Zombie REC mComp User manual

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μCOMP Diode Compressor
(r1.1) Assembly Guide
www.zombierecaudio.com
[e-mail]
Last Updated: March 13, 2022

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Disclaimer
Zombie REC. is not liable for any damage, harm or loss of any kind resulting from the assembly
and/or use of this kit. Improper soldering and handling of electricity can cause serious injury and
damage to your property. Also, keep all contents away from children. Follow the guide, build
carefully and pay attention when using the necessary tools.
If something is missing or damaged, contact us on [e-mail]. If the part shows signs of
use beyond what was necessary to determine that it was damaged, Zombie REC. reserves the right
not to replace the part. Make sure to interact with the parts only on a properly earthed working
place, including the builder, in order to prevent damage to transistors and/or other parts.

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Tools
You will require:
•A good solder iron, with adjustable temperature recommended
•A clean solder tip with a large enough tip (2mm (ca. 0.78in) width)
•Solder, preferably less than 1mm (0.4in) in diameter
•Good wire cutters to clip the excess leads
•A pair of tweezers
•Kapton tape or clear office tape
•Scissors to cut the tape
•Optional but recommended: Means to ground yourself, like a properly connected ESD
wristband

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Kit Contents
1. 28x Resistor:
6x 47k / 9x 10k / 1x 4.99k / 1x 220k / 1x 61.9k / 1x 2k / 3x 470R / 1x 100R / 1x 6.65k / 2x 13.3k / 1x 1k /
1x 510R
2. 14x Capacitor:
3x 470uF / 1x 1500pF / 1x 1uF / 6x 100nF / 3x 47pF
3. 2x Transformer
4. 7x Hardware:
1x 8pin header / 1x 4pin header / 4x Standoff / 1x Jumper
5. 1x SMD SOT-23
6. 4x Transistors:
2x 2N3906 PNP / 2x BC550 NPN
7. 6x IC Components:
2x TL074 / 1x TL072 / 2x 14Pin DIP Socket / 1x 8Pin DIP Socket
8. 8x Diodes
3x 1N4148 / 5x 1N750A
9. 3x Trimpot:
1x 50k / 1x 100k / 1x 220k
10. 1x PCB (not shown in picture)
This build is a bit more complex and you should plan enough time to build it.
4
5
6
7
8
9
1
2
3

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Step 1 – SMD Part
Well start with the most difficult part first, the SOT-23 surface mount device. It’s D9 on the PCB:
Fetch the part and also prepare the tape, scissors and tweezers. Use the tweezers to get the part out
of the packaging:
Cut some tape as shown below, it should be long enough to be applied by using both of your hands.
Use the scissor to cut it to prevent it from sticking to your finger prematurely. Carefully hold the

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sticky side up with your finger and stick the SMD part with the tweezers bottom up on the tape so
that it’s single foot hangs outside (the bottom is where the legs are flush):

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Now flip the tape with the SMD part on it and apply it like you would with a band-aid: Use both
index finger and thumb on both hands to gently align the legs of the part and simply push down on
the tape once you have it aligned. Make sure that the legs are vertically facing the PCB surface and
not away from it:

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Now solder the pin by gently pushing the tip of the solder iron on the PCB and the pin and apply
some solder:
Remove the tape and solder the remaining two pins the same way:

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Step 2 – Small Ceramic Capacitors
There are 3x 47pF caps to solder: C5, C12, C13 (red) and 6x 100nF: C1, C2, C7, C8, C10, C11 (blue):
We’ll take a closer look now how to properly solder these.

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When you insert them, make sure to firmly push down between their legs to bend them as close and
tight to the PCB as possible:

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Then clip off the first lead while holding the wire cutters parallel to the surface in a way that the
remaining lead «overhangs» the hole onto the PCB and locks the part in place that way:
Then solder the first lead and repeat the process for all the second leads:

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Step 3 – Trimpots
There are 3 trimpots to solder: 1x 50k, 1x 100k and 1x 220k.
The values are marked on the side of the pots. Insert the 50k where it says «Thr», that is the
Threshold control. Insert the 100k where it says «Att», that is the Attack control. And finally insert
the 220k where it says «Rel», that is the Release control.
The pots are conveniently held in place by their leads, but in case its a bit loose, just hold them in
place with some tape. Now solder them. Since the stand-offs are long enough, its not necessary to
trim their excess leads.

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Step 4 – 4 pin Header
We’ll solder the 4 pin header next, as it is most convenient to do it now:
For this, use the tape again to hold it into place for soldering:

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Flip it over and solder away. If the tape is in the way, solder the easy accessible pins first then
remove the tape and do the rest:

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Step 5 – IC Sockets
We also do the sockets right away because it’s most convenient to do it now:
Start with the 14 pin socket at the bottom.

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Make sure to insert the socket so that the notch and the marking on the PCB are aligned. Use tape
again to fix the socket in place. While doing so, make also sure that the socket is flush on the PCB:
Then flip it over and start soldering. You can remove the tape after soldering at least 4 pins, then
finish the rest.

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Then continue with the upper 14 pin socket:
And finish with the 8 pin socket:

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Step 6 – Diodes
There are 8x diodes in total. Start with the 3x 1N4148 diodes. Bend the leads at the tip of the diode
with the black band (cathode) like so (do this for all diodes):
Insert them into D1, D2 and D7. Insert the long lead side without the black band (anode) where the
white ring is on the PCB. The black band side should go into a hole marked with «K». Each diode
should be inside a single «box» that is made up of white corner markings on the PCB (see image
below).
After inserting them. Proceed to secure and solder them the same way we did it with the ceramic
capacitors before. Go back and check out step 2 again if necessary.

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Continue with the remaining 5 diodes. Insert the first diode into D8, and follow up with D3/D5 and
D4/D6. Solder them again as shown previously.