To de-clutter the main thread and kich off some modding endeavours, here some info on modding your Böhrindja TD3 box.

I hope the modular folks are not annoyed too much, but interfacing with modular is kinda logical even though this is not a module as such.

As the TD3 main thread has quite derailed a coupla times: no bashing of users, spamming or sht--head actions, please! personal issues or extreme detail info can be exchanged via PM; I personally am interested in posting/discussing results.

All this in the best faith, so let's muster up our inner Bob Rosses

Some prelim observations are to follow soon, but first things first:

1) There are plenty trimmers - all accessible form the underside, so you just need to take off the bottom of the chassis for adjusting vco, vcf or vca

2) Behri went the open music labs route for replacing the ba662

3) there is space for mods

4) plenty of piccos: https://imgur.com/a/MMNifIr

I am not affiliated, just a person interested in mods. Also, I'm not a 303 expert, so please, again, be gentle!

edit: here' a collab doc for the pcb inventory and a link to the tb303 service manual

https://yourpart.eu/p/TD3_Inventory

http://dl.lojinx.com/analoghell/Rola...rviceNotes.pdf


edit 5000: deleted links to older guides and just upped the most recent (V1.999) here: https://gearspace.com/board/attachme...2&d=1579634540

WoW - thanks for your detailed photos Maffez

Maffez I am really looking forward to this one from you

When mine arrive I am very tempted to shred one of them with your work

Seriously you are a breath of fresh air

Cheers Maffez, great photos & thanks to the guys at Behringer for including the trim pots etc

looking forward to tinkering about with it.

Awesome! Maffez in Hero-mode again...

fanx guys!

just in the first rush of digesting info and will need to take a break for life, love and groceries shopping stuff, but some (still tentative) prelim info:

devilfish options are go! all sections are discrete and there is space for additional pots and sockets and what have you

I can barely contain my excitement right now



Gonna have to get rid of those CapXon electrolytics for some nice Panasonic or Nichicons though.

Places for switches, sockets and potentiometers:

Backside:
There is enough space for sub-miniature switches on the back just over the DC input socket, usb and midi sockets if you install them vertically. Over the decay potentiometer there are two e-caps, so unless you relocate them, there is no space for additional switches/pots. There is space over the pots of the distortion section. Finally there is enough space on the lower part of the backside underneath the Behringer logo.

Top:
You have enough space for an insulated solder lug potentiometer or horizontal print potentiometer in places where there are no capacitors underneath the chassis (see backside). And guess what – there is plenty of space in the area of the Behringer logo underneath the led.
The PCB allows for installing a second row of sockets over the existing one (you need to scrape off a bit off the plastic spacer over the filter input socket, but the rest is easy). Installing 3.5 mini jacks (tayda) vertically is okay if you bend the solder lugs. Common sub miniature switches may be too deep for vertical placement as is.

Front:
Like on the RD8, there is quite some space between the PCB and the front of the chassis, which means deeper components such as switches and pots can be placed here most easily.

I'm so glad this thing has trimmers and seems to be very mod friendly.
Less hacked up OG 303s also seems like a nice side effect.

Here's to hoping this will shut up some of the corksniffers from the other thread

Excited about this thread!

First request: super simple idiot-proof CV-to-filter mod please

Subscribed. Solder iron heated. Coffee coins ready!

So what do i have to do to get 100% right sounding slide?

For the people that think it's too bright sounding, can those trimmers turn it down for that darker tone?

Yep, VCF Offset

dunno yet

yup, vr1

Nice, I actually like the low end more than the high end on the original TB. That sound of the resonant bass ripping is fantastic.

@ Maffez: can you have a think about Accent Out? (Roland) slides work nicely (out of mc-202) so a solid accent CV to assign for an external unit would be cool.
(tt303 mkII has it)

have a couple on my list - accent on 303 is 0V = on, so use could be limited to rolandish stuff, but it's surely possible

been skimming xoxbox pages with loads of cool info

thing is the pcb needs to be inventarised (is this a word?), so any help here is welcome

just found vcf cv in, and more to follow

YES!!!!

for the vcf offset is there a trimmer you can use a screwdriver on? or do you need to solder a trimmer to it?

You can adjust it with a screwdriver, no soldering iron required.

great news! i could only see screws on the osc offset and osc scale. vcf offset is like a dark hole, must be a black screw then?

This is how it looks on the parts side of the PCB (Thanks to Maffez for the photo)



you can still adjust it from the solder side though

man that is a beautiful sight! thank you.

do you know what VCA balance does?

We need someone to video themselves messing with those trim pots.

If all that is required is to have it so that when the accent out is at 0V you get a positive voltage out then a simple NOT or NAND gate is all that is required.

You may need to tie the input to the NAND/NOT gate via a resistor to high (not to sure on the value) and the output again via a resistor to low but I am not too sure on that. If it's a DC output then a diode on the output from the TD3 might be useful if you are tying the input to high as it would remove any chances of backfeeding the accent circuit on the TD3 via that resistor.

So something like a 4069 CMOS NOT gate IC.

It could also be done with a simple transistor circuit as well and a quick search online shows up a few contenders for a simple invertor circuit.

At least it's not trying to convert a Strand analogue dimmer, as that uses 0 - -10V not 0 - +10V as everything else does, although it is not something I have ever tried or would want to try to do.

I've no idea, might be for adjusting the maximum volume, could need it if you change the capacitors for example.

Or it could be to do with the transient click or something?

First I would use a multimeter to measure the value of the variable resistor as it was set at the factory, so you have a "default" value to return to, then just twiddle away to your hearts content.

I guess it nulls the VCA offset.

Let the sequencer run some pattern.

Set(hold) SAW/SQUARE switch to (not existing) middle position so you have no sound. (Usually this is possible, don't know how well this works on the Behringer. )

Minimize the clicks you still hear by adjusting VCA balance TRIM.