Disaster Transport Jr Tails Version

Started by HighSolstice, November 08, 2019, 02:59:01 PM

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HighSolstice

I took a break from working on this build for a bit and knocked out an EQD Acapulco Gold and a Switchable 9v/18v power box with sag controls.  Due to my efforts here, those took me no time at all to complete and worked without a hitch.  I'm still not sure why I can get the oscillations going but my guitar signal has no delay on it.  I received those sockets just yesterday so I might try to remove the TL072 and replace it with a new socketed one.

HighSolstice

I've socketed the TL072 and tried a few of them and got the same readings so I'm back to looking at the surrounding components, still puzzled by this one.

duck_arse

well we've turned the page now, so we've forgotten everything you told us. and you've made changes. so, new photos of your board please, and a new round of voltage measures. please. perhaps also restate the current problem, no guitar? no delay?
You hold the small basket while I strain the gnat.

HighSolstice

https://www.dropbox.com/sh/7jgt7fmpa2wxef6/AABKjvxBM4P4Jto8xbu9OmUza?dl=0

Base Reading: 9.17V

TL072:
1 - 4.41V
2 - 4.41V
3 - 3.62V
4 - 0V
5 - 4.39V
6 - 4.21V
7 - 7.58V
8 - 8.88V

PT2399:
1 - 4.89V
2 - 2.40V
3 - 0V
4 - 0V
5 - 3.97V
6 - 2.40V
7 - 3.44V
8 - 3.48V
9 - 2.41V
10 - 2.40V
11 - 2.41V
12 - 2.41V
13 - 2.39V
14 - 2.38V
15 - 2.40V
16 - 2.40V

Here are some updated photos and readings.  Currently I can hear my dry signal through the pedal whether the footswitch is engaged or not.  The delay can be driven into oscillation independently of your clean signal by turning the pots and this is also heard whether the effect is on or off.  The only obvious effect turning it off seems to have is turning the led on/off.  I fried a bit of the track while I was was moving that link so it's been moved two slots to the right as can be seen in the photos, shouldn't be a problem based on the layout.  I've shown the switch and wires attached to the board in case any of that seems problematic as well.  This has me thinking I should build a test box to make this simpler in the future.

duck_arse

pin 7 of the TL072 should be about 4V3, yours is way high. find where the wrong connection is thereabouts.
You hold the small basket while I strain the gnat.

HighSolstice

I found the problem, I had also burned the track off a bit where that red arrow is pointing.  I added a link between the green dots and now the voltage on Pin 7 is measuring 4.48V but I am still experiencing the same results when I tested it out.



duck_arse

well that's some progress. I tried to understand the description of the "tails" but I'm afraid it makes little to no sense to me without a real live circuit diagram. perhaps - if you un-tails your build back to the standard version, it will dis/prove the basic build, maybe point to the tails-ing.
You hold the small basket while I strain the gnat.

HighSolstice

#27
I tried it again yesterday and I actually heard delay coming from my guitar but it still doesn't seem to behave exactly as intended.  If I get the delay into self-oscillation it takes a while tweaking the knobs back into a sweet spot before I can get the delay sound to come back on my guitar.  I'm not sure what might cause this.