Problem PCB Pauper

[coccoslash]

Hi everyone.
I have a problem on the Pauper. I think I burned the pads where the diodes are soldered (I did various tests changing from Ba283s to 4148s..and I did the damage). Practically the on/off/on selector no longer works. Acting on the switch, the pedal always remains only in the OD position (I think ... or maybe DIST).
Is there a way to bypass the PCB and attach the diodes directly to the switch? Or other solutions?

Thanks so much

 

[Mcknib]

They look ok, datasheet says 100mv so given meter accuracy and test conditions in the datasheet they're ok

What's you're VREF voltage

 

[coccoslash]

They look ok, datasheet says 100mv so given meter accuracy and test conditions in the datasheet they're ok

What's you're VREF voltage

How can I measure it?

 

[Mcknib]

Set your meter to 20 vdc black probe to ground red to the VREF switch lug

 

[Mcknib]

The forward voltage for an MA856 is actually 1v in the datasheet, I can't read datasheets right!

 

[coccoslash]

The forward voltage for an MA856 is actually 1v in the datasheet, I can't read datasheets right!

I use 4148s

It measures 4,5v

 

[Mcknib]

They should be around 0.7 forward voltage

Anyway spoke to Mr Ppcb again to double check those traces are correct pcb images are not always accurate but they're confirmed ok

So the only thing I can think of is those diodes aren't conducting properly for some reason VREF should be half the power supply

As he pointed out you are getting audio in that position just not distorted

 

[coccoslash]

They should be around 0.7 forward voltage

Anyway spoke to Mr Ppcb again to double check those traces are correct pcb images are not always accurate but they're confirmed ok

So the only thing I can think of is those diodes aren't conducting properly for some reason VREF should be half the power supply

As he pointed out you are getting audio in that position just not distorted

I mean, 4,5v is the VREF voltage.

 

[Mcknib]

I use 4148s

It measures 4,5v

That's correct you've definitely got gain turned up?

 

[coccoslash]

That's correct you've definitely got gain turned up?

I've always (2x) boost mode (middle and down)..I see no solutions

 

[Mcknib]

There's always a solution! mind you it escapes me for the moment

Look at your positives, you never trashed the pcb, you've hopefully learnt something, you had nothing on your SW, now got 2 and 3 will definitely be the magic number

It'll be something simple and easily overlooked

Lets see a picture of it now both sides

I'll see if I can see anything when I finish work best actually do a bit...work that is!

 

[coccoslash]

There's always a solution! mind you it escapes me for the moment

Look at your positives, you never trashed the pcb, you've hopefully learnt something, you had nothing on your SW, now got 2 and 3 will definitely be the magic number

It'll be something simple and easily overlooked

Lets see a picture of it now both sides

I'll see if I can see anything when I finish work best actually do a bit...work that is!

Thanks Mate! You're right..
I attach more photos

 

[Mcknib]

Had a look you've still got solder joints that are like blobs of solder those could be dry inside using solder as a jumper will work but it's not advisable, change those for small jumpers like cut off component legs put a little solder on them and some on the part you're joining them to and it'll be easier to put them in place

Does D3 have a crack across it

 

[coccoslash]

Had a look you've still got solder joints that are like blobs of solder those could be dry inside using solder as a jumper will work but it's not advisable, change those for small jumpers like cut off component legs put a little solder on them and some on the part you're joining them to and it'll be easier to put them in place

Does D3 have a crack across it

View attachment 4986View attachment 4987

Ok thanks. I'll try cut off component legs.
D3 seems ok..but I can change it (I've several 4148)

 

[coccoslash]

So .. I'm going to throw it out the window
Blobs removed and I use component legs for the joints.
Changed all diodes (used BA283s..maybe I prefer 4148s ), changed switch with new one...nothing changed.
Still (1x) OD mode and (2x) Boost modes
I am tempted to change the switch to an on/on type and close the issue (and use only 2 modes)

 

[Mcknib]

Don't change anything till you know it's broken

If it's working ie you get audio through the switch the fault must lie elsewhere go over your build and visually check for cold solder joints and reflow any dull or blobby looking joints

It will be something simple a cold solder joint, bridge etc check R15, R9 and C14 all have good joints and take the voltage at pin 7 IC1.2 which should be good if the other positions work

And to make 100% sure what working position it's in - od or distortion, when you've got it in that working position continuity check which switch lugs are connected and what components they connect to

The switch position it's in, in the schematic is distortion - out the op amp then down from the 1Ks through the diodes to VREF like a rat except 4 diodes so check everything from pin 7 down to VREF is all good

Perhaps we've been concentrating on the switch and diodes too much

 

[coccoslash]

Don't change anything till you know it's broken

If it's working ie you get audio through the switch the fault must lie elsewhere go over your build and visually check for cold solder joints and reflow any dull or blobby looking joints

It will be something simple a cold solder joint, bridge etc check R15, R9 and C14 all have good joints and take the voltage at pin 7 IC1.2 which should be good if the other positions work

And to make 100% sure what working position it's in - od or distortion, when you've got it in that working position continuity check which switch lugs are connected and what components they connect to

The switch position it's in, in the schematic is distortion - out the op amp then down from the 1Ks through the diodes to VREF like a rat except 4 diodes so check everything from pin 7 down to VREF is all good

Perhaps we've been concentrating on the switch and diodes too much

Thanks. Unfortunately I think I have permanently burned everything. Even the led. The pedal doesn't work anymore completely.
Thanks but I decided to throw the PCB away, buy a new pcb and do it again when I feel like it again.
I thank you for your support. I hope to hear from you.

Edit: Pauper is out of stock...great

 

[Mcknib]

Never mind at least you learned a few things...hopefully!

It's a shame you removed the switch that in itself isn't easy to do

Although it's difficult when you're frustrated you've just got to stay calm and not remove anything until you know it's faulty

That's a shame you were almost there!

I suppose patience is a virtue............................That nobody wants!

 

[zgrav]

when you order another board, order more than one kind of pedal you want to build and try to go ahead and order the parts for both boards. it saves money on shipping costs, and it is easier to set a problem board aside to clear your head if you have another pedal you can start working on. and when you order parts for a board like resistors, caps, jacks and switches, go ahead and order a few extra to start building an inventory. no need to rush, but you will see savings on shipping and get a head start on future builds.