EQD Tone Job clone issues (PedalPCB)

[AROLB]

hello all! second post here. i've built a unit combining several circuits to incorporate a spring tank into a mixer setup. it has a tone job circuit (Box and All EQ from pedalPCB) on the fx return – during the testing phase for some reason the whole treble & mids section aren't functioning, but the rest of the circuit is working well. anyone might have an idea why and a possible fix? here is the schematics
https://docs.pedalpcb.com/project/BoxAndAll-PedalPCB.pdf

here are some photos of the board as well. im still improving on my soldering and this one is particularly messy as i re-soldered quite a lot of it to try to figure out a solution.

besides the issue, both bass and volume controls are working great and the board is working within the chain, but just wana try to get treble and mids working too so there's more tonal control over the verb!

again many thanks!!
rai

[ElectricDruid]

Checking your component values from the photos, it looks pretty good to me. Certainly nothing leaps out on first look.

The soldering looks under-heated though. Those blobby joints! Ugh! Get your soldering iron tip clean (the brass wire stuff is better for this than a wet sponge because it doesn't cool the tip down so much) and make sure it's hot and wetted with solder.

For most of those joints, I'd clean the old solder off with a solder sucker, and then re-do them. After that, I think you might find it springs to life.

[AROLB]

Hello Tom thanks so much for the quick reply and looking into it!!

Ah I see that's why I've been getting blobby solders. Been worried about overheating components but turns out it's the opposite.

There must be break at a particular spot in the circuit if the whole bass + volume section is still working? Want to see if it's possible to minimise resoldering as it's gotten quite deeply embedded amongst the other boards in the unit.

Cheers
Rai

[antonis]

>off topic<

IC1.2 could serve as Vref stabilizer, or even as separate band op-amp (e.g. for MIDs) rather than unneeded output buffer..
(IMHO..)

[ElectricDruid]

The Bass, Mid and Treble controls are all part of the same (second) op-amp stage. If the Bass control is working, then there's nothing fundementally wrong with that op-amp stage, and it's likely that the problems with the Treble and Mid controls are down to a bad connection on one of the components related to those sections. That's quite a few possible joints. Sorry, but you're going to have to re-do quite a few to make sure. Certainly R4, R5, R7, R8 and C3, C5, and C6. Plus check the two pots.

If the volume is working, then the third op-amp stage must be working too, so that's a good sign. And we know the first op-amp stage is working, because if it wasn't we wouldn't have signal this far anyway!

Get the excess solder off those resistors I mentioned for starters and re-do those joints, and then let's see where we are. It's possible (in a *nice* version of reality!) that nothing else is required.

[ElectricDruid]

>off topic<

IC1.2 could serve as Vref stabilizer, or even as separate band op-amp (e.g. for MIDs) rather than unneeded output buffer..
(IMHO..)

I agree, Antonis. It would have been more sensible. It's an odd design choice to waste it doing nothing when there's a couple of things it could have been more usefully employed doing. Oh well...

[bluebunny]

Been worried about overheating components but turns out it's the opposite.

Yes, it may sound counter-intuitive, but you need a hot iron.  The aim is to get in and out quickly.  The way to do this is to have the iron hot enough that the solder melts quickly so that it flows.  Warm enough so it goes gloopy like a paste isn't enough and will leave you with bad joints.  As with many things: practise, practise, practise! 

[PRR]

...Ah I see that's why I've been getting blobby solders. Been worried about overheating components but turns out it's the opposite....

I once bodged the power regulator on a PC motherboard to run a newer (hotter) CPU than it was made for.

Ran fine. But I noticed the power transistor was floppy in its solder holes. The solder joints were MELTED from transistor heat. Yet it worked OK (for the moment). Big Silicon WILL "run" at molten solder temperature. It may leak like a fly-screen water-pipe, it may stop working in an hour, but solder-hot is NOT instant death to Silicon, or most electronic parts.

Also: go to the resale/junk shop and get a couple semi-broken VCRs for a buck each. Cut the PCBs out and practice de-soldering and soldering nice clean joints. The factory joints are 99.99+% good so are useful examples to imitate.

[AROLB]

hey tom and everyone thanks for helping!! just got back to my desk to try this fix...

it's likely that the problems with the Treble and Mid controls are down to a bad connection on one of the components related to those sections. That's quite a few possible joints. Sorry, but you're going to have to re-do quite a few to make sure. Certainly R4, R5, R7, R8 and C3, C5, and C6. Plus check the two pots.

re-did these components as suggested, with a hot iron no less, unfortunately no changes at all... just glad i didn't make anything worse!

any suggestion on the next thing to try?

at the moment im putting an eq pedal in the series with it and working well that way so not end of the world if i can't get this Box And All EQ fully working but wouldn't mind giving it one last shot.

thanks again
rai

[ElectricDruid]

Humm, that's a shame. Could we have another photo of the improved soldering please? Just so we can Oooh and Aaah over its present beauty after its initial ugliness, you understand

I suppose we should have a look at the voltages to make sure.

Get your multimeter out, put the black probe on the input jack ground, and test the voltages with the red probe on the pins of the two op-amp chips. Pin 1 is top left, then work around anticlockwise to pin 8. That'll give us a good idea if there's anything untoward going on.

Good luck!

[AROLB]

hello! glad this is back online so i can carry on troubleshooting this.

Could we have another photo of the improved soldering please? Just so we can Oooh and Aaah over its present beauty after its initial ugliness, you understand

haha ok here's where it got to.... the lighting is making it look even worse!! i hope it's a small improvement to the previous effort



moving that pot repeatedly to access the soldering hasn't been great so by now i've joined the pot pins to the board with wires.

and here are the readings from the op-amp chips

ic2
pin
1  4.48
2  4.48
3  4.45
4  0
5  4.45
6  4.48
7  4.48
8  8.25

ic1
pin
1  4.47
2  4.47
3  2.23
4  0
5  2.25
6  4.45
7  4.47
8  8.26

thank you!

[AROLB]

I suppose we should have a look at the voltages to make sure.

Get your multimeter out, put the black probe on the input jack ground, and test the voltages with the red probe on the pins of the two op-amp chips. Pin 1 is top left, then work around anticlockwise to pin 8. That'll give us a good idea if there's anything untoward going on.

Good luck!

hey there – just bumping this up quickly. see the voltage figures below. thank you so much!

[PRR]

The DC voltages are OK. (the low numbers on pins 3 and 5 are because your meter loads the 1Meg bias resistors.)

[AROLB]

The DC voltages are OK. (the low numbers on pins 3 and 5 are because your meter loads the 1Meg bias resistors.)

great to know, thank you! in that case anything else i should try in terms of getting that section to work?

cheers
rai

[ElectricDruid]

Sorry Arolb, but that soldering still looks awful. It reminds me of this:

The voltages look ok, so something is working, which is good. If the Bass and Volume still work, but the Mid and Treble don't, then the problem can only really be in the parts associated with those two controls.
With the power off, you could check the resistances to help find the problem. For example, the Mid control is a chain of three resistors (R5, Mid pot, R8) from C2 to the -ve input. You should get 3K3, then 100+3K3, then 46K (the last reading across the whole chain is in parallel with the TReble and Bass chains). I suspect you won't get these readings, and the point at which things go wrong will give you a good idea which joints aren't good.

[zeropluszero]

Replying to follow, I have a Tone Job with the exact same issue.

Images
https://imgur.com/a/rmnzFBt

[Locrian99]

Interesting, not that this helps the trouble shooting at all, but I have built a few of these with a few small mods to use as a preamp before a tp3118 and never had any issues with them.  But both of you having an identical issue seems very odd.   

[zeropluszero]

Yeh, and I'm going to have to unbox it to do the resistance measuring I think.
This was my first pedal and I was pretty proud that it seemed to be going so easily haha.

[Locrian99]

Yeh, and I'm going to have to unbox it to do the resistance measuring I think.
This was my first pedal and I was pretty proud that it seemed to be going so easily haha.

I would take a few pics and post over on the trouble shooting forum over at PPCB before I go too crazy.  There may be someone super familiar with the circuit or if both of you are having the same issue it might be something that's popped up before.   

[zeropluszero]

Yeh we've already done that - https://forum.pedalpcb.com/threads/box-and-all-tone-job-treble-mids-issue.18806/