How to "Sshhhut" up a PT2399 once and for all!

[~arph]

R.G tried that I believe

[Mugshot]

R.G tried that I believe

did he get a response? im curious as well. once the manufacturer sheds light on some of the mysteries of this IC, im imagining a slew of other projects from the creative guys of DIYSB 

[~arph]

Come to think of it, I believe I read that he called princeton to see if a version with a longer delay time would be availble. Don't think it was about the pt2399 specs.

[Derringer]

so how does this look for altering Tonepad's Rebote 2.5 pcb?
pin 4 would still be connected to the delay pot lug-1




and I do see that some folks feel that the pin3/pin4 connection/disconnection doesn't seem to make much of a difference
but I just had an urge to play with the pcb layout anyway ... if only to get the decoupling between pins 1 and 3 closer
as per Merlin's write-up of the PT2399

thanks!

[mwynwood]

I'm not sure if this is anywhere near correct... but are these the changes required on the Vero from Sabrotone.

Original Vero:


My dodgy attempt at making the changes:


I think I could be *way* out, but I'm new at this 
Thanks guys!

[Derringer]

so how does this look for altering Tonepad's Rebote 2.5 pcb?
pin 4 would still be connected to the delay pot lug-1




and I do see that some folks feel that the pin3/pin4 connection/disconnection doesn't seem to make much of a difference
but I just had an urge to play with the pcb layout anyway ... if only to get the decoupling between pins 1 and 3 closer
as per Merlin's write-up of the PT2399

thanks!

just to follow up, I could not get the Rebote 2.5 to work in the manner I indicated above
it would only work in the stock configuration .. and it isn't noisy enough stock to bother me anyway

I tried it on the breadboard first (thankfully) and found that if I powered the circuit up in the stock configuration AND THEN disconnected pulled pin-4 from GND, it would work.
But if I powered the circuit up without pin-4 connected to GND, it would not give me delay.

[nordine]

so how does this look for altering Tonepad's Rebote 2.5 pcb?
pin 4 would still be connected to the delay pot lug-1




and I do see that some folks feel that the pin3/pin4 connection/disconnection doesn't seem to make much of a difference
but I just had an urge to play with the pcb layout anyway ... if only to get the decoupling between pins 1 and 3 closer
as per Merlin's write-up of the PT2399

thanks!

just to follow up, I could not get the Rebote 2.5 to work in the manner I indicated above
it would only work in the stock configuration .. and it isn't noisy enough stock to bother me anyway

I tried it on the breadboard first (thankfully) and found that if I powered the circuit up in the stock configuration AND THEN disconnected pulled pin-4 from GND, it would work.
But if I powered the circuit up without pin-4 connected to GND, it would not give me delay.

i had this very problem, has been found what causes it? are there some versions of the pt2399 that respond well to this trick and some that dont? .....ive found it to work once in like 30 attempts... when it doesnt, theres no delay, and the 7805 heatens like crazy... when it works, it indeed cuts all digital crackling from repeats, and that motorboating sound in long repeats that i hate

[ECistheBest]

i couldnt get the PT2399 to give me delay with the digital ground lifted. dont know why, but the chip got really hot and the output i wasnt getting any delay. buffered output was working though of course.

[chi_boy]

It's seems strange that it wouldn't work considering that the Deep Blue Delay is wired just that way. 

[Harold]

When looking at the (old) PT-80 schematic and layout, it seems that the "Sshhhut mod" would be:
1. Remove the jumper from pin 4 to ground
2. Move the 47uF cap between pin 2 and 3 to pin 2 and ground

Is that correct?

Edit: Pin 3 = GND, so the cap is already between pin 2 and GND That only leaves the removal of the jumper?

Schematic: http://www.generalguitargadgets.com/diagrams/pt80schem.pdf

[Harold]

Tried it, but it didn't work. The only way to get the delay chip started was to jumper in 4. After the delays were working, I could remove the jumper, but that didn't fix anything.