Author Topic: No sound in boost mode :(  (Read 4482 times)


No sound in boost mode :(
« on: July 18, 2010, 08:08:21 PM »
Hey guys,

I was hoping you could help me troubleshoot the NPN Simple Boost, which is proving to be not so simple for my first build.  :icon_mad: I've learned alot so far, but I just can't figure what I did wrong.  I stuck to the parts list for the most part - one of the 100k resistors was swapped out for an 80k resistor and the 22uF electrolytic cap was replaced by a 25uF, oh and I used a 2SC1849 tranny.  I get sound in bypass, but when I engage the switch, I get the LED to light up, but no sound thru the sweep of the pot. 

Here are the voltages I am seeing with my DMM, slightly off of whats on that thread, but pretty close:

9V: 9.12
C: 5.69
B: 3.05
E: 2.45
10k/100k/47k: 3.12

And here are some pics of the board itself.

Besides some sloppy joints, can you guys see where I went wrong?


Re: No sound in boost mode :(
« Reply #1 on: July 18, 2010, 11:37:14 PM »
You could do a "tap" test.
Switch in the circuit and start tapping with a meter or any other metallic object on the junction of the 10uF output cap and the 100K to ground. Listen for the signal in your amp - you should hear the tapping. If you don't, it's probably your switch wiring.
If you hear something, move backwards - tap before the 10uf output cap where it meets the collector.
Then tap the base of the collector etc... You should hear your taps, otherwise it's a wiring mistake right in the circuit.



Re: No sound in boost mode :(
« Reply #2 on: July 19, 2010, 12:48:51 AM »
Thanks Aron,

As always, your help is greatly appreciated!!! Immediately after posting, I remembered I had a signal tester where I could use my amp to see where signal stopped passing.  It was the Collector / 10k junction.  I tried reflowing the solder, but it still didn't work.  So I removed a bunch of solder, pulled that resistor and the socket, cut a new 3-hole socket and replaced the 10k.  Not sure which was the actual cause, but something was wrong with one of those components.  I soldered everything in place and it fired right up!  Probably won't use it on the board, but I am proud of my first DIY.  It gets progressively louder and then distorts nicely at the end of the sweep.  Cleans up nice on the guitar's volume knob too.  I should put it after an OD or fuzz and see if I like it.  Also tried using a 2N5133, but it was noticeably quieter and didn't get near as much breakup out of it.  The enclosure is a blem Pedal Parts Plus powder coated discount-dealie that I drilled with a unibit.  Not perfect, but not bad.  Anyway, here are a few shots:

Next up - a PNP fuzz face followed by / along with a Ruby 9V amp.  Running back and forth between the garage and the music room proved to be a pain during all the troubleshooting!


Re: No sound in boost mode :(
« Reply #3 on: July 19, 2010, 12:51:46 AM »
Congratulations! This booster sounds really great in front of an amp like a Carr. I also like it with my Fender Bassman. It really adds a great tone when used in front of my pedals.


Re: No sound in boost mode :(
« Reply #4 on: July 19, 2010, 11:00:15 AM »
Thanks again, Aron!  Not much quite as satisfying as raising a dead pedal from the scrapheap.  I was using it alone between my strat and an old SF Vibro Champ.  I'll definitely try it out in front of my dirt pedals.


Re: No sound in boost mode :(
« Reply #5 on: July 19, 2010, 03:07:29 PM »

In my case, I can hear a nice difference when using it in front of my old 64 bassman. Just my Suhr->booster->Bassman. But my Bassman has been re-voiced.