SOLVED DUOCAST weird issue

[droneshotfpv]

I MAY know the answer to this already, but wanted to ask the more qualified peeps than myself. I just built my DUOCAST, sounds amazing in 9v mode.
I made sure ALL my caps (as I usually use anyway) were rated 50v+ before using them, aside of one "special" order one I needed to order to complete the build, which was the sole 330uf cap, and it's 35v, which should be plenty.
Anyway, plugging along, this thing, as I said, sound marvelous until I switch to the 27v mode.. When engaged, it makes sound, but quickly fades out like a fuzz being gated to brink of extinction. Literally goes quiet, but sounds as if, and this is the BEST way to describe it, the sound is what I could compare to a capacitor being full of energy, and then depleted as the voltage leaves the unit...
Fiddling with the switch, I eventually got it to come on, and stay on in that mode (27v) but switching back to 9v mode, it works perfect EVERY time, and then back to 27v, same thing all over again.
I assume I could POSSIBLY have a bad switch, which is gonna suck to swap, but that's an easy place to start, unless anyone could think of different?
Another weird thing I noticed, I am OCD when it comes to checking values / voltages before firing up any new pedal. I put my meter on the this one in 9v mode, checked the voltage at the switch (among other areas) and got 9v on the 9v switch side, but when flipping to 27v and testing those prongs, it started at 37v, and drained down slowly in the teens... I flipped back to 9v, measured, solid, 27v, trickled back down from high 30's again...
So, does this prove the switch is a POS and I need to yank it and try a new one?
Thanks in advance my pedal crazy brothers and sisters!

***EDIT***
Correction, The "drain" I noticed was not when switching the switch TO the 27v side, but rather I tested again and noticed it was when switch to the 9v side... I dunno, this has me baffled lol Help me Obe One, you're my only hope

 

[droneshotfpv]

Ok, so more troubleshooting. Testing that SPDT switch, I noticed that when it works properly, the CENTER post shows whatever voltage is selected, as it should, but when it fails on the 27v side, the center pin fades from spiked voltage, down to 0.8v, and holds. Flippity Floppy of the switch, and eventually center will read properly, at 25.78v or whatever, and hold, and the pedal is perfect.
So I am sticking with "bad switch" thoughts, would ya'll agree with this sentiment?
Love you long time

 

[Mcknib]

Stick some pics of the pcb up it could be a few things, faulty power supply, incorrect value or orientation, poor solder joint etc first thought is it sounds like a cap possibly shorting and pulling the voltage down

Continuity check your switch connections as you'll know the middle common lug should connect to top lug in one position and bottom the other position make sure middle only connects to top or bottom ie one or the other and not both at the same time

When flicked to the top middle and bottom lugs should have continuity

Flicked to the bottom middle and top

Opposite to what you'd expect

Visually check for solder bridges especially around the electrolytics in the power section bottom of the schematic

Check voltages prior to the switch, for the 9v side check D100 cathode and 9v switch lug

27v check D4 cathode and 27v switch lug

You're basically trying to find out where it starts draining if you don't see anything else obvious, so as you're taking voltages wait to see if it drains if it does drain move to the preceding component

Where did you get your LT1054 and is the switch an on / on SPDT

 

[droneshotfpv]

Stick some pics of the pcb up it could be a few things, faulty power supply, incorrect value or orientation, poor solder joint etc first thought is it sounds like a cap possibly shorting and pulling the voltage down

Continuity check your switch connections as you'll know the middle common lug should connect to top lug in one position and bottom the other position make sure middle only connects to top or bottom ie one or the other and not both at the same time

When flicked to the top middle and bottom lugs should have continuity

Flicked to the bottom middle and top

Opposite to what you'd expect

Visually check for solder bridges especially around the electrolytics in the power section bottom of the schematic

Check voltages prior to the switch, for the 9v side check D100 cathode and 9v switch lug

27v check D4 cathode and 27v switch lug

You're basically trying to find out where it starts draining if you don't see anything else obvious, so as you're taking voltages wait to see if it drains if it does drain move to the preceding component

Where did you get your LT1054 and is the switch an on / on SPDT

The LT1054, TY-141P came from Mouser. Actually, most everything came from MOUSER aside of a couple resistors. After every build I go through and reflow all solder points (sometimes when I snip, I snip low and cut solder itself), verify no bridges on both top and bottom points of each component with a magnifying glass (I am 200% OCD and anal about that stuff haha), and I just verified again, no bridges or connections that shouldn't be. I will run those tests you mentioned and report my results.

 

[droneshotfpv]

OK, so everything checks out, the 3PDT switches weren't ever an issue though, only switching from 9v to 27v. IN the test, 9v read 8.97 or whatever on d100, and around same on center SPDT lug. Swapped to 27v mode, drained to zero, but D4 read 26.78v steady. After flipping the SPDT switch back and forth twice, center lug on SPDT switch read 26.78v as did D4, and the pedal sounded great.
The ENTIRE time though, 9v side sounded flawless and like any other demo I have heard, and when the 27v quit draining, it sounded perfect as well. I am going to swap that switch and try again, it has a weird sound to it, and it has a hesitation to it that requires some force.. this wouldn't be the first of these Amazon SPDT switches that were bad on me.. I built a Hyrdra, only to discover 2 of the SPDT's were bad and separated.. I hate de-soldering switches! lol

 

[Mcknib]

Yeah sounds like your switch If all's good after the power supply and up to the switch not something I've come across so it'll be interesting to see if that is indeed the problem

I'd just double check components after the switch as well from R13 including everything up to the voltage divider R2 and 3

 

[droneshotfpv]

I totally appreciate all your input, one of the MANY reasons I love this place!

So, my initial gut feeling was that switch, based on how it felt, and how it was acting. I was hoping to get out of swapping out out, because as I mentioned, switches are the WORST , for me anyway, at removing and replacing, but I did it anyway. It was actually pretty easy this time around! lol
The result was, the problem is now resolved, and it works perfectly. I should have known these cheap Chinese Amazon switches were the fault, but I was hoping it wasn't.. hahaha
Again, many thanks for all the advice!

 

[Mcknib]

Glad you got it fixed

I wondered why you'd mentioned 3PDTs but I see it now, shoulda been clearer and said continuity check your voltage switch connections

If you checked every switch let me know and I'll give myself a well deserved slap

 

[droneshotfpv]

Glad you got it fixed

I wondered why you'd mentioned 3PDTs but I see it now, shoulda been clearer and said continuity check your voltage switch connections

If you checked every switch let me know and I'll give myself a well deserved slap

All good, I sometimes read too literally as well. Haha