@#$%^&*!!!! rebote!!!!

[pinkjimiphoton]

so my wunnerful little rebote 1 that i love so much crapped out last nite at the gig..

light comes on, just puts out a loud HUMMMMMMMMMMMMMMMMMMMMMMM when engaged. i figured something stupid happened, and took it out of the signal chain to fix it today.

so i opened it up, and i can't find anything wrong with it!!

all the voltages seem right, the regulator is working, yada yada...but all i get is HUMMMMMMMMMMMMMMM

on a battery, it will pass some audio, but no delay.

if i pull the chip, i can still hear a bit of hum, so pretty sure it's not the chip.

there's about 3,000 freakin' caps on this thing...i'm figuring one must have gone down? maybe?

any ideas?

[Derringer]

audio probe it

could still be the chip though because I don't really know what one would sound like without the chip

my instinct though tells me to look for leads that have come unsoldered

[Kesh]

so my wunnerful little rebote 1 that i love so much crapped out last nite at the gig..

light comes on, just puts out a loud HUMMMMMMMMMMMMMMMMMMMMMMM when engaged. i figured something stupid happened, and took it out of the signal chain to fix it today.

so i opened it up, and i can't find anything wrong with it!!

all the voltages seem right, the regulator is working, yada yada...but all i get is HUMMMMMMMMMMMMMMM

on a battery, it will pass some audio, but no delay.

if i pull the chip, i can still hear a bit of hum, so pretty sure it's not the chip.

there's about 3,000 freakin' caps on this thing...i'm figuring one must have gone down? maybe?

any ideas?

you could try checking the voltages on any cap that goes to ground. If they're at zero or close the cap might be bust.

[jsleep]

Make sure to look for the simple things.  Loud hum is often caused by a short to ground in the audio path.  like a input or output jack tip touching against the enclosure, etc.
JD

[pinkjimiphoton]

hi guys,
all great suggestions, thanks.

i've checked out all the caps, well, all the electros... i get 3-4v average on + side, zero on the side connected to ground.

i've used this pedal now for a couple months with zero issues other than when on battery, where it freaked out..i posted video of it.

ok...so anyways, i replaced the regulator and the chip as well,
and...it gets weird.

on a battery, it works perfectly well...i've run it on a wart since i discovered the thing got too weird if the batt got too weak.

but...as soon as i plug it in with any c- normal wall wart, it hums like crazy, and it sounds like the chip is overloading...the repeats runaway out of control, and the delay time goes nuts as well...it starts feeding back and doesn't stop, accompanied by this obscene hum. unplug the wart, suddenly it's fine as soon as the overloaded signal fades.

i tried adding a power jack filter to it to see if it would help, a 1n4001 with cathode to + and a 100uf cap, makes absolutely no difference.

i'm almost wondering if maybe the power supply jack has failed? i mean there's the b+ coming in from the jack , the bat + is on the switch, the ground connects to the center lug.

after that, there's nothing between the jack and the regulator pretty much other than a 47uf cap.

when not plugged in, it works...when it is plugged in, it messes up. to me, it's gotta be the jack is failed or shorted internally?

i mean, why else would it fail as soon as i plug it in? any ideas? voltages to the reg/chip/fet don't change significantly ,,,the batt's getting weak, the power supply is reading 9.47 v or so, so it goes up very little with the reg..maybe to about 5.9v.

so it's just not making sense...i'm wondering if maybe someone stepped on the power jack at the gig and broke it...

stumped!! why would it work with a battery fine, but not a wart?

i'm gonna try

[chromesphere]

Hey Jimi. Although i cant recall exactly how the mechanical side of the DC jack works, i was thinking maybe +9v wallwart and +9v battery have somehow come into contact, providing +18v to the circuit (if thats possible).  Does the pedal work with only the dc jack plugged (no battery)?  Either that or the regulator is somehow not liking the current draw from the wallwart?  This is a strange one lol..
Paul

[Govmnt_Lacky]

Unplug the battery..... Insert wall wart..... Retest  

If you still get the nastiness then it can't be the DC jack.

[oldschoolanalog]

>...i'm wondering if maybe someone stepped on the power jack at the gig and broke it...<
Sounds more than plausible. Especially after hearing about some of the places you gig at.
Was the "Melissa" psycho there? (Just joking   )
Seriously; disconnect the wires to the jack and clip on the PS. Betcha' it works.
Or maybe the plug on the wart got damaged? Try a different wart?

[pinkjimiphoton]

ok...so i disconnected the old jack completely.

use roach clips on wires (hah hah, i mean jumper cables) to connect a new jack. plug in wart.

same freekin' problem!!

tried a boss regulated adaptor, the one spot i use live, my back up one spot...all work fine on every other freekin' pedal.

it's not the battery, if i disconnect the battery, makes no difference. as soon as i unplug the wart it's dead. hook up the battery, works fine.

why would a cct that works fine on a battery suddenly stop working on a wall wart, wtf?? it SOUNDS like dc is getting into the audio path...
normally, that would be a bad blocking cap, or a bad rectifier.. well...there's no rectifier, so it's gotta be a cap, right?

but if it IS a cap,  why is it ok on a battery, and why would it be fine til last night?

this is the cct i'm using and the layout:
http://www.tonepad.com/project.asp?id=17



i mean...where the hell could it have messed up? stumped...  footswitch failure maybe?

[Mark Hammer]

Um, is that one of the boards I sent you?

If so, be VERY sure to go over the thing and compare it to the PCB mask, because there might be a bridge or a gap somewhere that neither of us have noted...yet.

[pinkjimiphoton]

hi mark,
yah, it's the rebote board you sent me. i love, no, i LOVE this thing...i use it constantly live, i love the simplicity of it. i use it mostly for ambience during solos and heavy parts, and it's nice to be able to adjust the repeats/mix with the one knob..it's VERY sandal-friendly in that respect.
i've got a guitar pcb version (the d'lay) that will work if i have to, but it sounds different from the two knob (barry's project has time, mix, and repeats...tho, for the record-at least on my build- it's one of THE quietest designs i've tried with a 2399..the noise is minimal even with the delay time pegged)...
the earlier one sounds a lot more echoplex-ish, for lack of a better word. (i've got two plex's, but i like this better and it's wayyyyy smaller).

but i'm getting off target here...
i don't think it's a trace or bridge, i've been using this thing now live for about 3 months with no problem other than when the battery gets too low, which makes it sound very weird:

i mean, i can USE a battery with it live, it's just a bitch if it dies in the middle of a gig or a song, cuz the chip locks up and it oscillates like an echo chamber full of banshees.

this is more of some weird oscillation almost....i think it's in the feedback path somehow, but i can't seem to find it.

and why the hell would it work fine on a battery, and not on the ac? it makes no sense, i mean, the circuit can't tell what the heck is powering it!!!   

[haveyouseenhim]

Voltage starve on a delay?    hmmm....    Pretty cool. Sounds like an evil ice cream truck 

[pinkjimiphoton]

how the hell do you debug something that's working, when the only damn variable is a jack and a wall wart? i mean..the battery even hooks onto the jack, so.....

[oldschoolanalog]

how the hell do you debug something that's working, when the only damn variable is a jack and a wall wart? i mean..the battery even hooks onto the jack, so.....

Put it into non-working condition (PS connected). Take V's. Then put it into working condition (battery connected). Take V's. Then compare the 2 sets for anomalies.
Really strange problem you have there. 

[pinkjimiphoton]

i tried that, dave, but all that changes is the b+ goes up about a volt, the regulator that feeds the circuit doesn't change, so all the voltages...other than at the power jack...stay the same.

stumped, dude..really weird.

it sounds like dc is getting in somewhere it shouldn't be, but where?

i can take it all apart again, a piece at a time, but i don't think it's gonna matter...it works fine on a batt, where as before, batts died real quick and the wart was fine. 

[oldschoolanalog]

This is truly an o'scope moment. That way you can see if/where any DC is mucking things up. Have access to one?
Have you clipped the wart onto the battery snap terminals?

[pinkjimiphoton]

great minds, dave...

yes, i did try doing it direct...same deal.

i DO have an oscope, i just started a thread asking how to use it.

like...feed audio into the input, and work my way back from the input jack with the scope probe i'm imagining?

[pappasmurfsharem]

Don't know if this will make a difference but, what voltage does your battery output.  Maybe try a pot in line with your dc jack and see if lowering the voltage slightly to a similar amount the battery outputs Helps.

[pinkjimiphoton]

hey papa, what the heck, in for a dollar...

[pappasmurfsharem]

hey papa, what the heck, in for a dollar...

I mean I'm a complete noob, but maybe the pt2399 has become "voltage picky"... Who knows it seems like you have basically eliminated any wiring mishaps.

You did say it works dandy with the battery right? Iron on my phone and the chrome browser on Android glitches out like crazy so reading posts gets to be a hassle. Besides I'm sure you have a spare pot housing around somewhere considering your pedal collection. Just "roach clip" That biznatch on there and see what happens.