BUILD THREAD: 266-style PCBs

roman_f · Post by **roman_f** » Sun Jul 29, 2012 4:12 am

I am feeding it via a 9V AC/AC Adapter to an A-100 Busboard (the "small" one which can feed +4 modules). It is working fine for testing.

this transformer need some normal PSU with high current

On the -12V rail on the busboard the light is very dim, e.g. either a high load or a near-short.

this is strange, since the -12Vs rail is not used at all if L2 is not soldered

have you tried disconnecting a wire from pad 1 and measuring +15Vs?

roman_f · Post by **roman_f** » Sun Jul 29, 2012 4:18 am

janvanvolt wrote:Let be more specific: I am feeding it via a 9V AC/AC Adapter to an A-100 Busboard (the "small" one which can feed +4 modules). It is working fine for testing.
On the +12V rail on the busboard light is normally lit.
On the -12V rail on the busboard the light is very dim, e.g. either a high load or a near-short.

The measurements i took are from the THRU pad, e.g. i am not getting the voltages (15/-15V) out.

my engineer friend reports that you should use L3/L4 inductors from the BOM, the ones you're using won't work with such current level

zoot horn rollo · Post by **zoot horn rollo** » Sun Jul 29, 2012 11:15 pm

Hi Roman,

I'd like to build my buchla format pcbs to be 1v/oct rather than 1.2v/oct.

Is this as easy as changing a few resistor values? If so, do you think you could let me know which resistors? (I assume that I can then change these resistors to the values in the 5U bom).

Thanks

roman_f · Post by **roman_f** » Mon Jul 30, 2012 12:59 am

zoot horn rollo wrote:Hi Roman,

I'd like to build my buchla format pcbs to be 1v/oct rather than 1.2v/oct.

Is this as easy as changing a few resistor values? If so, do you think you could let me know which resistors? (I assume that I can then change these resistors to the values in the 5U bom).

Thanks

use 2K 0.1% resistor to connect the outputting banana with the related pad on the PCB (instead of wire), connect same banana with a ground with 10K 0.1% resistor

you should do this after you have the PCB attached to a front-panel
ground may be found nearby if you remove the mask off the ground-fill area, or on one leg of pots

zoot horn rollo · Post by **zoot horn rollo** » Mon Jul 30, 2012 4:14 am

Thanks Roman!

janvanvolt · Post by **janvanvolt** » Tue Jul 31, 2012 5:49 am

Roman,

just verified your first page - and saw probably my error as i am trying to feed the power -12V instead of +12V...

--jan

roman_f · Post by **roman_f** » Tue Jul 31, 2012 11:23 am

janvanvolt wrote:Roman,

just verified your first page - and saw probably my error as i am trying to feed the power -12V instead of +12V...

--jan

please report me on you progress, i would be happy to know if you fixes this

roman_f · Post by **roman_f** » Tue Jul 31, 2012 12:27 pm

i've just tested it again - works great here

1) i need to wait maybe 10 seconds after i power up the system, that's normal.
2) IC15's is pretty hot. you might want to put a heat sink on it

but everything works perfect

synaptech · Post by **synaptech** » Thu Aug 02, 2012 1:21 am

Just a note on radiokoala's Mouser Projects - it looks like the eurorack 3+4 project lists both types of pin sockets (gold/tin and dual wipe). The gold ones will run you ~$30 so be aware when placing your order!

Thanks for throwing that together though radiokoala, saves me the headache of importing BOMs!

L-1 · Post by **L-1** » Thu Aug 02, 2012 2:47 am

I've taken quick look at the Euro BOM. C37 is missed.

roman_f · Post by **roman_f** » Thu Aug 02, 2012 3:07 am

synaptech wrote:Just a note on radiokoala's Mouser Projects - it looks like the eurorack 3+4 project lists both types of pin sockets (gold/tin and dual wipe). The gold ones will run you ~$30 so be aware when placing your order!

Thanks for throwing that together though radiokoala, saves me the headache of importing BOMs!

transistors are missing in this Mouser Project as far as i see
3904, 3906

roman_f · Post by **roman_f** » Thu Aug 02, 2012 3:11 am

L-1 wrote:I've taken quick look at the Euro BOM. C37 is missed.

for 12V operation you should skip it, the value is in the schematics

frozenkore · Post by **frozenkore** » Thu Aug 02, 2012 8:59 am

I'm assuming these are these CA3080s will work too but I wanted to verify before I order them with my switches: http://www.smallbearelec.com/servlet/Detail?no=219

Here is more details of it:
IC CA3080AE
8-pin DIP OTA for the Ross/Dynacomp. These are the re-issue parts made by Rochester Electronics from the Intersil masks.

roman_f · Post by **roman_f** » Thu Aug 02, 2012 9:22 am

frozenkore wrote:I'm assuming these are these CA3080s will work too but I wanted to verify before I order them with my switches: http://www.smallbearelec.com/servlet/Detail?no=219

Here is more details of it:
IC CA3080AE
8-pin DIP OTA for the Ross/Dynacomp. These are the re-issue parts made by Rochester Electronics from the Intersil masks.

should work
i buy my 3080s in china from the provider in BOM seller, but since you have them @ smallbear and you need only one - do it

frozenkore · Post by **frozenkore** » Thu Aug 02, 2012 12:33 pm

Cool, thanks!

janvanvolt · Post by **janvanvolt** » Sat Aug 04, 2012 5:45 pm

Back to my debugging adventures now:

a) fixed the +/- Doepfer connector, so that the + rail is only used and not the neg one.

Next problems:

a) On Thru Pad, +15V gives 14.97 (well that seems right)
b) On Thru Pad, -15V gives me 0.47V (seems odd...)

and ... some part is getting hot, but need to find out which one, but it seems to be the regulators.

Thougts ?

roman_f · Post by **roman_f** » Mon Aug 06, 2012 8:45 am

janvanvolt wrote:Back to my debugging adventures now:

a) fixed the +/- Doepfer connector, so that the + rail is only used and not the neg one.

Next problems:

a) On Thru Pad, +15V gives 14.97 (well that seems right)
b) On Thru Pad, -15V gives me 0.47V (seems odd...)

and ... some part is getting hot, but need to find out which one, but it seems to be the regulators.

Thougts ?

it seems that we have to make it work without a 12-15 transformer on 12Vs

it worked perfect on my bench PSU, but when i fit it to my doepfer case - promlems start
gimme a day or two, i'll recount the resistors for QRV
or probably someone can help me:

QRV - gives 1.2V/pct quantized voltages which are then scaled to 1v/oct using 2 0.1% resistors
it works on 15Vs, but if i power it with 12Vs - the quantization goes down
please check the schematics, it's probably just a couple of resistors to change

roman

roman_f · Post by **roman_f** » Mon Aug 06, 2012 10:59 am

i've tested the module @ my doepfer case now

installed 2 jumpers
i didn't install:

D12, D13, IC15, IC14, L4, L3, R44, C14, C41, C40

@ 15Vs - everything works perfect
@ 12Vs - everything works, but the quantization of QRV is incorrect

so the only thing is to correct the QRV

[video][/video]

camelneck · Post by **camelneck** » Fri Aug 10, 2012 3:54 am

Roman,
I've recently returned to the forum after being on an extended break from DIY synth building. (I had to undergo back surgery several months ago.)

I must admit that I was surprised to find out about this wonderful project and how quickly it came together. I'm only hoping that I am not too late to partake in this great adventure.

Are any of the PCB sets still available or are they all sold out?

If you are sold out (heaven forbid), is there any chance you might do another run sometime in the future?

janvanvolt · Post by **janvanvolt** » Sat Aug 11, 2012 6:55 pm

Does not install R16 and R35 also apply to eurorack ? if yes: fine, if no: what are the values ?

spotta · Post by **spotta** » Mon Aug 13, 2012 9:12 am

Hi

Is is all good to populate Euro PCB3 yet, I am using the schematic dated 26th July which has the amendments re R6 & R7 and the insulating tape.

mayanspring · Post by **mayanspring** » Mon Aug 13, 2012 11:10 pm

this is the third related thread I am going to throw this out in, but lacking time and skill I am hoping someone out there is building an extra Eurorack one or planning to do so that they would sell me.
don't have time or ability to really jump into this on my own, but I think it looks like a great module.

PM me if you think you can help.

ringstone · Post by **ringstone** » Thu Aug 16, 2012 9:04 am

Any progress on the 12V Euro issues? My current mouser order is on hold for the time being... not having to buy the voltage converters will certainly improve the overall cost for this project!

Cheers
Blair

janvanvolt · Post by **janvanvolt** » Thu Aug 16, 2012 7:21 pm

Well. I asked some people and waiting also for answers :-) In the meantime the 266 will be finished, except the Panel and the 910pf caps. Does it have to be exact 910pf ? What is so magical about this value ?

... and the 266 works by the first power on after completion :-)

ringstone · Post by **ringstone** » Thu Aug 16, 2012 7:45 pm

janvanvolt wrote:Well. I asked some people and waiting also for answers :-) In the meantime the 266 will be finished, except the Panel and the 910pf caps. Does it have to be exact 910pf ? What is so magical about this value ?

... and the 266 works by the first power on after completion :-)

Actually the Mouser link in the BOM is for 1000pF (1n) caps, so I guess not THAT important. I just splashed out on some silver micas, they were significantly less expensive than anything Mouser offers in that value (nearly $4 a cap!).

Cheers
Blair

MUFF WIGGLER

MUFF WIGGLER

BUILD THREAD: 266-style PCBs