Danelectro true bypassing

[expanoncolin]

I have worked only with bypassing mini pedals, and all but the PB&J have used the same switching board (good move danelectro!).  The switching involves a bit plastic non-latching DPDT, but it is simply being used as an SPDT, which is used to trip a flip flop, which then switches a 4053... being used as a DPDT in this case, to bypass or unbypass the pedal.  The 4013 also provides a signal for the LED's on/off, as the LED is always on the other circuit board.  There are a variety of kludgy methods involving forcing the electronic switching into the non-bypassed state at all times, either by simply relying on the pedal to "turn on" as soon as power is applied, or by jumpering the switch, or by cutting some traces on the flip flop and hardwiring, so that the coontrol for the 4053 switching is always non-bypassed.  I tend to not like those methods... I always feel dirty using them, because you're leaving so much in tact that can be removed!  A whole circuit board, in fact.

Each dano mini (other than the PB&J) has 6 wires from the switching board to the effect board.  Not all of them are used all the time!  This is a sacrifice danelectro had to make when they decided to do one switching board.  The wires, in order starting with the one closest to the input jack, go (color may vary... but I haven't seen it do so)
Send (blue)
9V (green)
Ground (yellow)
No-bypass Send (orange)
Return (red)
LED control (brown)

No-bypass send is essentially a wire that always contains the input signal, regardless of whether the effect is bypassed or not.  It's used in some pedals (just the chicken salad as far as I know) and not in others.  If you look at the effect board and it is not connected to anything, you can just cut that wire.  LED control you can also ignore in any case, because you will be using your 3pdt for the LED on/off.  So that leaves you with a simple set of connections on the effect PCB to connect your 3pdt to... almost.  There one caveat is that on the switching board, all of these are biased to Vref...  (as far as I can tell-the last time I did a TB to a non-PB&J mini was very long ago... but I am about to do another and will report back).  So you will need to do the standard referencing...  100k to V+, 100k to ground, a cap with the negative end to ground and the positive to the junction of the resistors, the junction then connected to two 1meg resistors, each individually connected to .1uF caps, connected to the input and output... after the .1uF cap, you go to the switch.  Sort of a pain... I have not tried ignoring the bias but it might be possible.  It's up to you in the end whether it's easier or not to kludge the bypass.

For the PB&J, it's a bit different... you cannot remove the switching board because the switching is on the same board as the delay chip!  The three boards are switches, effect, and buffers.  There is no real way to get around using the buffer board.  The switches you can get rid of.  My current favorite way to do true bypassing, while retaining the ability to select long or short, is to cut legs 2 and 5 on the tiny SMD 4013, and then make a little jumper between legs 10 and 8.  Then, just do the TB to the jacks on the buffer board.  You can also simply use a DPDT for long/short...  take a look at the schem, you just ahve to cut a trace and switch a leg on the PT2395 between high and low, using the other throw of the switch for the LEDs.  The LED in the PB&J is a 3-leg two color LED, with a common anode (the center lug).  I just use the 3pdt to switch the center lug on and off, wiring two LEDs with their anodes connected and wired to that 3pdt switch's lug, and wiring the cathodes to the PCB.  Either way works dandy.  If you are really good, you'd make a new buffer board-the PB&J has a few very silly things, one of them being that the op amps are powered with 5v of headroom when 9v is available.

Good luck...

-Colin

[expanoncolin]

Inserting a ground-referenced signal had no trouble with the French Toast.  I imagine it all depends on how the input of the thing is biased, this thing uses a biasing cap and a pulldown resistor anyways.

As a note, Danelectro sometimes uses the casing of the pots as jumpers.  Keep this in mind if you are removing pots.

-Colin

[DreamSeller]

Since youve pulled apart a french toast you could probably help me.

How exactly did you TB it. Whats the best way for this pedal, Is there a way of doing it to completely remove the switching board (Im rehousing it anyway so could I just hack the sound board of the switching board and wire everything again without the switching board? Also what exactly is the trim pot controlling cause I liked some of the tinny noises I could get but adjusting it.

Is there anyway to get an up/down sweep switch, And finally did you bend this circuit? I tried and got nothing, Then again it was my first attempt at a bend so I dunno, I just probed around with a 1M resistor.

Thanks

-Dream

Also when I rehouse this thing I was thinking of putting in an LFO on the 9V to the sound board, Is it worth it?

[expanoncolin]

Which circuit are you rehousing?

Whichever one it was, just follow what I said about true bypassing it... you can completely remove the switching board easily.  I don't know what you mean about the sweep swithc if it's the french toast.  You will not get any results hardly ever with a 1M resistor, try 1k.

-Colin

[DreamSeller]

Wow my mistake, I have a french fries.

My Bad

-Dream

[DreamSeller]

So when bypass and removing the switching board I cant just hook up 9V to the V+ wire, I need to add the jargon thats on the switching board too.

-Dream

[expanoncolin]

No, you can just wire straight up, I believe.  You can do a groudn referenced signal without too much trouble.

-Colin

[DreamSeller]

Not really sure what you mean by "Ground Referenced Signal"

-Dream

[expanoncolin]

Signals like the guitar's signal, or just about any old signal, are referenced around some point.  Ground is the most common reference, it's what is generally referred to as 0v.  This means that the guitar's signal oscillates positively and negatively around 0v.  The danelectro switching system converts the guitar signal into a 1/2V referenced signal-so that instead of alternating around 0v, (say from -100mV to 100mV) it alternates around 1/2V or 4.5V (say 4.4V to 4.6V).  But, inserting a ground referenced signal instead worked fine for me.

-Colin

[DreamSeller]

OK so if I just insert the guitar signal straight to the sound board it may not work correctly, If this happens I need to trace the signal on the switching board and see what happens to it before it hits the sound board.

Also would it be worth hooking up and LFO and are there any bends or mods you can think of off the top of your head for really whack sounds? Somting kind of 8-bit sounding would be awesome.

Thanks

-Dream

[expanoncolin]

EDIT-Moved.

[DreamSeller]

Man, I have never seen a 3d printed pedal box.  That is super cool.  How do you have access to that?
-Colin

Uh, Have I given the wrong impression here somewhere?

-Dream

[expanoncolin]

Whoops, that reply is supposed to be in the feedback loop thread.  Let's do some editing...

All right.  You should just see what happens with the normal signal, if it doesn't work we'll go from there.  

-Colin

[danoisefactory]

OK, so now for the award of stupid question, but i want to rehouse my PB&J.

Can i replace the switches with rugged momentary footswitches?
I tried to understand the whole true bypassing bit, but get lost in the information, as wel,l i have no trouble with the effect not being TB. Also i like to switch between the two delay times so when rehoused i still want the old features and working.
Basdically, i just want to put it in a bigger box, çause its to small to be able to control with my feet (and the aren't that big!).

Also question, I read that when i replace the speed pot with a 500k and the repeatpot with a 1M pot, i can get upto 15 sec of delay. Anyone tried that yet? Will i still be able to have the very short delay with a long repeat (sustaining nearly endles, while degrading is one of the best sounds from the PB&J imo)?

[DreamSeller]

I bent my french fries. Cant remember the exact things as it's not in front of me right now but I took a 22k resistor and hook it from ground to two different resistors. one was the resistor between the hi/low switch and the opamp mcdooby and the other was the resistor at the very top of the board between the switch and the pot.

I will post some sound samples at some stage but I get sounds kinda like a synth from one and glitchy sounds from the other and when I adjust the high low switch with the glitch I get a fuzzy distortion sound.

All wired up and in the same box, tight fit in these buggers. Unfortunatly I misjudged the hole so now there are two in the front but meh.