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hi I making a univibe from GGG schematic and pcb I etched. well I soldered everything and now it doesnt work. I checked solderings and  parts to be correct but voltages of Q11,Q12 and Q13 are not right and I cant realize why? any ideas?
votages:
Q E B C
1 1.01  1.4 1.98
2 1.06 1.97 4.38
3 3.78 4.4 11.61
4 4.43 4.83 15.5
5 3.83 4.43 15.5
6 4.57 4.96 15.53
7 3.97 4.57 11.3
8 10.7 11.3 15.53
9 10.01 10.7 10.2
10 6.5 7.03 15.5
11 7to13 6to11 18
12 7to13 6to11 18
13 2.5to4 3to5 18
i think Q9 is not right too
2
Few years ago, I used a bank of aged (over 40 years old) electro caps (20 X 3,300μF/50V) for a power supply reservoir.. PS iddle current was calculated at about 55mA.. When measured, it revealed over double..!!
Didn't put the blame on caps leakage till all particular stages measurements made me to do so.. :icon_wink:

P.S.
Didn't have the time to observe leakage variation (if any) in relation with duty cycle / load current..
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Digital & DSP / Re: Arduino MIDI Switcher
« Last post by Sweetalk on Today at 05:30:29 AM »

When you could use this:

Code: [Select]
MIDI.sendControlChange(c,v,0xB0 | midi_channel);

Just a little correction, you have to use midi_channel directly, like this:

Code: [Select]
MIDI.sendControlChange(c, v, midi_channel);
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Digital & DSP / Re: Arduino MIDI Switcher
« Last post by potul on Today at 05:26:07 AM »
Nice,

just a comment: you are using the MIDI library but not using the sendControlChange() function and instead you are accessing Serial directly. Any reason for that?

In my tests when trying to use the switches to change the channels, it actually wasn't working at all and I was scratching my head wondering what exactly was happening... and also because this was my first or second sketch, I'm not exactly proficient in coding at all...

but I wanted to be able to use standalone switch functions without a midi footswitch, if I decide to incorporate it into an amp pcb design, and as the other way wasn't working, I got a little creative

Not sure if I get the point. My question was regarding using this:

Code: [Select]
  Serial.write(0xB0 | midi_channel); // CC message
  Serial.write(c); // number
  Serial.write(v); // value

When you could use this:

Code: [Select]
MIDI.sendControlChange(c,v,0xB0 | midi_channel);
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Capacitor Plague. Affected even the higher quality brands. The back story I heard is it was industrial espionage gone wrong. Someone took the wrong improved electrolyte formula with them to a new job.

Back in the 1980s, the place I worked at did goods-inward leakage tests on large PSU caps. Someone made a rig to reform the failures. Then I learned that you can reform an aluminium electrolytic in reverse polarity if for some unfathomable reason you wanted to. It's only the original forming that gives it the marked polarity.




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The bypass on this one is quite unusual.  Not the typical Boss buffered dry path and effect path that is alternated with FET switches. In this one, the dry is always on (provided nothing is plugged into the ‘direct out’), and Q8 mutes the delay sound going to the level and regen pots. Muting the regen in bypass is nice. So is the FET switching because it fades in over a few ms and doesn’t pop and send pops through the regen when you turn it on.

If a plug is plugged into the ‘direct out’, Q5 mutes the dry in the dry/wet mixer at IC1a, but unmutes the dry when in bypass, opposite Q8.

The bypass signal does go through a lot of stuff, not just the buffer, but a pre-emphasis (IC1b) and de-emphasis (IC1a) that I didn’t notice sounding terrible on my DD2, but, I don’t think it is crazy that guitarists might object to having to run through all that stuff in bypass.

There’s a bunch of functionality that is lost by true bypassing by disabling the FET switching and BA634 flip flop- you lose muting the regen, you lose the popless transition when the delay gets switched on, I’m pretty sure the hold won’t work right because the there is no input to the delay buffer before you hit the switch, and the relay doesn’t know to switch momentary in hold mode.

A ‘truer to the original design’ way to do a relay bypass would be to do the classic “tone sucking” bypass, where you are always feeding the effect input, and switch the output jack from pedal input jack  to effect out, with one SPDT switch.  Don’t worry about tone sucking because the input impedance is nice and high, 1M. Control the relay with the 0/+9v logic at wire connection #1 on the SW BOARD (the common of S1 Mode switch, top throw on the schematic).

That logic has the bypass to go with the LED, and does the momentary thing when in Hold mode.  Also in this configuration the direct out works as intended, making the effect output wet only, when a cable is plugged in. Hold mode should work right because you are always feeding the buffer.
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Yeah it's interesting, I was working on MTTF (mean time to failure) calculations the other day and discovered that every 10degC increase halves the lifetime of an elco. Imagine putting them very close to an LDO that's running very hot and that in a closed box (a pedal xD)...  :o
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Ah, I see. The switching is done with IC9, which is a BA634 flip-flop (bottom left in the circuit diagram). There is a thread on that thing: https://www.diystompboxes.com/smfforum/index.php?topic=116541.0
To turn the circuit on permanently, find transition Nr 3 from the main to the SW board and cut it. Solder the end of that that goes to the SW board to +9V. Transistion Nr 7 is the nearest access to +9V, probably. Now the circuit should be stuck on "on".

I can confirm this is correct and still maintains all of the functionality of the pedal!

It will work for the DD-2 and "Long-Chip" DD-3!

Thanks, Fancy Lime!

Does the hold mode work right?
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Glad if I could help!
10
Ah, I see. The switching is done with IC9, which is a BA634 flip-flop (bottom left in the circuit diagram). There is a thread on that thing: https://www.diystompboxes.com/smfforum/index.php?topic=116541.0
To turn the circuit on permanently, find transition Nr 3 from the main to the SW board and cut it. Solder the end of that that goes to the SW board to +9V. Transistion Nr 7 is the nearest access to +9V, probably. Now the circuit should be stuck on "on".

I can confirm this is correct and still maintains all of the functionality of the pedal!

It will work for the DD-2 and "Long-Chip" DD-3!

Thanks, Fancy Lime!
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