ROG tonemender vero board problems

[otomo]

hi guys, my names thomas, and im relatively new to to wonderful world of electronics!

been an avid reader of lots of posts here, but cannot find the answer to the problem i've got.
built the tone mender from ROG groove 4 times now, and it always has the same problem... the tone potentiometers and switch do nothing!
i've gone around the circuit with an audio probe, theres signal going through when the board has no power, and louder and cleaner with power, but it goes all the way through to output. yet the pots and switch don't seem to have an effect.

ic pin out voltages for tlc2272 are strange

using a new 9v batter

pin 1   7.85
pin 2   7.85
pin 3   7.37
pin 4   7.85
pin 5   7.36
pin 6   7.68
pin 7   7.85
pin 8   8.93

i've checked this one over for loose solders, bridges etc, and this is also the fourth time i've tried. all resistors and caps and pots are as recommended.tested using a mp3 as input

anyone have any thoughts of the area i should be looking in? as i'm quite keen to figure it out myself....but need some clues!

cheers guys

[chumbox]

Hi Thomas

Now I'm no diagnosis whizz but start here with the troubleshooting post and see how you go:

http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

Beyond this I find with vero it's 98% a solder problem or 1% wiring of the 3PDT switch and/or 1% grounding issues.  Not saying this to be insulting, it's just it took me a long time to work out that most problems were simply solved by these things after about 20 builds. In most cases double and triple checking these three things with a clear calm mind resolved most issues first go. 

Sorry I can't be more help but good luck, you'll get it going in the end.  It's character building

[Elijah-Baley]

hi guys, my names thomas, and im relatively new to to wonderful world of electronics!

been an avid reader of lots of posts here, but cannot find the answer to the problem i've got.
built the tone mender from ROG groove 4 times now, and it always has the same problem... the tone potentiometers and switch do nothing!

It is your first pedal? If you have always the same problem is probably a mistake in your project or wiring, or somewhere else, indeed is hard to believe you make  the same mistake again and again.

Link us the layout and the wiring that you're following.
And some circuit's pictures.

[otomo]

hi guys, yea i agree that's its got to be something i'm consistently doing wrong!

with my audio probe the signal seems to go into pin 3 clean, but if i trace it away from the ic into the tonestack it becomes broken up and quiet and the pots still do not do anything. the signal can then be found on the output of the ic, but its the same sound as found in the pots, distorted and low. only change i've done was to remove the 500k level pot and replace with 22k resistor.


http://tagboardeffects.blogspot.co.uk/2012/12/runoffgroove-tonemender.html

just trying to get a few photos but thats what ive been following. cheers 

[duck_arse]

otomo, hello and welcome.

can you remove the battery from the connector and the external DC plug if you're using, and then measure the resistance between each lump of the batter snap and the board +9V and GND? please.

[otomo]

[otomo]

otomo, hello and welcome.

can you remove the battery from the connector and the external DC plug if you're using, and then measure the resistance between each lump of the batter snap and the board +9V and GND? please.

i've got a reading of 540k between positive and negative terminals on the board

[otomo]

two things that seem a little different to me from other tone stacks i've seen are that there's a bridge between pins one and 2, but the schematic for tlc2272 says these are out put and input

and i can't see a ground connection from the pots, is this because they are connected to ground through the enclosure/chassis?

[duck_arse]

the schematic shows pins 1 and 2 shorted, forming a voltage follower/unity buffer, so you want that connection.

what I wanted to know was if you had good connections from power supply to board. so measure resistance from board ground to batter snap, one lug should be 0R, the other something high. then measure from board +V to snap, same readings apply.

also, your build may be suffering from jaundice. too much yellow wire makes homer something something something. add some colour! some other colours! then you'll be able to follow the connections at a glance, as will we. the more colours wires, the easier the followings.

one lug of the mid pot goes to Vref, which is effectively 0V for the tone circuit. the pot bodies can be connected to ground/battery 0V via a seperate ground wire, or via the metal box and the jack sleeves.

[otomo]

yea it's pretty simpson esque, appologise!

so from board ground to battery += 0R
                                   to battery - + 2.8ohm

from board v+ to battery +=3.2ohm
                        to battery -= 0R

ah ok, i can see the v.ref now, coming off the two 1m resistors. And so the voltage follower on pins one and two is for very low impedance with a good/original output?

[otomo]

jus wondering about the voltage follower as the input into pin 3 is nice and clean, yet on the output of pin 1 and 2 its quieter and distorted, tired 4 chips with the same result in ic holders, so i guess im thinking theres something wrong with the power feed to the ic... closing in on an area atleast!

[duck_arse]

some more measures for you to do. those readings don't look right. can you power off, remove the IC, and measure resistance between pin 4 and pin 8 of the socket? also, just for fun, from pin 8 back to the batter snap, both lugs.

and, with no IC in the socket, power on and read the voltages at pin 4 and pin 8, pin 3 and pin 5.