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PCB Assembly

Zener Diode

2

6

Previous Steps

Ground Pins

Solder Joints

Components

Zener Diode

PCB A

R7 1G

PCB B

Components List ~

Next, we can focus on diodes and resistors:

Solder the zener diode onto PCB A.
Solder resistor R7 onto PCB B by lifting one of 
the resistor legs towards ground pin G.
Trim any excess with wire cutters after 
soldering.

Double-check the orientation of 
the diode against the PCB 
marking.

Diodes can be sensitive to static 
electricity so make sure you are 
wearing cotton and discharged 
before handling it.
Do not use the through-hole on 
the PCB when lifting the resistor 
leg and solder directly onto the 
isolation turret.

Build Notes ~

Содержание 87 FET Mic Kit

Страница 1: ...Yuzu Audio DIY Audio Electronics Made Easy Build Guide v1 0...

Страница 2: ...ors TantalumCapacitors Film Capacitors Electrolytic Capacitors JFET Transistor Styroflex Capacitors ToggleSwitches Chapter 3 PCB Wiring Chapter 4 Switch Wiring Chapter 5 Transformer Wiring Chapter 6 X...

Страница 3: ...designations but in this kit we have decided to focus on the vintage U87i circuit to retain the original sonic characteristics of the microphone To help you focus on the important parts of DIY audio p...

Страница 4: ...temperature control is necessary to get clean solder joints on this build For PCB work a chisel tip with an iron that can go up to 350 C is preferable Solder The choice of solder can be quite subjecti...

Страница 5: ...before tackling the next steps Using a three band or four band resistor color code chart assess the resistance value of all the components Build Notes 5 First let s start the PCB assembly by soldering...

Страница 6: ...to PCB B by lifting one of the resistor legs towards ground pin G Trim any excess with wire cutters after soldering Double check the orientation of the diode against the PCB marking Diodes can be sens...

Страница 7: ...esistors with a method described on the next page In this step we finish soldering the resistors along with the inductors Solder all the remaining resistors to their corresponding locations Solder ind...

Страница 8: ...owing a reading of 0mV You now have R2 and R4 matched Method You may find that some circuits require resistors to be matched to a high degree of precision In fact the U87 circuit falls into that categ...

Страница 9: ...we will start working on the capacitors starting with the tantalum kind Solder all the tantalum capacitors onto PCB A Trim any excess with wire cutters after soldering Double check the orientation of...

Страница 10: ...ts List It s time for the film capacitors in this step Solder all the film capacitors except for the Styroflex which will be soldered later on Trim any excess with wire cutters after soldering The ori...

Страница 11: ...e care of the electrolytic capacitors Solder all the electrolytic capacitors onto PCB A Trim any excess with wire cutters after soldering Double check the orientation of the capacitors against the PCB...

Страница 12: ...pin GG Solder variable resistor R11 onto PCB A Trim any excess with wire cutters after soldering Double check the orientation of the transistor against the PCB marking You may have to bend the middle...

Страница 13: ...l the Styroflex capacitors One of them will need one of its legs lifted up towards ground pin G Trim any excess with wire cutters after soldering The orientation of the capacitors does not matter here...

Страница 14: ...the toggle switches Solder the 3 way toggle switch onto the PATslot on PCB C and the remaining 2 way toggle switches onto the LC and PAD slots Trim any excess with wire cutters after soldering Clean o...

Страница 15: ...ould collapse nicely between the PCBs facing away from each other when assembled on the microphone body No need to twist the wires here You can choose to solder the wires on the component side or use...

Страница 16: ...C Wire point OMN of PCB B to PAT1 of PCB C CRD to PAT2 and 8 to PAT3 Repeat for the PAD points of PCB B to PAD 1 and PAD 2 of PCB C Repeat for the LC points of PCB B to LC 2 and LC 3 of PCB C Make su...

Страница 17: ...n order to achieve different diaphragm pressures In the case of the U87 however electrical methods are employed by making use of the dual capsule design of the K87 By disabling the rear diaphragm the...

Страница 18: ...ough the PCB holes No need to twist the wires here Double check the polarity of the primaries and secondaries by making sure that the positive terminals p and s connect to the black and yellow wires c...

Страница 19: ...nario where you are unsure as to which wires belong to the primaries or secondaries of your transformer Some may even be wired incorrectly from the factory Therefore checking the resistance on the win...

Страница 20: ...ides of the microphone body by using eight M2 x 4mm screws with PCB A facing the front of the microphone along with the pattern switch Make sure you leave enough length to the wires if trimming any ex...

Страница 21: ...LR and was named the U87i The U87p on the other hand is a small modification on the U87 circuit which provides a slightly lower output level for mic preamps designed for dynamic microphones with quiet...

Страница 22: ...common ground Set the multimeter to the 20V DC range Adjust variable resistor R11 until a reading of 11V is achieved on the voltmeter Calibration Notes You might find that your microphone sounds best...

Страница 23: ...n 2 of an XLR cable to the exposed leg of resistor R6 From the same cable connect the ring of the TRS cable or pin 3 of the XLR cable to the microphone body or any ground point on the PCB Send 48V pha...

Страница 24: ...ty of JFETs can vary considerably and therefore every circuit must be calibrated to each transistor in order to provide the best THD response In our case we are particularly interested in the IDSS Zer...

Страница 25: ...capsule mount holes to the front of PCB B Solder FD to the front diaphragm FBK to the front backplate RD to the rear diaphragm RBK to the rear backplate Build Notes No need to twist the wires here Dou...

Страница 26: ...version in 1986 the capsule was switched to the K67 as used in the famous U67 tube microphone manufactured prior to the U87 The K67 was also a dual diaphragm design but unlike the K87 the backplates...

Страница 27: ...problem you can test for continuity between the backplates of the capsule by using your multimeter in continuity mode There should not be any continuity between the backplates of the K87 capsule Q A...

Страница 28: ...s Dany Bouchard poctop at vintagemicrophonepcbkit com Pei Chung Ting chunger at store studio939 com AMI TABFunkenwerk at tab funkenwerk com Heiserman Audio at heisermanaudio com ShuaiYin Electronics a...

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