three O three mod

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nologin
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Re: Have you seen the inside of devilfish?

Post by nologin »

Finally no need to probe again, i found out where the problem comes from. The RD6.8EB3 and RD15EB3 diodes that a guy was selling on the RE-303 forum, are fakes, these diodes are badged properly, but the body is smaller. :doh:
I unsoldered the diodes from the TB303 and resoldered them to the RE303 and like magic the RE303 works fine. :party:
However, the TB303 has the problem of detuning with those famous counterfeit diodes. :omg:

But i wonder what diodes are present in the second RE303 that i was lent. I'm going to take it apart tomorrow and inspect it with a magnifying glass. Knowing that it bellowed even more than mine.

Edit: According to the things i had noticed, it was the 15 volt that was the problem, so D42 is the source of the detune. I'll check on the RE303 i lent, but I'm pretty sure in advance that the RE15EB3 replacement diodes, are alternatives that don't do the job properly. I'll checked.


The fakes diodes:
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Re: Have you seen the inside of devilfish?

Post by guest »

glad you got it all sorted. it definitely sounded like it was just an issue with the 15V, and that diode sets that voltage.
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nologin
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Re: Have you seen the inside of devilfish?

Post by nologin »

Thank you for your help. I didn't think it was the diode at all, as the problem was occurring on two RE303s.
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Biff
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Re: Have you seen the inside of devilfish?

Post by Biff »

Did you create the second oscillator or were you using pre-existing schematics/strip board layouts? Either way, would you be kind enough to send me the info? I am trying to add a second oscillator to by TD-3 and am getting stuck on which transistors to use of what I have amongst other things. Thank you!
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nologin
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Re: Have you seen the inside of devilfish?

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It's a VCO TB303 duplication, sorry i have no idea what transistors are needed for TD-3. I don't want to try to do this, i think TD3 is too fragile and not suitable. You should first buy a TD-3 MO and check if the internal power supply is different from a basic TD3. Because it probably won't work properly if you add a 2nd VCO.
I will however try to do something with Cyclone analogic TT303, i need someone to lend me one, I need a crash test dummy.
But i don't think it will work properly with TT303, it's too different a clone from the real TB303. But I'll still try to do something.

Because in the end I had great difficulty getting it to work well with a RE303 which is the closest to the real TB303.
The easiest for mods is the x0xb0x, because with its external transformer, it's the most adapted.
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Biff
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Re: Have you seen the inside of devilfish?

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Thank you for the suggestions. I’ll probably venture out like you said and/or see how much room there is in amperage for add-one. The fun continues!
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nologin
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Re: Have you seen the inside of devilfish?

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I looked at what diode was soldered in the RE-303 that I was lent, knowing that there was even more detune than with the RD15EB3, the RD15EB3 which is probably fake. :omg:
I couldn't unsolder the diode in place, the tabs are too thick compared to the holes, the diode is firmly stuck. So i inspected with a magnifying glass, apparently from what i can read it's 85B15, so probably a BZX85B15.

Image

Does anyone have the RED15EB3 datasheet?
Because i need it to try and find a better equivalent.
Otherwise I'll be forced to buy all kinds of 15V zener diodes and try to find good ones. :doh:
Knowing that I'm giving up the idea of finding NOS RD15EB3s. But it must be possible to find pulled. :hmm:
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Re: Have you seen the inside of devilfish?

Post by guest »

heres a datasheet for it:
https://www.datasheets360.com/pdf/4984511482801156417

it lists it as a zener voltage of 14.42-15.02V. the one you have might be fine, and you just got a bum version.
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nologin
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303 VCO2, and others

Post by nologin »

Thanks for datasheet. I'm going to replace the case, with a 3D printed plastic one, i find aluminium cases unsuitable for mods. Normally i will mod some for friends. But in the future there may be a different version for DIYers. My TB303 which is mint is back to original. I had built RE-303 with the idea of modifying it from the start.

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Re: Have you seen the inside of devilfish?

Post by guest »

wow, thats a whole new beast! thanks for sharing the video.
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nologin
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Re: Have you seen the inside of devilfish?

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Video made quickly, with poor sound quality,
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Re: Have you seen the inside of devilfish?

Post by nologin »

I posted other vids:







Last edited by nologin on Sun Nov 27, 2022 10:31 am, edited 1 time in total.
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three O three mod

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Biff wrote: Fri Nov 18, 2022 6:11 pm Thank you for the suggestions. I’ll probably venture out like you said and/or see how much room there is in amperage for add-one. The fun continues!
There is also the stability of the osc1 which is very important. In the past I tried a VCO2 kit for x0xb0x, i was quite disappointed with the result, i re sold it right away, the idea was good but it was like something not finished.
As the VCO2 is like a slave to the VCO1 tune, to get something coherent, it is important to have a stable and accurate master oscillator. For more accuracy, all resistors after the IC that decodes the pitch note information into an electrical pulse should be replaced with 0.1%. And to calibrate the oscillators more accurately, i've replace the VCO trimmers with 10 turns. And i guess the TD3 VCO exponential is worse because there should be no thermal contact between the double transistor and the thermistor. I think it would turn out like a potato, you can try, but I think it's much easier to do with an x0xb0x. You won't be able to replace all the resistors.
Well, if it's designed the same way, i had looked at the TD-3 schematic once, a friend wanted me to make some basic modifications, i quickly understood that some modifications were not feasible, if i remember correctly there is no 4066, but something else. So i thought it wasn't worth it, I advised my friend to buy TD3MO instead, although i hate to advise a friend to buy this brand. :mrgreen:
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Re: three O three mod

Post by Biff »

nologin wrote: Thu Nov 24, 2022 10:14 am
Biff wrote: Fri Nov 18, 2022 6:11 pm Thank you for the suggestions. I’ll probably venture out like you said and/or see how much room there is in amperage for add-one. The fun continues!
There is also the stability of the osc1 which is very important. In the past I tried a VCO2 kit for x0xb0x, i was quite disappointed with the result, i re sold it right away, the idea was good but it was like something not finished.
As the VCO2 is like a slave to the VCO1 tune, to get something coherent, it is important to have a stable and accurate master oscillator. For more accuracy, all resistors after the IC that decodes the pitch note information into an electrical pulse should be replaced with 0.1%. And to calibrate the oscillators more accurately, i've replace the VCO trimmers with 10 turns. And i guess the TD3 VCO exponential is worse because there should be no thermal contact between the double transistor and the thermistor. I think it would turn out like a potato, you can try, but I think it's much easier to do with an x0xb0x. You won't be able to replace all the resistors.
Well, if it's designed the same way, i had looked at the TD-3 schematic once, a friend wanted me to make some basic modifications, i quickly understood that some modifications were not feasible, if i remember correctly there is no 4066, but something else. So i thought it wasn't worth it, I advised my friend to buy TD3MO instead, although i hate to advise a friend to buy this brand. :mrgreen:
Thanks for the insight! I’ve been back and forth with using a TD-3 or just combining 2 X0X hearts and finding a sequencer, which then gets elaborate (I’m thinking a Division 6 mini seq since it has an accent/aux and can do duophonic sequences). For the TD-3, I was thinking of doing a higher PSU for a second osc, i have some Electrosmith 3340 sub-module, but it sounds nothing alike.

Basically I want to make something like a 777 which I regretfully sold a few years back.
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Re: three O three mod

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Unfortunate it was not to sell 777. i didn't know this electrosmith, it's interesting, i have PCBs to build a modular, but i don't have a VCOs.

If you adapt this, it's +15/-15V, you need to add ICL7660 or better an external +15/-15V power supply, it's good to have all these waveforms, you'll be able to modulate considerably the oscillator 1. On the other hand you'll have an oscillator that won't have the 303 type at all, there's really a sonic difference between the false square of 303 and a real square wave.

I'm starting to try and design a smd version, I'll have to get 5 made to check if it's OK, if you want i can supply one for the price it cost me. But I don't know if there is space to install it in a TD3 case. There will be no Xmod.

So far what i've done it's uggly with the stickers for the added functions, but I'll make some adjustments and install in a plastic case.
The smd board will have less mods, there will be VCO2 waves SW, VCO1 gain, VCO2 gain, tune 2, fine tune 2, VCO sync, drive 1, drive 2, FM/filter tracking pot (+FM/filter tracking pot selection switch), Accent decay pot, 4poleSW, Filter low end SW.

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Biff
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Re: three O three mod

Post by Biff »

That sounds awesome. Let me know when you have the PCB made and I’ll gladly take one.

Space shouldn’t be an issue for me. I’m making a larger case to make room for everything. :tu:
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Re: three O three mod

Post by Altitude909 »

if youre interested in collaborating on 3d printed case design, let me know. I've done a number of them and been looking to do a modded out 303 for a while but couldnt find the motivation to finish my mod kit
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Re: three O three mod

Post by Biff »

That’s awesome! I am attempting to make a design that looks like it should be on the Death Star. People used to say my Future-Retro black/grey Revolution looked like a prop from the Death Star, so I figured I’d go full-on in that direction. With all that said, I’ll hit you up if I decide not to go that direction. 3D printing a new case sounds like a great idea since just an extra few centimeters in any direction would make it much easier to add on tons of stuff.
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