Build Your Own Clone Message Board

Stalled build ( misplaced ICs a month ago:( , now getting finished with re-ordered parts.

Quick/preliminary power-up showed both switches triggered their LEDs as expected, so I started wrapping up build.

When I was finally ready for sound check, the BYPASS/ON LED failed to glow upon switching.
Really seemed the EFFECT itself was functioning on/off per the switch, but I didnt have much play time , cos...

a few more minutes later, that LED sputtered to life ; flickering , then steady normal glow.
Sound effects seemed to work. ( could toggle Ringer, switch to Bass-only, didnt have much time with MIX & TONE) . Joy abounded.
Sound volume while "BASS ONLY" mode WAS hugely diminished, would not be able to use that BASS ONLY operation along with other functions ( way too quiet) ,
although putting the pedal BEFORE my the compressor helped a little.

Within 10 mins & still dicking around with too much stuff / not yet familiar with effect, the LED started flickering intermittent & went mostly off.
Watching the thing about 10 minutes showed LED had a mind of its own; random on, off , flicker, die, on , whatever ... . No joy no more.
Really seemed the effect worked whole time . ( question - would "EFFECT WORKING be impossible IF there was a problem on that branch of circuit?)

I began dismantling to look for issues, and seems LED fully DOA now , not sure about effect function, & unit is picking up a little damage ( wires breaking) from clutzy handing

The affected LED & associated circuit is boxed in red on attached schematic .

If any one can explain the function of that segment of the circuit, thanks. I maybe an engineer but not THAT kind of engineer.
I was surprised to see that much circuitry hangin off the LED's trace into SW1C. What the heck that do ?


I grabbed some quick voltage readings across the problem-LED while it was doing the deeds. May revise this data later if I can capture it again.
don't shoot me if these are wrong but seems;
Switch OFF, i recall yielded .6 V across LED.
Switch ON / LED ON = voltage about 2.0
( Q? : is that measure voltage diminished by the threshold voltage of the LED ? I thought this red LED had a higher threshold V than 2, so surprised it would turn on at all ...
Switch ON / LED DARK ; voltage around 1.9 , not huge different , but definitely lower .

I ordered some small doses of the BS170 and 2N3904 , even some of the D8 diode, to swap out for trouble shooting , plus some snap-off SIP sockets ,
because Im concerned that Im over-heating the transistors with too-enthusiastic soldering.
Wondering about that on several kits, for various reasons to write up later.

Comment / advice / insights welcome, but until I get those transistors swapped & pedal back together, I probably wont get to re measure.
All I have is a decent VOM to check, nothing I could see fast switching with ...
Yaah I know the usual culprit , but the soldering / wet -out / etc sure looks is good . almost toooo good.
Hence , Im worried I fried some transistors by working too hot.

The problem was not 'physical' ie tapping / wiggling , moving switch wires, etc ; all that was fine until I removed from enclosure and started dicking around w/it &inflicting damage.

This is called "millennium bypass". It utilizes the circuits low impedance output to turn the LED on and off. When the pedal is "on", Q8 and D8 apply a voltage to the gate of Q9 to allow it to "open" and turn the LED on. When the pedal is "off", lug 7 of the footswitch connects the gate of Q9 to the output of the circuit. It's 100k ohm impedance is low enough to cause Q9 to "close" and turn the LED off.

Anyhow...an intermittent problem like you are describing is almost always caused by a faulty solder joint. You've already gone and removed all the semi-conductors associated with the LED. You'll likely fix the problem when you replace them. Also make sure to reflow the solder joints on R64, lug 7 and eyelet 7, and the actual LED itself.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

thanks for reply, did some more work on it, but back sliding ! (I have not pulled any trans/diode components yet ... )

I do believe your experience ( "solder is usually the problem") but my components solder is solid (wetted pads both sides, solder wicked onto component leads, checked under magnification. Bright shiny PbSn , every single joint) . I'll be adding some pics here for the sharp eyed soon.

I did my best to 'test " all the switch wires for intermittance, but got no sign of problem, so I pulled the board out of the enclosure,
Pulling the board out of the enclosure was pretty hard on the board-to-jack wiring, had some detached at solder ( brittle point) .
Weak wires sure could have been present before but I think they were stressed from handling & fractured

Pedal now acting different ...
but after replacing all the wiring on that switch, NOW I got an LED that responds to the switch, but no working FX-sound ¯\_ (ツ)_/¯, just silent when ON
The BYPASS functions ( OFF setting passes dry guitar )

I have not removed any trans or diodes yet ...I (crudely) thought the odd voltage action was a sign
if I recall ( V across diode legs)
2V@ SWITCH ON / LED on
1.9 ( or less ) with SWITCH ON / LED dark (non op) .
0.6V with SWITCH OFF / LED off


My component soldering is pretty good and closely inspected, work with magnification .
I wonder how easy it is to heat -damage a transistor, I tend to reflow a lot, too much by most accounts....
Im in an out fast with a good hot iron & sharp tip , but still wonder if I cooking a trans.
WOndering if it is worth the trouble to SIL the transistors now & future ..
Will a VOM be sufficient to find faulty trans ?

pics soon