ARP 1601 clone Build Thread

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KSS
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Re: ARP 1601 clone Build Thread

Post by KSS » Thu Feb 13, 2020 6:46 pm

Kipling wrote:
Thu Feb 13, 2020 3:53 pm
I think you've mis-read or misinterpreted my post - "I have stuck to my intention and added six upright side-adjust single-turn trimmers type 3362M"
Yes, please accept my apologies. I should have noticed not only the words but also the screenprint.

Glad to see the 4 pad update! Thank You.

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Kipling
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Re: ARP 1601 clone Build Thread

Post by Kipling » Fri Feb 14, 2020 1:32 pm

Slight amendment, without changing the PCB layout any further from my last post, the recommended *single-turn* gate voltage adjust trimmers is now six-off 652-3362X-1-103LF (single-turn, upright, side-adjust, 10K) which fits the silkscreen outline perfectly and has the staggered pins in the correct orientation and places.

You can if you wish use the common top adjust 652-3362P-1-103LF although the rotation will be reversed (anti-clockwise for full voltage) and will not match the silkscreen outline, or the 652-3362M-1-103LF (in-line pins, upright, side-adjust) which matches the silkscreen but slightly offset and has the correct orientation (clockwise for full voltage).

The multi-turn trimmers are still recommended to be four-off 652-3296Y-1-102LF (1K) and four-off 652-3296Y-1-104LF (100K), although others will fit such as in-line pin variant 652-3296W-1-102LF (1K) and 652-3296W-1-104LF (100K), although the silkscreen outline will be a little offset.

Note: all part numbers are Mouser codes. Drop the '652-' prefix to check stock elsewhere.

You can of course use other manufacturer's similar products. Pretty much anything will fit the pads as long as the ends of the trimmer track are on the two outer pins and the wiper is in the centre (in-line or offset by 0.1") but check the orientation for full voltage once installed. Note: trimmers with a 0.2" wiper offset, such as the Bourns 3362F series or many open-frame trimmers, will not fit.

Hope this all makes sense.

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Re: ARP 1601 clone Build Thread

Post by FactoryDefault » Fri Feb 14, 2020 8:45 pm

elmegil wrote:
Tue Feb 11, 2020 11:31 pm
FactoryDefault wrote:
Tue Feb 11, 2020 11:07 pm
I twisted the 4 outer pins on my switches by 90 degrees. It worked great.
I'm having a hard time picturing what you mean. Photos?

Filing is working, but is time consuming.
Sorry the switches are already soldered and the lid is already on my 1601 but I’ll try to describe my process:

Grip each pin with needle nose with the tip pointing toward the switch. Have the tip of the pliers slightly overlap the shoulder of the pin. Now slowly twist the pliers 90 degrees. This will twist the thick part of the pin into a spiral but won’t break the thin part. The center point of the pin doesn’t shift and the pad inside won’t deform but now the thin part of the pin is sideways you’ll have enough clearance to fit the offset hole pattern.

Btw the switches on the new build feel way better than the ones on my old build. They were kinda notchy and got stuck easily but these are really smooth.

edit: I haven't put the sides on yet so here's a pic of the side of one of the switches:
1601switch-cropped.JPG
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Last edited by FactoryDefault on Sat Feb 15, 2020 12:00 pm, edited 1 time in total.

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elmegil
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Re: ARP 1601 clone Build Thread

Post by elmegil » Fri Feb 14, 2020 9:05 pm

Got it. Thank you :)

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Re: ARP 1601 clone Build Thread

Post by justin3am » Tue Feb 25, 2020 1:08 pm

Finished building this over the weekend.
Image
Just need to finish calibrating but it seems to be mostly working.

Unfortunately the 'Clock Freq' slider doesn't work (LED doesn't light and the slider doesn't change the clock rate) and I'm not sure why. I haven't had time to troubleshoot it yet but the solder joints appear to be good, without any shorts. The Clock FM input does work and I can clock it externally for now. The LED itself works, if I put it in a different fader. I'll have time to troubleshoot over the weekend.

I took notes about my experience with the build and took a lot of pictures. I'll make a more detailed post once I have everything work (and time to get all that stuff together). :tu:
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Re: ARP 1601 clone Build Thread

Post by Kipling » Tue Feb 25, 2020 1:57 pm

justin3am wrote:
Tue Feb 25, 2020 1:08 pm
Unfortunately the 'Clock Freq' slider doesn't work (LED doesn't light and the slider doesn't change the clock rate) and I'm not sure why. I haven't had time to troubleshoot it yet but the solder joints appear to be good, without any shorts. The Clock FM input does work and I can clock it externally for now. The LED itself works, if I put it in a different fader. I'll have time to troubleshoot over the weekend.

I took notes about my experience with the build and took a lot of pictures. I'll make a more detailed post once I have everything work (and time to get all that stuff together). :tu:
My initial thoughts would be that there is a ground problem if neither the slider nor its LED work. The LED and slider track ground connections are on separate pins so check them all. Ground pins can sometimes be hard to solder if the surrounding copper soaks up too much heat, but there are thermal spokes on each one to minimise that chance.

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Re: ARP 1601 clone Build Thread

Post by justin3am » Tue Feb 25, 2020 2:07 pm

Thanks! I'm not worried. I'll poke around with my multi-meter and scope as soon as I have time. It's probably something silly.
I'm super stoked, though. It looks beautiful and all of the controls feel great!. I pre-ordered a Korg/Arp 2600 and I can't wait to use them together!
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Re: ARP 1601 clone Build Thread

Post by elmegil » Tue Feb 25, 2020 2:54 pm

Before you poke too far -- if you haven't calibrated, try calibrating the oscillator frequency first. I found that if R19 was set too low, the oscillator wouldn't oscillate, but turning it up was all I needed.

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Re: ARP 1601 clone Build Thread

Post by justin3am » Wed Feb 26, 2020 10:44 pm

Working 100% now. I'm very embarrassed to admit the cause of the problem. :oops:
I wired the power incorrectly. I had wired the barrel connector to the +15v and 0v of the power output header... I realized my mistake when I discovered that the power switch didn't turn the thing off. :roll:

I'm gonna chock this one up to abundance of enthusiasm and lack of sleep. :lol:

Such a cool sequencer! Very playable. Until now my only experience with the Arp sequencer was from using the Arturia 2600V plug-in. I loved the plug-in but this is orders of magnitude more fun. :goo:

Thanks to everyone involved with the project!
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Re: ARP 1601 clone Build Thread

Post by elmegil » Wed Feb 26, 2020 10:48 pm

Good to hear it was an easy fix!

Everyone pulls at least one thing like this, and some of us several things :)

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Re: ARP 1601 clone Build Thread

Post by Kipling » Thu Feb 27, 2020 3:30 am

Glad it didn’t damage anything. :tu:

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Re: ARP 1601 clone Build Thread

Post by synthcube » Thu Feb 27, 2020 1:25 pm

congrats on a great build and thanks for sharing the details!

here's a few pics of a recently completed 'factory' unit going out to a customer....

1601 v5 4.jpg
1601 v5 5.jpg
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Re: ARP 1601 clone Build Thread

Post by roglok » Thu Feb 27, 2020 3:06 pm

very cool! glad to see that the divider addon made it into production.

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Re: ARP 1601 clone Build Thread

Post by Kipling » Sat Feb 29, 2020 1:23 pm

For anybody with an unbuilt *Rev 3 or earlier* PCB who hasn't purchased the components as yet I have updated the Mouser Project, substituting all the obsolete and soon to be obsolete MLCC caps, and a couple of obsolete resistors - mainly the 100R 0.1% ones for the quantizer chain and a single 10M one.

I have removed any obsolete ICs, namely the 2-off LM3046, 1-off MC14528B and 1-off LM301AN, which must be found in DIP/DIL form from elsewhere.

The link is as before: https://www.mouser.com/ProjectManager/P ... d547f3c361

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Re: ARP 1601 clone Build Thread

Post by solar1 » Sat Feb 29, 2020 3:20 pm

Thank you for the update

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Re: ARP 1601 clone Build Thread

Post by justin3am » Sat Feb 29, 2020 11:23 pm

I posted about the build, with lot of pictures, over here...
https://www.kvraudio.com/forum/viewtopi ... 0&t=540536
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Re: ARP 1601 clone Build Thread

Post by Kipling » Sun Mar 01, 2020 12:54 pm

justin3am wrote:
Sat Feb 29, 2020 11:23 pm
I posted about the build, with lot of pictures, over here...
https://www.kvraudio.com/forum/viewtopi ... 0&t=540536
Many thanks :tu:

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Re: ARP 1601 clone Build Thread

Post by Kipling » Sun Mar 01, 2020 1:10 pm

The Mouser Project for Rev 4 PCBs only can be found here: https://www.mouser.com/ProjectManager/P ... 97dc6d8ca2

For Rev 5 PCB only (created by Jammie) and available from JMSL and latterly SynthCube: https://www.mouser.com/ProjectManager/P ... 605d6af187

And for the forthcoming Rev 6a PCB, available only from SynthCube:
https://www.mouser.com/ProjectManager/P ... d0db4b4d07 Note: SynthCube will no doubt update their existing Rev 5 BOM to Rev 6a accordingly.

The differences are From Rev 4 onwards, the 2-off LM3046 and 1-off MC14528B changed from DIP to SMT; From Rev 5 onwards the slide switches changed from Switchcraft to CW Industries; and from Rev 6a onwards the trimmers have been changed to multi-turn and 6 additional single-turn side-adjust trimmers have been added to lower the gate, clock and Pos 1 out voltages from 14Volts nominal to whatever your equipment requires (0-14V variable) to aid compatibility with eurorack or non-ARP vintage gear etc. and the DC-DC converter has been changed to a much smaller and cheaper Meanwell device, and a 3-pin MTA header has been added for the clock divider designed by @roglok and supplied by SynthCube.

Please note that the Mouser projects do not contain all components necessary to build a 1601 as there are a number of obsolete parts that Mouser no longer supply, such as LM3046 in either DIP or SMT, and MC14528 in DIP (but they do in SMT). Other hardware such as the PJ301BM jack sockets need to be sourced elsewhere. The components required for the clock divider are not included in any of these shared Mouser projects and must be sourced accordingly.

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Re: ARP 1601 clone Build Thread

Post by solar1 » Sun Mar 01, 2020 3:13 pm

Thanks again Kipling for updating and clarifying the parts lists....some of us original, first run builders may build another unit. This will help avoid parts confusion.

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Re: ARP 1601 clone Build Thread

Post by justin3am » Sun Mar 01, 2020 3:28 pm

Thanks for keeping the boys current! I'll be building another one of these soon. Would it be possible to update the first post of this thread with all of the current build documentation?
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Re: ARP 1601 clone Build Thread

Post by Kipling » Sun Mar 01, 2020 4:04 pm

Yes I’ll look at that ASAP. I believe the old forum software limited you to something like 10 attachments per post but that may have changed now.

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Re: ARP 1601 clone Build Thread

Post by checkit » Wed Apr 01, 2020 7:59 am

Hi everyone,

I've just finished building the sequencer and made the first tests. No measurements so far only visual tests.
What is working?

All LEDs in the faders are on, except the LED from the clock fader.
- Reset Pushbutton is working
- Step Puthbutton is working in 16/1 and 8/2 mode
- Sequential/Random pushbutton is working

Now to the things which are not working properly:

In TRIG Mode
a) the LED of the clock fader is shining only a little bit but far less than the LEDs of the other faders. This is true only if the clock fader is at zero. Moving the fader to full the LED shines less and less.
b) Start/Stop pushbutton is working, but the frequency is very fast and cannot be changed with the the clock fader.

Does anyone have an idea where I can look at?

Thanks in advance

Bernhard

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Re: ARP 1601 clone Build Thread

Post by elmegil » Wed Apr 01, 2020 8:41 am

Make sure you go through the calibration steps before you get too worried. I had oscillators that wouldn't go at all until I got the trimmers adjusted.

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Re: ARP 1601 clone Build Thread

Post by KSS » Wed Apr 01, 2020 7:02 pm

For anybody stressing about finding DIP 3046's, don't worry. They consist of five NPN general purpose audio transistors, of which two are matched. It is *very* easy to just use normal NPN's in the PCB holes. Your 16xx won't know the difference. There will be one shared hole at pin 3, and you might want to match the transistors at 123 and 345.

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Re: ARP 1601 clone Build Thread

Post by checkit » Thu Apr 02, 2020 2:33 am

So I started to go through the steps in the Service Manual. Already the first point did not work. When plugging a cable into the CLOCK OUT socket there is nothing to see on the oszilloscope (0 Volt). But what I see looking at the faders is, that now the frequency is changing turning R19 up and down.
So I skipped the calibration steps and looked at the various Testpoints. And there almost everything is working. TP1 to TP5 are ok. At TP6 nothing happens (0 Volt). That was the clock. And moving the PULSE WIDTH fader didn't show any differences. TP7 through TP21 are working as described in the manual....
So any suggestion where I should have to look at?

Thanks in advance

Bernhard

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