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TWO59 VCO module (Building Thread) by FEEDBACK
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page Previous  1, 2, 3, 4, 5, 6  Next [all]
Author TWO59 VCO module (Building Thread) by FEEDBACK
sduck
Sorry, I misread, and also forgot what those diodes do anyway. Never mind.

Not sure what you mean about the 12v power.

Jarno wrote:
Those are the diodes in the power supply section, and are meant to prevent reverse polarisation of the connector. This is not likely to happen (boxed header), therefore I replaced them by wires. Why do you think this is part of the problem?

Edit:
Mine is running on eurorack-standard voltages, so +/-12v (rather than +/-15v).

Edit2:
By the way, the picture above is of the functioning VCO, the one that does not function does have the polarity protection diodes.
Jarno
Not sure what the maximum voltage spec for the CMOS is, but the forward voltage drop caused by the diodes could keep it to just within limits for +/15v operation, but for +/-12v that's likely to be less of a problem (if it works on +15v with voltage drop, it'll work on +12v).

Well, replaced U2 and U4, and the THAT340, still sweet f*ck all. I guess there was going to be a moment like this, whishing I'd put everything in sockets (at the moment only the THAT340 is). On to the shaper first, I'll come back to this.
sduck
Who's running this on 15v? Why did this come up? Doesn't really matter, as it's a non-issue anyway.

I keep relooking at your pictures, and there are a few solders that look suspiciously like they might be cold solders - it's probably just a trick of the angle of the picture, but I also notice some of those suspicious ones don't have solder flow through on the other side. You might consider doing some reflowing. This may not be the problem at all, but just another idea to consider.
rithma
I hate to be *that* guy, but could you have maybe possibly hooked up the power backwards on the non functioning VCO?

(Im ONLY asking this because I have done it... maybe 15 times... every time searching long and hard for a more complicated answer to my problem...)
pbotsaris
I don't know if anyone pointed this out yet but in the BOM is 2 x 2.2K and it's supposed to be 3 X
strat-1
pbotsaris wrote:
I don't know if anyone pointed this out yet but in the BOM is 2 x 2.2K and it's supposed to be 3 X


Thank you. I will correct the bom list.
strat-1
UPDATE : I Corrected some typos in the manual, like wrong number of pots and other text mistakes.
Cryaaa
[EDIT] I realised that i soldered the JFET the wrong way round, i'll hopefully solve the problem, don't have my own oscilloscope though so I'll report back...... I'll leave this here to help others who might make the same stupid mistake d'oh! [EDIT]
I'm having trouvble with the sine output..... Other outputs look great, but i get a really weird sine shape.... Took pictures of the sine out, the trimpot for the amplitude adjust only affects the wide triangle portion of the wave. Wasn't sure what else to measure so I included pictures from the input of the Tl072 Portion that handles the sine shape, if anybody could give me any hints as to where I should start looking that would be great....... checked all solder joints already... I also have the Oscillator readings as CSV-files if that helps.


Siri
Ilpolainen wrote:
So I just thought to notice that you can add BOM THAT340 Mouser Part.No: 887-340P14-U.

Thanks for AWESOME job. Module not ready yet though. smile


+1, it is not mentionned in the BOM
Kan Kaban
Hi!, congrats for the two59. Just got the board+panel kit from modularaddict but realized I dont have the transistor+matched resistor kit.

Is there any chance to replace the 2N5457 with J105,J106,J107, etc; use trimers to find values, and how do I know when the value is just perfect?

Also, where can I buy just the trans+resist kit?

Thanks thumbs up
mritenburg
Anyone building two59 vco's and shapers to order? PM me if you are building and want some business.
secrethero303
mritenburg wrote:
Anyone building two59 vco's and shapers to order? PM me if you are building and want some business.


PM’d, not exactly building to order, but happy to help out.
rossgrady
Quick question: I ordered PCBs in November & received revision 1.2 boards -- is there still an issue with the incorrect route, and the need to manually connect pins 9 & 10 on connector 2, or was that corrected with this revision?

I looked at the boards I got & didn't see any manually cut traces, so perhaps this was resolved?

Are there any other differences with 1.2 boards that I should be aware of?

Thanks!
mattip
A question about the BOM:
C6 is listed as a 4N7 Polystyrene. But in the parts numbers examples are polypropylene caps. It is also a polypropylene cap in the photos in the build docs.
So should I use the styrene or polypropylene?

this:
https://www.mouser.com/ProductDetail/23PW247

or this:
https://www.mouser.com/ProductDetail/505-FKP24700-63-5

/m
humax5600
I have this part of Reichelt installed.
And it works fine

https://www.reichelt.de/film-capacitor-4-7nf-63v-rm5-fkp2-63-4-7n-p172 413.html?GROUPID=7164&START=0&OFFSET=16&SID=95XH61tqwQATUAAHk44qQ630bd 89e8774407bc0f7e5b85b7c8d52&LANGUAGE=EN&&r=1
mattip
Thank you. I think I order both and see if the styrene is too large. /m
strat-1
mattip wrote:
Thank you. I think I order both and see if the styrene is too large. /m


You can use any precision capacitor 1%-2.5% (capacitance tolerance)
It can be polypropylene or polystyrene.

I prefer Wima because of the price vs size vs results.
mattip
OK, thanks. I thought it was something with styrene and vco:s :-)
strat-1
mattip wrote:
OK, thanks. I thought it was something with styrene and vco:s :-)


It is smile

These capacitors provide high insulation, low leakage, low dielectric absorption, low distortion and excellent temperature stability.
airfrankenstein
hi
I'm about to order two complet TWO59kits and a shaper and would like to know what "expensive" parts I'll have to buy in addition besides the THAT340 ?
I'd built a J3RK 258J; this seems similar enough, but trying to get an idea of what my total build budget will amount two in addition to the the "full" kits purchase price (about 200 euros).

Hope someone can help
thanks
synthetek
airfrankenstein wrote:
hi
I'm about to order two complet TWO59kits and a shaper and would like to know what "expensive" parts I'll have to buy in addition besides the THAT340


The vactrols there are 5 vtl5c3/2 and 3 vtl5c3
windspirit
Hey, hope all is well. I recently built one of these using the rare parts kit (pcbs/ panel + transistors and pre-selected resistors). I am having 1 or two issues with my build:

1) Can't calibrate my VCO to 1v/o, when the trimmer is all the way open it is still too low of a range. Im guessing I can replace R2 with a lower value resistor to increase the range?

2) My sine doesn't look anything like a sine. Kind of a bummer since the kit was supposed to come with the preselected values. Adjusting the trimmer doesn't change anything (including the sine amplitude which I thought was odd). Does this mean that there is possibly an issue with my sine shaper circuit or that I should try the method for picking resistance manually instead? I can post pics of the board when I get to my office, all the other waves look fine.
strat-1
windspirit wrote:


1) I can replace R2 with a lower value resistor to increase the range?

2) My sine doesn't look anything like a sine. .


1) Don't change the value of R2. Something is wrong with the circuit.
2) I've built tens and tens of TWO59 VCOs, and always checking my stock of rare parts. A scope image will be very useful.
astroschnautzer
windspirit wrote:


1) Can't calibrate my VCO to 1v/o, when the trimmer is all the way open it is still too low of a range. Im guessing I can replace R2 with a lower value resistor to increase the range?

a faulty THAT chip was the problem for me... IIRC, it was a while ago I built this...
windspirit
Well, I missed the part about soldering the THAT chip directly to the board but afaik it was just for the spacing because you are supposed to use a large tempco correct? My issue might also be that I used 2 x 2k tempcos in parallel to get a 1k, I have a stash of smaller tempcos (still 3500 ppm) but I figured that the increased surface area would improve reliability with a smaller resistor. However, if there is a chance that the THAT chip could be faulty I would really prefer not to solder it directly to the board. Fortunately I have another one to test it with but Ive included some pics of the board in case there could be another issue.

Also I discovered like the gentleman above that my FET was soldered with the wrong pin orientation and thats what was mucking up my sine shape. Unfortunately I broke a leg on the FET desoldering it. Is it possible to use a J201 instead for the sine shaper? I have a few of them laying around, I know that I will have to use a different resistor pair for them.


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