CHASM REVERB

[deadastronaut]

pre delay?..

[mmlee]

Pre-delay is usually found on studio reverbs.  It's basically the time between the dry signal and the first reflection, usually measured in ms I.E. how long it takes before the wet signal starts.

[deadastronaut]

yep i get that, not sure how it applies to these bricks though...

[gtangas]

hi again!

so i check the electros and all are 10uf

as i said the distorted signal fades after as few seconds.... can i swap those for another values?

[deadastronaut]

^ are your electrolytic caps  the right way around?...

[gtangas]

G morning DA

Yess the caps are ok and for a weeks everything worked ok. The thing start to happen a days ago...

I have to disassemble it and check the transistors and some values.... Not in the mood for it but... AAAAAAAA

[deadastronaut]

morning..

that's a shame, i hope you can identify the problem..

bad mosfet maybe.

[gtangas]

Maybe... I had J201 at the beginning of the build... The orders from tayda are taking almost a month to arrive to Portugal... But it was the only thing that I swap...

[gtangas]

solved.... bad tranny!! now its running with two J201 and everything ok again!

[deadastronaut]

Cool, glad you got it sorted...

[gtangas]

Yeaaaa

[loylo]

when mix is at zero fully left...no reverb at all, as it should be.

@1:50

http://www.youtube.com/user/100roberthenry?feature=mhum

I definitively have a problem with the mix pot. 
There is some bit of reverb when the sound is supposed to be dry. It is barely audible when I'm playing at home, but it is noticeable, even more when playing in a band context.
The pot is fine, the mix control acts the same with another pot. And there is no problem such as a soldered jump or a bad component's value.
Whereas in your video, your mix control seems to sound as it is supposed to... 

as for time 'limiting' i think thats just down to the brick itself not allowing that. 2:85s..

Your are right, the decay could'nt be adjusted, it is preset in the brick (while the BTDR-3 let us dial it). Same for the predelay.
I am close to try to dismantle the brick (like this: http://ada.graudal.dk/bdtr2/bdtr2_top.JPG) and remove some CMS resistor to make them adjustable and have those control, thanks to the russian guys who traced the brick. http://www.freestompboxes.org/viewtopic.php?f=20&t=23706&p=232607&hilit=btdr#p232607
But it is risky! 

Otherwise, I've came by a version of the Tenebrion reverb modded with a "short/long" decay switch.
http://guitar-gear.ru/forum/index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=29936
I don't know if changing from a 100K  to a 1K "verb" pot make the decay shorter as this schematic suggests it.

I should try to add a 100K pot wired as a variable resistor with a 1K fixed resistor at the tail, acting the same as the "verb" pot always at the max setting, as the reverb level is kinda controled by the mix pot.

[deadastronaut]

mad seeing inside the brick...

loylo:  i have pm'd you...

[chi_boy]

So I realize the schematic is a touchy subject because of the Brazilian Incident, but is there an updated schemo to be had?  I did find the V1.6 in the other thread, but a lot seems to have transpired since that version.  This thing is just too cool not to build.

Thanks,
George

[pinkjimiphoton]

mike/haveyouseenhim burned me a board... populated tonite, wire it tomorrow... wish me luck!!

hey is there a quick easy way to test 5457's? i have a few but i am concerned one may be damaged.. they're slopping around the bottom of my junk drawer.

could i sub 2n5952's ina pinch?

[pinkjimiphoton]

bugger, if i mess with it i get it to switch on, very hissy and no verb, but taking voltage measurements sometimes i can hear the reverb for a split second.

gotta try and debug some. gotta be something stupid!!!

[haveyouseenhim]

gotta try and debug some. gotta be something stupid!!!

Yea. Like letting some stupid Alabamian etch boards for you.   

[pinkjimiphoton]

betting it's something stupid even for ME.

for a dumb alabamian, you had the proper number of holes in the right spots, so i think it's good old yankee lack of ingenuity. 

[haveyouseenhim]

you had the proper number of holes in the right spots

That was pure luck. I just shot it with some birdshot 

[pinkjimiphoton]

ok.... found some bridges and some cold solder... got the thing kinda running.
i baked one chip and one 7805 so far.

got clean signal... and loud... with the volume all the way down. if i turn it up whatsoever, the brick starts motorboating like crazy, sounds like a damn airplane.
the modulation is working. i can hear it on or off. so THAT's good...

any ideas as to where to look to find the motorboating problem? i had a hell of a hum, i thought it may have been from having the 1u cap backwards... i had oriented it with + to the right originally, tried it the other way and lost the hum.

i've tried subbing the 2n5457's, no change at all, so assuming they are working. i haven't tried the 2n7000, do you think that may be the culprit?

funny... yesterday i had reverb. today, i have an airplane synthesizer.

help!!! please