[BUILD] CAPI FC526~500 Series~FET Limiter Kit~Official Support Thread

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jsteiger

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Since the kits have started shipping, it's time for the support thread!  :)

**This is a semi complicated build. It is very important to read completely thru the Assembly Aid before starting on anything. There are some points made in the doc that can save you much time and prevent crucial errors during the build.

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September 21st, 2015 Update:
All support docs for this project can be found on the recently added
Support Docs page at www.capi-gear.com
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RV7 must be jumpered for an FC526 XFMR comp to work.

https://groupdiy.com/index.php?topic=59050.msg911575#msg911575
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Having trouble with the meter cal? Maybe this will help http://groupdiy.com/index.php?topic=59050.msg785426#msg785426

Using a DAW to set up your FC526? Maybe this will help https://groupdiy.com/index.php?topic=59050.msg951386#msg951386

Some details can be found here http://capi-gear.com/catalog/product_info.php?cPath=22_117_190&products_id=432

temp-FC526.jpg


Cheers, Jeff
 

chunger

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building the do-hicky.  Please stand by. . .

Sorry everyone for the extended delays.  I know Jeff really wanted full documentation up for this project much sooner.

Let's get started.  The kit should arrive with the following component packages.

p1285637303-4.jpg


Begin by assembling the main PCB.  Locate the main PCB and the bag with main PCB components.

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Locate the bag with knobs, switches, and hardware.

p1285641175-4.jpg


And retrieve the Milmax sockets for the 3 discrete op-amps.

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Turn the board upside down and place all of these sockets from the back side.

p1285643745-4.jpg


Set soldering iron temperature a bit higher than normal because these pins take a bit to heat up.  I elevated one side of the PCB so the pins all end up resting consistently on one side before the solder cools.

p1285646267-4.jpg


Aim to have a nice fillet of solder flow onto the front side of the board so the pins have a strong mechanical connection.

p1285648233-4.jpg


Next, locate the Milmax pins from one of your un-assembled DOA kits and insert and remove it from each of the sockets.  When the sockets are new, they can be very stiff the first time a pin is inserted, so it is much easier to deal with them one at a time without critical components surrounding them.  This will make installing the DOA much easier when the compressor is fully assembled.

p1285650137-4.jpg


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Use a multimeter to confirm all resistor values and sort them before installing.

p1285654771-4.jpg


I use a piece of regular white paper to lay out the components and cross-reference with the BOM file from the 1st post.

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Carefully bend each resistor and place them into the PCB.

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As a way of double checking my component placement and my parts sorting paper, I do not solder the resistors until all of them have been placed.  This way, if a mistake is made, it is very easy to correct.

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Bend all of the leads outwards to secure them to the PCB and flip the board over.

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Solder the resistors into place, and trim the leads tight to the PCB.

p1285683601-4.jpg


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And, here is the main board with all of the resistors installed.

p1285773775-4.jpg


Next, locate the bag with the diodes and transistors.

p1285740235-4.jpg


Sort all of these components referencing the BOM.

p1285777008-4.jpg


Some of the markings are quite small, but it is important to accurately identify each one.

IN914 are marked:

91
4B

p1285778149-4.jpg


IN5243B Zener is marked

24
3B

p1285778319-4.jpg


BZX79C4V3 is marked:

9C
4V3

p1285778461-4.jpg


Diodes have polarity.  Make sure the end of the component that has the strip locates in the same direction as the silk-screened arrow on the PCB.

p1285791367-4.jpg


Place all of the diodes and double check that the polarity is correct on all of them before soldering.

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Trim the leads flush to the PCB.

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Next, install CR1 to complete the component bag.

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Next, locate the bag containing the capacitors and sort them.

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Start installing the capacitors on the "right" side of the sorting sheet until you reach the 6.8uF capacitors (C2, C3).

The tantalum capacitors have polarity.  Note the "+" marking screen printed on the body.

p1286016221-4.jpg


Make sure the correct leg is inserted into the pad with the "+" symbol screen printed on the PCB.

p1286016471-4.jpg


Here, we have all of the capacitors sorted on the "right" side of the sheet installed.

p1286020237-4.jpg



 

chunger

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At this point, I jumped to the transistors, opamps, relays, and trimmers bag.  The only reason I did this is to populate the board components from "shortest to tallest".

p1286189975-6.jpg


The opamps can sometimes be tricky to orient correctly.  For the TL084, note the notch on one side of the housing.

p1286191049-4.jpg


This will orient to the notch indicated on the screen printing as well as the side with pin 1 (the square solder pad).

p1286191386-4.jpg


On the TL081, the circle on the housing indicates the pin 1 position.

p1286194769-4.jpg


Make sure the circle is positioned at the square solder lug on the PCB.

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Here, both opamps are installed in the proper orientation.

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Next, install the relays making sure the line mark on the component orients to the silk-screened line on the PCB.

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The trimmer values can be confirmed with a multimeter by probing the outer leads.

p1286200507-4.jpg


Note, RV1 has the trimmer dial oriented towards the outside of the PCB.

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After all the trimmers are installed, the board should look like this.

p1286312741-4.jpg


Backtrack now a little bit to the remaining electrolytic capacitors.  These parts have polarity, so it is important to get the + and - sides correct.  For the radial capacitors, the lead with the large stripe is "-".

p1286314451-4.jpg


Also, the longer lead corresponds to the "+" side.

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Make sure these correspond to the silk screening on the PCB.  Also, the "+" solder pad is square.

p1286315327-4.jpg


C36 and C38 are bi-polar, so they do not have polarity even though the casing looks like a normal electrolytic capacitor.

p1286315957-4.jpg


These blue axial capacitors have an "arrow" line pointing towards the negative lead.

p1286316382-4.jpg


This is how they should orient on the PCB.  The arrows point towards the negative terminal.

p1286316871-4.jpg


For C13, the black stripe indicates the negative side, and it should orient like this.

p1286343598-4.jpg


And now, all of the capacitors are populated.

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Next, bend a thick lead cut-off with a screwdriver.

p1286347437-4.jpg


And install for a ground test point.

p1286347792-4.jpg


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In the knobs, switches, and hardware bag, locate the cable header and install.

p1286348557-4.jpg


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It only goes in one way due to the plastic locating pins.

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Next, locate the pots and grayhill switch.  The pots can be tested with a multimeter on the outer 2 pins just like the smaller trimmer pots installed earlier.

p1286354328-6.jpg


Be careful to solder the grayhill switch pins carefully and double check that there are no solder bridges between the pins as they are quite close together.

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One last resistor to install.

p1286362401-4.jpg


Insert at this point and carefully solder

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p1286363684-4.jpg



It is not explicitly stated that this project requires cleaning of the solder flux, but I personally like to keep my builds clean.  Please note, if you decide to clean the PCB of solder residue, go all the way and thoroughly clean it.  There is no half-way option.  It would just leave a sticky mess all over the board.  Use 90% isopropyl alcohol as 70% does not nearly work as well to dissolve the flux residue.  Mechanical scrubbing is necessary.  I use an old toothbrush.  If using a small plate of alcohol like I did here, you will need to change the solution because flux gets dissolved into it and after a while, more scrubbing with the same solution just spreads the muck around.

p1286361409-4.jpg


p1286383715-4.jpg


The result should be a nice, clean board with no residue.

p1286385165-4.jpg
 

chunger

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With the main PCB cleaned up, locat the mounting hardware for the transformer.

p1286387487-4.jpg


We need 2 long screws and 4 lock washers.

p1286388426-4.jpg


And of course a transformer.

p1286388541-4.jpg


We want to have lock washers directly contacting both sides of the PCB.  Start by inserting the screws directly into the top of the transformer.

p1286388865-4.jpg


Flip the assembly over, and place lock washers on the bottom side of the transformer.

p1286389859-4.jpg


Place the PCB on the transformer.

p1286593931-4.jpg


Place 2 lock washers on the back side of the PCB.

p1286595185-4.jpg


And install the nuts finger tight.

p1286598846-4.jpg


After aligning the transformer to the screen printing, snug down the screws from the top side with a screwdriver to lock it into position.

p1286599707-4.jpg


Carefully trim, tin, and install the transformer wire leads to the PCB.  Too long, and they look messy, too short, and well, they won't reach.  Cut a little bit at a time to get the correctly length a little bit at a time.

p1286600919-4.jpg


p1286601487-4.jpg


After tinning, solder the wires from the back side of the PCB.

p1286602139-4.jpg


Clean the solder flux from the new solder connections being careful to avoid spilling alcohol on the transformer.

p1286638771-4.jpg


p1286640164-4.jpg


The main PCB is now assembled.

p1286641116-4.jpg


p1286642483-4.jpg


p1286643529-4.jpg


p1286644572-4.jpg
 

chunger

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Next locate the meter PCB and the bag containing the components to populate it.

p1455059357-4.jpg


p1455058287-4.jpg


Carefully sort and identify all of the components and cross reference with the BOM document.

p1455058935-6.jpg


First, populate the resistors.

p1455059703-4.jpg


p1455060431-4.jpg


p1455061325-4.jpg


Next, locate the main PCB mounting hardware.  We will fit the PCB's to the L-bracket before soldering in the switches and LED's to the meter PCB.

p1455060817-4.jpg


Install the four flat head screws and standoffs to the L-bracket.

p1455061817-4.jpg


p1455062143-4.jpg


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Set the L-bracket aside and locate this long standoff, nut, and lock washer.

p1455062637-4.jpg


Install the lock washer between the PCB and the long standoff.

p1455062981-4.jpg


And position the standoff here on the PCB.

p1455063407-4.jpg


Secure the standoff on the back side of the PCB with the nut.

p1455063801-4.jpg


Slide the main PCB into the L-bracket.

p1455064281-4.jpg


Confirm that all of the pots, switches, and trimmers are aligned with the L-bracket.

p1455064567-6.jpg


Center the main board on the L-bracket.

p1455064793-4.jpg


Attach the faceplate and install the rotary switch and pot knobs finger tight for fitting.

p1455064997-4.jpg


 

chunger

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Next, locate the remaining 2 long standoffs for the meter board.

p1455065146-4.jpg


Install the first standoff making sure to use a lock washer.

p1455065215-4.jpg


And the second one in the same manner.

p1455065386-4.jpg


Next, secure the rear of the PCB with the remaining screws and split lock washers.

p1455065531-4.jpg


Next, locate these 3 toggle switches for the meter board.

p1455066047-4.jpg


And set them in place on the front side of the meter board.  For my installation, the switches held in place at this time via friction fit, so I will not solder them yet until I have the meter board secured in final position so all of the switches will be guaranteed to align perfectly.

p1455066325-4.jpg


Next, I begin placing the meter LED's making sure to heed the polarity of the LED's.  Note, the short solder pads correspond to the shorter lead on the LED units.  In this step, I deviated from the build documentation that recommends cutting the LED leads to length before placing on the board.  My main reason is I wanted to be extra careful not to make a mistake on the polarity of the LED's and I trust my finesse with wire cutters after soldering.

p1455066605-4.jpg


Placing all of the components first without trimming them to length allows me to visually confirm polarity with all of the LED's in position.

p1455066833-4.jpg


Next, place the meter board into final position and align all of the components to the front plate.

p1455066980-4.jpg


Locate the following hardware to secure the meter board.

p1455067329-4.jpg


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Place a piece of console tape on the front plate to help hold the LED's in place for soldering.

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And press all of the LED's firmly to the tape and re-verify polarity and colors.

p1455068043-4.jpg


With all of the LED's in final position and verified correctly oriented, solder the exposed pads.

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Next, with the switches in final alignment against the front plate, we can solder them in place.

p1455068503-4.jpg


Carefully cut the excess LED leads at this time and visually confirm that the solder connections are clean and only touch the correct solder pads.

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Next, remove the switch PCB from the main assembly, turn it over to the back side, and solder the remaining LED leads.

p1455069330-4.jpg


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Carefully trim the back side LED leads in the same manner as the front and confirm there are no shorts beyond the designated pads for each connection.

p1455069838-4.jpg


With these components in place, now is a good time to clean the board with isopropyl alcohol.

p1455070011-4.jpg


Next, install the ceramic capacitors.

p1619698238-4.jpg


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And the IC's making sure the notch in the chip corresponds to the notch in the silk screening on the PCB.

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Next, populate the film capacitor.

p1723886902-4.jpg


Install the electrolytic capacitors making sure the confirm the correct polarity.  The longer lead is + and the printed white stripe on the can is -.

p1705212492-4.jpg


Populate the cable connector.

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. . .and CR1 diode and Q1 transistor.

p1737991982-4.jpg


With that, the meter PCB is fully populated.

p1725882566-4.jpg


If you are opting to clean the boards, scrub the flux off with isopropyl alcohol.

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Nice and clean.

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Next, locate the ribbon cable.

p1770087386-4.jpg


And install one end to the meter PCB.  Note the location of the red wire in the ribbon cable.  This corresponds to pin 1.

p1856103973-4.jpg


Re-install the fully populated meter PCB.

p1816320190-4.jpg


And connect the other end of the ribbon cable to the main PCB.

p1852261517-4.jpg


With the electronic components fully populated and the PCB's cleaned, refer back to the sorting sheet where we placed the information for our F3 and F4 FET's.

p1780314362-5.jpg


Copy this information to the designated white areas on the main PCB with a permanent marker.

p1718067769-4.jpg


Use console tape placed on top of socket wrench to install the knob nuts. 

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And set the knobs with an allen key.

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Next, locate the colored inserts for the knobs. . .

p1628935204-4.jpg


. . . and install them into the knob centers.

p1648372765-4.jpg


With that, final assembly is complete.

p1736176431-4.jpg


 

chunger

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Next, we will run through the initial verification steps outlined in the build guide.

First connect the ground lead of a multimeter to this lug.

p1737621739-4.jpg


And confirm that the resistance to the "-V" DOA sockets is more than 500 ohm.  This is confirm there are no direct shorts.  Mine registers 2.6K.

p1690625052-6.jpg


Next, connect a power supply to the unit.  Here, I am using my "plug in" adaptation of a JLM powerstation.

p1830743503-4.jpg


Apply power to the unit and confirm no smoke! 

Then, confirm the "V+" and "V-" sockets for the DOA's are correct.

p1732187825-4.jpg


p1875272954-4.jpg


On Jeff's recommendation based on field testing by various studios, I will be using GAR1731 op amps all around on this build.

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Place the 3 opamps into their sockets.

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And this completes the build phase of the compressor.

Humans Win!

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jsteiger

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Winetree said:
Sonically would there be a difference running
I.C. opamps in the Receiver and VVR Signal Preamp positions vs. discrete opamps?
Yes, they all add up and make a noticeable difference. While its not huge, it is definitely there. I'm very interested to see what you and Tony think. I imagine you guys will do some extensive listening  ;)
 

jsteiger

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fragletrollet said:
so.... who won the compressor in the end?  8)
Lolo from RealGear. He's in Australia. He's having our buddy Joel Phillips from Nashville build it for him.
 

jswagler55

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I'm going through the build and on the Meter BOM it says that C1 is one of the 33μf, 35V Radial Capacitors. On the actual PCB it looks like C1 should be the .47μF, 63V Metallized Polyester Cap that is currently labeled C3 in the BOM.
 

jsteiger

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jswagler55 said:
I'm going through the build and on the Meter BOM it says that C1 is one of the 33μf, 35V Radial Capacitors. On the actual PCB it looks like C1 should be the .47μF, 63V Metallized Polyester Cap that is currently labeled C3 in the BOM.
Good catch! There is always something. I have made the correction and uploaded the new file. Hopefully that was the only one  ;)
 

jsteiger

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Winetree said:
Jeff,
I know the sockets are not included in the kit,
but would it be a good idea to socket the I.C.s and transistors or not?
I thought about it but did not really see a need for it Robert.
 

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