Tonepad DS-1 Not making any sound :-( Bypass works.. pic included

[Hav]

Hey guys

Built the DS1 today and not getting any output when engaged. Got sound from the bypass but just nothing from when engaged.

When it is engaged, gain on full whack I can definitely hear louder hiss, and the tone and volume seem to be doing things but there is just no sound...

IC voltages look like this:

battery: 9.03v

8.45     9.03
8.49     8.10
8.57     8.48
8.92     8.47

Q1

E
8.88          6.10             9.03

Q2

E
8.98           8.23            8.95

Q3

E
8.84           4.42            9.03

Im using a DPDT 'wiring 1' from tonepad just for testing purposes as its easy to wire. will put in the led later.

Diodes are 1n4148 (original 1n914)
Transistors are TL072

Tonepad project: http://tonepad.com/getFile.asp?id=78
Tonepad wiring http://tonepad.com/getFile.asp?id=76

Please help, really want this one to work!



Thanks :-)

[GibsonGM]

WHOA your voltages are far too high!  Something is wrong  - could you have made a 'solder bridge' between adjacent pins, or components??   Look at where the power goes into the board - everything ok there?  Check pin 4 of the IC - ground (battery "-") and that pin should have continuity, as anywhere else that is grounded - you should NOT have ~9V there, so that's indicating a short somewhere....

Ai ai ai ai aeeeee!   Go back thru the solder joints with (literally) a magnifying glass.   If you can, post a pic of the BACK of the board, too.   Your transistor voltages are way off, too, so the problem seems "systemic" and not limited to just the IC.

BTW, did you mean the IC is a TL072?  What are your transistors?

The 4148's are direct subs for 914's, no worry there. 

Typically, if you can find the short(s) and correct them, you're probably ok.  Might have toasted the IC, Q's or what have you, but we'll deal with that at the proper time    These mistakes are the most common, so don't sweat it.

[bluebunny]

. . . post a pic of the BACK of the board, too.

And please get it the right way round!    The picture you posted of the topside is a reflection! 

[Hav]

Ah thanks for the replies guys will update pics, on my phone ATM can't get onto tonepad to check Transistors but it's the ones that they asked - 2n5088 or something like that. Sorry - IC is TL072. I did find one solder bridge and have removed it but I believe I've already blown IC. It's odd I do remember having the values almost at half those and 0 at pin 4 but then I tested again and those above are what showed. Will do a proper search again for bridges and report back. Will the transistors have gone too? Can I use a 4558 as I'm now out of TL072?

[duck_arse]

look what you've done to gibson .....

flip the image, remove the IC, measure the voltages again. and please tell the Vbias (or what it might be called this instance) volts.

this reminds me of the time the circuit had no earth connection or something, and the dmm was just floating all the measures to ~9V. who else remembers that one?

[GibsonGM]

look what you've done to gibson .....

flip the image, remove the IC, measure the voltages again. and please tell the Vbias (or what it might be called this instance) volts.

this reminds me of the time the circuit had no earth connection or something, and the dmm was just floating all the measures to ~9V. who else remembers that one?

I'm ok now, Duck!

You may have ruined the transistors, hard to say.    Remove them too, please, and measure all voltages on all pins for them and the IC.  And like Duck suggests, find the Vbias and read that too, ok?      Black probe on "-" of battery, use the red to measure - sorry if you already know that.

A 4558 can sub in for the 72, yup, but wasn't in the original so eventually you'll stick a new 072 there.    You should try to get a bunch of stuff for your parts bin, like 10-20  2N5088's, and such.    If you have a decent DMM, we can tell you if the transistors are ok - does yours have a 'diode function'?

[Hav]

Hey guys, sorry for delayed reply!

So as per requests:

Image flipped correctly above.

Found only 1 short, now cleared.

Removed all Transistors and IC, put negative to ''-'' on battery and ''+'' on relevant points:


Battery: 9v

IC

0         9
0         0 (starts at 4ish then rapidly reduces)
8.6      0
8.9      0

Q1

E
8.8    6     9

Q2
E
8.9    8.1    8.9

Q3
E
8.8     4.4    9

Vbs

almost all 8.9v, think 1 was 8.8

I have a DMM, it has a 'diode' image on it, but not too sure how to use this to test transistors... it doesn't have any audio beep feature however.

[Hav]

Oh, tried another TL072 with the same transistors, and am getting the same voltages. probably just blew another one :-(

Spent last hour triple checking solders etc and cant see any other bridges :-(

[bluebunny]

IC

0         9
0         0 (starts at 4ish then rapidly reduces)
8.6      0
8.9      0

You have (almost) 9V on pin 4.  This should be zero.  You still got a short somewhere?  Is the battery warm?  Can you do us a photo of the underside of the board?

[Hav]

The battery is ok, tested in other circuits and its good. I have taken the best pics i could here, might need to use a better camera (using phone atm) and some propert lighting, but hopefully this will help...

Just to confirm, where it says 'empty' on tonepad's site, it means just literally leave them empty, not place jumpers or anything in place?

also you will see from the soldering, im still learning!

http://havsingh.com/Guitar/DS1/DS1%20Back%202.jpg
http://havsingh.com/Guitar/DS1/DS1%20Back.jpg

Thanks!!!

[GibsonGM]

Way to know if you have a nice-size short is to plug the battery in, then measure voltage across it...if it starts dropping more than a tad, you know you're shorted.  Remove batt. or it will die 

Ya, empty means empty, no jumper.   That voltage on pin4 really says power supply short...your solder may be ok, but you have to be sure all your wiring goes to the right places!!    If it's wired correctly, it WILL work! 

[Hav]

Battery doesn't dip when plugged in :-( quite solid at 9v...

I will go over the entire layout for the second time, hopefully i'm just missing something, just can't see it! i'm quite certain there are no more shorts, but again, could also be missing something so obvious, maybe someone here will pick it up..

Thanks for the help so far!

[Hav]

making me think ive used the wrong dpdt wiring diagram. is there a 'standard' diagram people use?

[bluebunny]

I habitually use #3 or #5 from the Tonepad wiring doc (in your post), depending on whether I'm using a Millennium-2 or a 3PDT.  Works like a dream.

[bluebunny]

Have you tried checking continuity at various points on the board?  Set your meter accordingly, put one probe on the battery clip "-" (without the battery connected) and check all points on the board (and on your jacks) that are supposed to be "ground" (green on the tonepad diagram).  Now do something similar with battery clip "+" and all the 9V points (red on the tonepad diagram).  Now (or first!) check that there's NO continuity from the battery clip - to +.  Also: with the battery connected, the pink V_REF trace should be 4.5V.

[duck_arse]

there is 2 x 6k8 resistors at the top o' the board. what values do you have fitted there? and that 68nF at C2, not 470nF?

[Hav]

there is 2 x 6k8 resistors at the top o' the board. what values do you have fitted there? and that 68nF at C2, not 470nF?

I've used 6.5k resistors as didn't have any 6.8k left... and yep I followed the 'TL072' parts guide so used the 0.068uf / 68nf cap there...

I habitually use #3 or #5 from the Tonepad wiring doc (in your post), depending on whether I'm using a Millennium-2 or a 3PDT.  Works like a dream.

Where do I get this 'millennium board' from? I'm using Diagram 1, I assume that should work just fine for now?

Have you tried checking continuity at various points on the board?  Set your meter accordingly, put one probe on the battery clip "-" (without the battery connected) and check all points on the board (and on your jacks) that are supposed to be "ground" (green on the tonepad diagram).  Now do something similar with battery clip "+" and all the 9V points (red on the tonepad diagram).  Now (or first!) check that there's NO continuity from the battery clip - to +.  Also: with the battery connected, the pink V_REF trace should be 4.5V.

I did do a few tests last night, and it all looked good. I will follow your steps in a few hours and report back the results. I feel I may have wired it up wrong, i've never used a DPDT switch before, but followed instructions. Again, will double check it all and get more pics up if I can't find any more problems..

If diodes are blown will that cause any of these problems? how can i test this?

[Hav]

right!

im getting '1' on my DMM when I try and find continuity on the negative side of things... I assume that means there is nothing happening! Positive rail is all good! Where to look?!

[Govmnt_Lacky]

If you are reading 8.9V on Pin 4 of the IC when it is removed.... YOU HAVE A SHORT BETWEEN V+ (9VDC) and GND SOMEWHERE!

Remove power from the circuit and remove the IC. Put the DMM black lead on the Pin 4 spot. Put the red lead on the Pin 8 spot. Tell me how many ohms you are reading.

I am willing to bet it is less than 50  

Somewhere you have a short and need to locate it  

EDIT: Quick tip.... check to make sure you wired your Input jack correctly for battery shut off..... if you are using a battery 

[Hav]

If you are reading 8.9V on Pin 4 of the IC when it is removed.... YOU HAVE A SHORT BETWEEN V+ (9VDC) and GND SOMEWHERE!

Remove power from the circuit and remove the IC. Put the DMM black lead on the Pin 4 spot. Put the red lead on the Pin 8 spot. Tell me how many ohms you are reading.

I am willing to bet it is less than 50  

Somewhere you have a short and need to locate it  

EDIT: Quick tip.... check to make sure you wired your Input jack correctly for battery shut off..... if you are using a battery  

yep your right! I definitely have less than 50! its at 0!!! if i set it too '200m' on DMM i get 0.02!!

Where else can this short be? can it be a dodgy switch / wrong way round transistors?