rebote 2.5 debugging

[Kipper4]

Second time around with this effect this time its my layout based on tonepads with a few mods
all of which have been removed until i can get it working
what it does
delay time pot works
level pot working
repeat pot doesnt i only ever get one repeat no matter where i set the pot
tl072 voltages are all where they should be
subbed the 24ks in the ic2a with 22ks
what the hell is going on here?
cheers fellas

[italianguy63]

Repeats are set by the resistor values and the pot value combined.  Double check the resistor values in the surrounding circuit!

MC

[Kipper4]

Thanks Mark will do, Im all out of time just now.
I have to go to work.

[Kipper4]

my 100kB level pot is only giving me 20k lug 1 to 3

[vigilante397]

Having built approximately a million of these I've seen this problem pretty often. Is this a board you etched yourself or one purchased from Tonepad? If it's one you etched yourself, follow the traces attached to the pot, make sure they are nice and thick and not split anywhere. The most common time I see this is when my toner mask faded on that particular trace and it's either split or not thick enough to pass signal.

If it's a board purchased from Tonepad (which are fantastically high quality, by the way) then you obviously wouldn't be having this problem and should check resistor values. The biggest one aside from the pot that makes a difference is the 15K resistor at the end, so check that to make sure it is 15K, and if possible try dropping it to 10K to see if it makes a difference.

If none of these are helping, it's time to break out the audio probe and poke around. One of my favorite tings about Rebotes is that an audio probe tells you everything you need to know in debugging.

Good luck!

[Kipper4]

My layout on perfboard. I'll check those later. Get off work in 4 hrs.
Thanks whipping boy.
Browsing on a phone blows period.

[italianguy63]

Thanks whipping boy.

LOL... That made my day.   

[vigilante397]

Thanks whipping boy.

That's what I do

[Kipper4]

I did the mark hammer mod but removed it to eliminate it

[nickbungus]

The most common time I see this is when my toner mask faded on that particular trace and it's either split or not thick enough to pass signal.

Very interesting point, would the advice be to add a layer of solder over the trace?  Actually would it be beneficial to do this over all traces?

[vigilante397]

Very interesting point, would the advice be to add a layer of solder over the trace?  Actually would it be beneficial to do this over all traces?

That can sometimes work, but usually when I mess up a trace on an etched board I will solder a clipped resistor lead over it just to be safe. It can be beneficial to do it over all the traces, if for no other reason than to prevent oxidation of the copper.

[Kipper4]

Thanks fellas I fixed it.
I made a boo boo around pt2399 pins 13 and 14 what with all the crossong over and all.
the layouts good and verified. It was my mistake in wiring
what gave it away was probing the pt2399s output buffer
Sausage prize for me.
Time to go back and put the hammer mod back in now
I've never done it before I cant wait to see how it works out I'm putting it on a switch so I can A B it.


subbed the 2k7 for a 2k2 no problems there
subbed the 2x 24k in the output buffer with 22ks
subbed the 27nf with a 30nf
Also Incorperated a madbean super simple tails mod on the pcb should i wish to put another switch in and swop between tails mode and bypass mod (bypass mod bieng the delay is always on)
this is what i did with my last one and it worked out great for dub and reggae studio effect for tails on chosen notes/chords when the momentary footswitch is depressed in tails mode.
I hope that last bit made sense. It did in my head when i wrote it.
Onwards and upwards.

Next project a Rat with Anchovies mod.
edit for those that missed it here you go
http://www.diystompboxes.com/smfforum/index.php?topic=112108.msg1033466#msg1033466

[Kipper4]

Great mod Mr Hammer it sounds more natural.
For the two extra parts its so worth it.
Its a waste of time putting it on a switch I'm just gonna wire it in permanant.
Thank you very much.

[vigilante397]

My favorite mod used to be putting the 15k switch on a DPDT with a 10K on the other side so you can get switchable infinite repeats, but I've decided I like it much better with a 4.7K. The lower resistance means more repeats, and with it that dangerously low it's easy to drive the PT2399 into full on oscillation and glorious noise

[Kipper4]

I like that mod tooNathan. I did it in my first one with the 10k on a switch.
I aint ever been as low as a 4k7 though maybe i'll throw it in just to see while the perf is outside the box.
I guess it wont make the chip latch up.

[vigilante397]

I guess it wont make the chip latch up.

Nope, it will just turn it into a vicious noise making machine It basically becomes a growling pitch generator at that point, it doesn't respond to guitar input anymore, you just control the pitch of it with the Delay pot. Super fun for squealy Rage Against the Machine-type noise solos.

[Kipper4]

I did the infinite mod on a switch with a 8.2k---3.9k-----100nf combination
Splitting between the resistors.
Kinda worked but wasn't really getting the run away delay I got with my first one
Just a heads up you won't get infinite run away repeats if you put the 22nf to ground Mark Hammer mod.
I put that on a switch now to so I have best of both world.