Arp1601

Buildeguide for rev.5 

the most important change to earlier versions:

Changed:

2x LM3046M SMT instead of CA3086 THT (rare part)

1x MC14528 SMT instead of rare THT Version

All Slider Switches changed to other versions.

Panel holes for 3.5mm jacks bigger

lets start:

we start with the SMT Parts:

use 0.3mm or 0.5mm soldercore with lead and a small soldertip, add a small solderpoint at one solderpad on pcb.

doublecheck the IC orientation - check my picture for details.

touch with the solder iron the pad where you added before the soldercore, now is your IC fixed, check the correct allignment between the IC pins to the pads.

solder at the outer pins at beginning followed by the other side, dont give the too much heat, good tutorials are at youtube for SMT soldering or ask me to assist you.

second step, Powersupply 

what you need to know:

you can power the Sequencer without the internal PSU, if you have a Arp2600 or TTSH, you can use the -15V/15V  for the sequencer too, thats why you find a power input (3pin MTA100 close to the DC-DC part) (PL1 on PCB)

internal power:

place and solder (with a big soldertip) the DC-DC adapter on the PCB, solder one middle pin and check the correct placement, sometimes its not close enough on the pcb.

add the L3 (12uH inductor), L1&L2 are ferrite beads., place and solder the 47uF, 2x10uF capacitor and 2x 100nF ceramic disc cap, feel free to add the 3 pin MTA100 header for external input(output)

add the 2 big MTA156 2 pin header on pcb (on left side)  thats for the powerswitch and one for the 12V DC-36V DC Power input (PL1)

for testing you can bridge the PL4 header (switchheader), 

solder all powersupply parts and cut the "part legs/pins " short.

now you can test the powersupply for correct output, it must be measured at the MTA100 power input header (PL1) -15V/15V

only if this voltage is correct, build further steps (around +/- 14.8-15.2V)

Step 3:

Add few spacer on the pcb to have a distance between the desk and pcb

start with the 0.1% resistors and 650R/680R/750R resistors

then:  1K,10K,100K, 22K

followed by all other values, solder from top side one pin, turn the pcb and solder from solderside (thats what i prefer)

Step 4:

add all capacitors and Transistors and solder ..

Step 5: IC sockets and more

add all IC sockets on same pcb side like the resistors, ignore the silkscreen notice about sockets (that means the 6.3mm jacks)

place and solder the 2pin MTA100 (PL2 ) thats the external footswitch input,

remove all spacer and mount the 11mm spacer on the solderside of the pcb.

Step 6:  Sliders

Place the Slider on opposite side of the resistors (you see it on my pictures),

bend few pins to give the slider a temporarily position. 

Step 7: jacks

add 2 jacks at the outer positions in place and solder one pin, that helps us later to fix the frontpanel here, because there's no spacer on this side.

only 2 jacks yet.. more on step 9 later

Step 8: Switches

add all switches and the 3 cherry pushbutton switches, solder only the middlepin on the switches temporarily !

Step 9: more jacks

add all other jacks in the position, DONT solder it yet.

Step 10:  Frontpanel & more

mount the frontpanel, use the 2 jacks to give the panel on the right side a temporarily fix.

now you must carefully check the alignment, hight, positions of all sliders, jacks, switches.

my best practice tip: solder not so much yet, only 1-2 pins per switch than check again the alignment by using of the switch.

Step 11: IC´s

turn the sequencer on a clean flat desk/table and insert all  ICs, double check the orientation.

Step 12: first test

before that: use a jumper at  the 2pin MTA100 (PL2 ) thats the external foot switch input, or the sequencer wont start.

move the Switch to trigger, move the clock speed slider to 10-30%, the FM and PW slider to zero.

turn on the sequencer, the STEP LEDS must be move from step to step . clock LED blinks (if not move the slider) and the FM/PWM slider must be illuminated all the time.

IF NOT, power off the machine, remove power, check IC orientation

Step 13: Calibration

use the original ARP1601 service manual for it.

→>> not

OLD rev.2  buildguide only for reference - thats not the actual guide, but it helps you in case of failure

NOT APPROVED for REV.5  version !

Mod: Clock Frequency (thanks to Ultravox)

source: https://www.muffwiggler.com/forum/viewtopic.php?t=138862&postdays=0&postorder=desc&start=25

I was able to get the Clock Freq slider to work full travel by increasing the resistance of R17 to approx 222.5k. I didn't have a resistor of that value so I put a 100k trimmer in series with R17 and adjusted it so that the clock will still operate when the slider is set to min. The Clock Freq slider now gives 1Hz - 100Hz from min to max travel.

Schematics from rev.1, not compared to rev.5 !  but its 99.9% the same inside.

ARP 1601 Sequencer - Schematic (round 1).pdf

Panel: