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Shoot The Moon - Problem Solved... Thanks!!

Started by frankie5fingers, October 06, 2012, 06:39:33 PM

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frankie5fingers

Hope it's OK to use this forum, but I've seen other posts on these, so...  I'll move it if need be.
Anyway, built a Shoot The Moon.  It's a clean build and it works... sort of.  It passes signal on or bypassed, the volume is good switched on or off, and the tone/signal is pretty much the same bypassed or switched on etc., but....  Neither D1 nor D2 lights up.  D1 is mounted outside to indicate pulse, and D2 is the one facing the LDR.  I had a post a bit ago and I thought CJ said both D1 and D2 have their LDR's built into the board - did I misunderstand? I socketed D2 and tried another but no light with that one either.  There's no trem effect, just the un-effected tone.  When box it up, the signal stops, open it back up to light, it passes signal again, on and of course, bypassed it passes the signal unaffected.  Switched on, if I cover the LDR, it gets progressively quieter until I cover the LDR completely and it stops again.  I'm completely unfamiliar with LDRs and light based effects so please pardon my ignorance.  This is the LDR I bought:
10x LDR photo resistors - Resistance changes based on light exposure
Bright Light = Roughly 1k or less of resistance
Complete Darkness = 2 Megaohms or higher

Did I buy the wrong one or, is the fact that the LEDs aren't lighting where the problem lies?
Thanks, Frank

midwayfair

Your LDR is fine and functioning correctly. Your audio path is also correct.

D2 is the LED that faces the LDR. You have to point it toward it, and it's best to wrap it in some electrical tape.

D1 is an indicator LED. That one goes outside the case.

There are a few reasons why the LEDs might not light up, but here are the things to check:

1) Make sure they're oriented correctly.
2) Double check the value of R8. Make sure it's 470 OHMS, not 470K. That would drop the voltage too low to activate the LEDs.

If these don't work, take clear pictures of both sides of the board and measure the voltages on IC2. If you aren't sure how to do that, check the tech help thread, it has tips on troubleshooting.

frankie5fingers

#2
Hey Jon.  Thanks for the reply.
Sorry, I'm saying D2 to the outside and D1 to the LDR, but I mean the opoosite.  I checked, R8 is a 470 Ohm but just to be safe, I swapped it for a new one.  Then reswapped (is that a word?) the LEDs both ways again; no change.  Light in = sound, no trem, but unity sound.  Block the light = no sound at all.  No noise, but no trem either.  Of course bypassed same tone/sound.  Hmmm.
I can't figure it out.

mjcyates

I built one of these and had issues at first and then realized the led orientation was backwards on the board. Try changing the orientation of the led's and see if that works.

frankie5fingers

Hi Marvin, thanks for the reply.  I've tried 'em flat side round pad, and flat side square pad.  According to the build doc, the long leg (round) should be square pad right?  I'll swap 'em again, it's definitely possible I thought I switched them but just reinstalled the same way.  Which way did they work for you?
Thanks again, Frank

jkokura

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midwayfair


frankie5fingers

Just got the LEDs to light Jacob.  In the open D2 is bright, D1 (outboard) not so much.  Now that they're lit though, the gain pot is scratchy and though it's wired according to the board's 1, 2, 3 pads it seems it may be backwards - with a slight increase counterclockwise.  It was a new pot but wouldn't be the first time I got a bad one.  I used a B5K, according to some posts I saw saying that tamed some higher than unity volume issues.  I can't imagine how changing to 5K would be a problem, no?  Any chance the gain pads (others too?) are backwards from the build doc too?  I know eveybody, including Dr. Joyce's brother (that'll be funny later) loves this thing... I want to hear it.
In any case, I'll swap that out tomorrow.

frankie5fingers

#8
I had the LEDs lit briefly, not sure why.  Based on some posts here and at BYOC, I guess I've established that they are installed correctly with the cathode to square pads.  I swapped them for LEDS that I know work (THX Jacob) and replaced the B5K gain pot with one that I know works (THX Jon) and now:
It passes signal completely when switched on, but only with the the LDR exposed to light, when boxed up or covered, the signal stops.  Neither D1 nor D2 will light.  When opened up, the signal is completely unaffected by any knob except the volume, no other knob works.  They all make a noise when tapped.  The LED and LDR make a sound when I lightly squeeze my fingers over them so obviously they're controlling something.  Not great pix but here's a shot of the top and underside.  BTW, not sure if it matters, but I used a 3PDT board to wire the stomp.
Any help is appreciated.  Thanks, Frank

midwayfair

Looks like R16 is wrong. It's supposed to be 100R.

I made the EXACT same mistake on my first STM board. I had already desoldered most of the board before I found the mistake, too.

frankie5fingers

...and Jon said, replace R16 with the correct value and there will be light...
and there was light... and tremolo!

Jon, I was just about to remove all components and start again.  Many thanks, that was the right call.  I checked but missed it twice, so I wasn't looking at those anymore.
It works, and sounds great.
Thanks (once again) to everyone for the help!!
Frank