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.
Attachment:
divided octave schematic - 1 (1).jpeg [ 228.07 KiB | Viewed 740 times ]