminium heat sink and make yourself immune from future disasters involving grounded things touching that aluminum heat sink. I bet that a well stocked parts source as you describe will have the Sil-Pad thermally conductive rubber insulating pads for the TO-220 package.

This will make the 2030 not care whether the aluminum heatsink is grounded or not. It will cost you a little in terms of thermal performance, but for a talk box, you're not going to be pushing it to maximum warp drive anyway.

It's just a thought.

[NaBo]

Well!  Finally had a sec to poke at this thing again!  Replaced the TDA2030 and a couple diodes, and im no longer popping fuses.  I continuity tested the old chip-  yep, continuity between 3 and 4...  there's my short 

The thing powers up okay now, but the bypass LED aint working and no sound yet.  I'm probly gonna re-wire the switch, i wouldnt be surprised if thats my problem is since i was really sloppy with it...  Probably a shielded wire grounding input or something.  Before i wire anything back up, i'll test it with input going straight to the board.  Can't wait til i can FINALLY screw the lid on this thing and plop it on my cab for a while.  Yeesh.

But alas... working in addition to school this year so I'm really guitar-gadget-fiddling deprived for now. 

[NaBo]

*RESURRECTION!!!*   

It's ONLY be a couple of years!!!    Separated all the wiring from the board and continuity checked them separately...  Board is fine now, wiring was bad-  The shielded input wire by itself showed continuity between the inner wire and the shield.  Must have melted the inner insulation while I was soldering it to the switch many moons ago.  Gator clipped a guitar and speaker to the board just to double check everything else was okay and it works fine.  Rewiring tomorrow, but better this time!  hahah

[NaBo]

FINISHED.

I rewired today and tested it every step of the way so I'd know exactly what was wrong if anything went awry.  Well, when I affixed the PCB to the chassis and fired it up, I cooked my 2030.   

Turns out the metal posts I was using to mount the board had worn through the mask on the PCB and were shorting a couple traces to ground.  WONDERFUL!  I replaced them with crude little plastic posts made from drywall anchors and stuck in an extra tda2030 that I had purchased in a brilliant flash of foresight.  Stuffed it all in and finally, here it is, my little practice head/talkbox amp!



Gonna start working on a little enclosure for the talkbox driver now

[syndromet]

NICE!

[Stompin Tom]

Wow. Congrats... I'm amazed at your persistence both in finishing this project and updating this thread for years!