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ARP 4035 VCF PCB anyone?
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3nity



Joined: Oct 10, 2008
Posts: 13
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PostPosted: Fri Oct 10, 2008 11:41 pm    Post subject:  ARP 4035 VCF PCB anyone? Reply with quote  Mark this post and the followings unread

Hi,

I was surfing through this topic, but I am looking for a direct replacement pcb layout to mount in my Odyssey II.
Has anyone ever played with this?

Thank you.
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Broadwave



Joined: Feb 16, 2007
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PostPosted: Sat Oct 11, 2008 1:27 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi 3nity,

I can do this for you, fairly easy as I've got the original PCB foils - but I'm off on holiday from 4th November.

I'll have to have a look and see if it's directly compatible with the MKII (the 4035 was designed for the MKI). If you're interested, I maybe able to get it done in a week or two... It'll cost about 75.00 USD.

If you can take a pic of the boards inside your Oddy, I'll be able to tell what you have... The MKII's were a bit of a hack job, some earlier versions used boards from the MKI, and some have the infamous Moog filter - it's all a bit of a minefield really : )

Andy.

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3nity



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PostPosted: Sat Oct 11, 2008 2:07 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi Andy,

Thanks for your quick reply.
My odyssey has the 4075.

I was wondering if you have the pdf for the original 4035 layout. I already saw your previous thread, but I could only find the 4023 pdf.

If you can, after you come back, please share with us.

Thank you again.

Cool
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Broadwave



Joined: Feb 16, 2007
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PostPosted: Sat Oct 11, 2008 3:38 am    Post subject: Reply with quote  Mark this post and the followings unread

Ah... The 4035 - Sorry I got the wrong end of the stick.

Yes the 4035 module will work fine as a replacement for the 4074, but a few component values will have to be changed on the VCF audio mixer.

I'm still working on the 4035 (it's a double sided board). But I'll try and get full details of both the original Module and My Eurorack module up next week.

Andy.

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3nity



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PostPosted: Thu Oct 23, 2008 12:55 am    Post subject: Reply with quote  Mark this post and the followings unread

Any update?
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Broadwave



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PostPosted: Thu Oct 23, 2008 6:42 am    Post subject: Reply with quote  Mark this post and the followings unread

Here you go,

Just one thing to be careful of, and that's the two FET's (2N5459), please watch the pinouts as you'll need to swap the drain & source pins (they may well work without swapping... I didn't take the chance).

The schematic for the original module is available from here:

http://www.arptech.synth.net/pdf/4035.pdf

The usual disclaimer applies, but I had no problems with the build.

Enjoy,

Andy.


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Last edited by Broadwave on Tue Oct 28, 2008 11:29 am; edited 1 time in total
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etaoin



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PostPosted: Thu Oct 23, 2008 11:21 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thanks Andy. I think I have a double sided bit of PCB left somewhere so I might give it a go...
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ericcoleridge



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PostPosted: Fri Oct 24, 2008 11:15 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for posting this. I've never made a double sided PCB, but I'm willing to try. I'll build your 4023 first though, and the dual VCO before that.
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3nity



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PostPosted: Sat Oct 25, 2008 12:36 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi Andy,

Thanks a lot for your collaborative efforts. Great job!

AndyR1960 wrote:
Yes the 4035 module will work fine as a replacement for the 4074, but a few component values will have to be changed on the VCF audio mixer.


What are the components to change?

Thank you again.

Cheers.
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Broadwave



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PostPosted: Sat Oct 25, 2008 2:07 am    Post subject: Reply with quote  Mark this post and the followings unread

3nity wrote:
Hi Andy,

Thanks a lot for your collaborative efforts. Great job!

AndyR1960 wrote:
Yes the 4035 module will work fine as a replacement for the 4074, but a few component values will have to be changed on the VCF audio mixer.


What are the components to change?

Thank you again.

Cheers.


Hi 3nity... PM waiting for you.


Andy.

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3nity



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PostPosted: Tue Oct 28, 2008 2:16 am    Post subject: Reply with quote  Mark this post and the followings unread

Ops,

No luck with this design. (In my Odyssey II).

Has anyone built it with success?

Please report your successful stories.

Thank you.

Rolling Eyes
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Broadwave



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PostPosted: Tue Oct 28, 2008 3:41 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi 3,

Any chance of hi-res pics of both sides of your PCB?

I've built several 4035 modules with no problems - I'd like to see if I can help.

Andy.

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3nity



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PostPosted: Tue Oct 28, 2008 8:51 am    Post subject: Reply with quote  Mark this post and the followings unread

AndyR1960 wrote:
Any chance of hi-res pics of both sides of your PCB?

I've built several 4035 modules with no problems - I'd like to see if I can help.


Hi Andy,
Thanks for your support.
Please find the pics enclosed.

I started with 4035, then I changed back to 4034, but no luck at all.
Probably I should build a test gig, and test the filter alone.
As you can see, I have used the equivalent TB331 that I had around, 2 BF245A as fets, and a simple 2-watt resistor instead of the tempco.

Any hints?

Respect,
3nity


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Broadwave



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PostPosted: Tue Oct 28, 2008 11:23 am    Post subject: Reply with quote  Mark this post and the followings unread

I've found something... My fault I'm afraid - DUH!

Next to the left of your 2W 1.8k resistor, on the edge of the board, you'll see two pads with no components soldered in - you need to link them with wire and solder through on both sides (see attached JPG).

This is the only thing I can see that could be the cause of it not working.

I've updated the original PDF... Apologies to all.


Andy.

Thanks 3


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3nity



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PostPosted: Wed Oct 29, 2008 2:25 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi Andy,

Thanks for support.

Did the mod, but unfortunately still no luck with this card. It doesn't seem to work properly.
I have a bad low freq. floor at the output, with nothing connected on the card (no input, no pots, no trim). I see about 2-3 Vpp on the scope!

Signal is present at the two fets gates: for a 0.5Vrms on the input, I get 30/40mVpp on them....

I tried a test rig, connecting the CVR trim between 18, 14 and 3, a 100K pot with a 22K resistor in series with it's wiper in pins 10, 2 and gnd,
another 100k pot for the cutoff, top on -15V, wiper in series with 150K to pin 4, bottom to gnd.

It doesn't change.

Probably I should redo the whole work again.

Comments are welcome.

Rolling Eyes
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ericcoleridge



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PostPosted: Thu Oct 30, 2008 10:59 am    Post subject: Reply with quote  Mark this post and the followings unread

What type of caps are those in both 3nity and Andy's pictures, the yellow and blue bulb shaped ones. They are tantalum?
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3nity



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PostPosted: Thu Oct 30, 2008 11:27 am    Post subject: Reply with quote  Mark this post and the followings unread

ericcoleridge wrote:
What type of caps are those in both 3nity and Andy's pictures, the yellow and blue bulb shaped ones. They are tantalum?

Yes.

2nd ATTEMPT

1) I remade the foil, since I realized that in the old one the emulsion was up, so I could get a more precise development.

2) I re-etched a new pcb, double-checking for shorted traces, and correct all the errors.

3) I mounted the whole board again. Now I have DIL sockets for the IC's, found the original CA3086 from RCA, and 2 BF245B.

4) Double-checked again for errors.

5) Reconnected the test rig, with the trimmer and the two pots.

6) Fired up!

RESULTS :

It immediately seems to be working.
Frequency and resonance controls respond correctly.

The mains hum is still there, but it depends on the fact that the board is not encapsulated in a screening can, so it picks up electro-magnetic fields from around, especially when near a transformer.

Now I'm tired.

Tomorrow I am fitting my new 4034 filter (I sticked to the old Tonus design) inside my old Odyssey II, and see what happens. Let's cross the fingers.

All for now.

Respect.

Razz
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Broadwave



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PostPosted: Thu Oct 30, 2008 1:08 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hey 3,

Really pleased you got it going - not sure what could be causing the hum though.

It's a great filter to use... I love it.

Andy.

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3nity



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PostPosted: Sat Nov 01, 2008 1:43 am    Post subject: Reply with quote  Mark this post and the followings unread

UPDATE

Finally I have fitted the 4034 in my Odyssey II.
The sound is somewhat moog-ish as you already know.
I like it.
Some issues (but this depends on the C-II board of the synth):
1) I cannot set the correct VCF CUTOFF frequency, which should be 16Hz, well actually it is 67Hz, and if I turn the R71 trim more cw, the oscillation disappears.

2) VCF/OCT R68: it won't go beyond 700Hz (it is supposed to be 800Hz).

3) I have to remake a new power supply, because the old one is always fluctuating, and the synth is never tuned.

Beside that, it is a great analog synth from 1974.



And here are the pictures of the new version filter.

Enjoy!

Respect,
Very Happy


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Broadwave



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PostPosted: Sat Nov 01, 2008 2:29 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi 3,

From the looks of things you built the 4034, which was designed for the Pro-Soloist... I'm just wondering if that may be why you're not quite getting the response you expected. Maybe the Pro-Soloists "off-board" components (audio and CV mix and resonance sections) are different from the Oddy.

I'll have a scout round and see if I can come up with anything.

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3nity



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PostPosted: Sat Nov 01, 2008 3:19 am    Post subject: Reply with quote  Mark this post and the followings unread

AndyR1960 wrote:
Hi 3,

From the looks of things you built the 4034, which was designed for the Pro-Soloist... I'm just wondering if that may be why you're not quite getting the response you expected. Maybe the Pro-Soloists "off-board" components (audio and CV mix and resonance sections) are different from the Oddy.

I'll have a scout round and see if I can come up with anything.


Hi Andy,

Thanks for your support !

I am not sure that is a problem linked to the 4034, because even with the original 4075 fitted (the norton amplifier filter) I was experiencing exactly the same issue.

I am more prone to think that some of the old components have come to their life end.

Well, not a big issue, but I would like to understand what might be the cause.

If you have any news, please share with us.

Any successful stories ?

Respect,

Laughing
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Jaba



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PostPosted: Fri Aug 28, 2009 7:51 am    Post subject: Reply with quote  Mark this post and the followings unread

Hello AndyR1960 and all of you,

I am trying to build both your 4023 and 4035 filters, and while checking the PCBs I found something that I don't understand:
in the 4035, chips Z2, Z3 and Z4 (CA3086) all have pins 1, 2 and 3 connected together
but in the ARP schematic I see that:
-in Z2 pins 2 and 3 are linked, but not pin 1, it goes to R5, R6, R7, R17 instead;
-in Z3 pins 1 and 2 are linked, but pin 3 goes instead to Z2 pin 8 and C5; Z3 pins 1 and 2 go to Z2 pin 5 and Z3 pin 13, and to the other end of C5; pins 1 and 2 should go to pin 13 too;
-in Z4 pins 1 and 2 are linked, but pin 3 goes instead to Z3 pin 8 and C4; Z4 pins 1 and 2 go to Z3 pin 11 and Z4 pin 13;
[part numbers are taken from the ARP 4035 schematic, in your PCB Z2 is up left, Z3 up right, Z4 down right]

maybe I am missing something, or referring to the wrong schematic, or ...?

would you please check that the PCB you published is correct ? or else help me find my mistake ?
thank you

another detail: the 220nF input capacitor should actually be two 220nF capacitors in parallel, according to ARP service manuals

thank you for all you are sharing, I am learning a lot here
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Broadwave



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PostPosted: Fri Aug 28, 2009 10:01 am    Post subject: Reply with quote  Mark this post and the followings unread

Jaba wrote:
Hello AndyR1960 and all of you,
maybe I am missing something, or referring to the wrong schematic, or ...?

would you please check that the PCB you published is correct ? or else help me find my mistake ?
thank you

another detail: the 220nF input capacitor should actually be two 220nF capacitors in parallel, according to ARP service manuals


I don't know what schematics you are comparing with (maybe J. Verghese?), in that case, he has drawn the schematics slightly differently from the genuine ARP copies I have - those transistors are not used in the circuit, so ARP just tied the EBC pins together. Don't worry the board works fine - I've built several of them.

The two 220nf caps are used in the later MKIII Odyssey with the 4075 VCF.

It's fine just to use one 220nf for the audio input into the 4023/35

Andy.

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Jaba



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PostPosted: Tue Sep 01, 2009 4:59 am    Post subject: Reply with quote  Mark this post and the followings unread

yes, the schematics I have are from J.Verghese (btw where did you get those "genuine ARP copies" ?)

on another schematic (from Verghese again), some notes about early versions of 4035 actually correspond to your version;
so I am not surprised that your PCBs work fine, but there may be subtle differences

has anyone tried the 40235 board ? it seems it follows the schematics I have

I heard that the 3046 transistor array chip has better Vbe matching than the 3086, is it worth trying ?

once again, thank you for sharing your work with us
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PostPosted: Sun Oct 24, 2010 2:46 pm    Post subject: Reply with quote  Mark this post and the followings unread

I am having problems with using CA3046 instead of CA3086. i dont have any CA3086 at he moment. I hear it sweep but it sounds low in volume and when I modulate it does not sweep like I feel it should. I am using a tl071 instead of the lm301 also.
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