Building the FUtracer

NOTE: This page has been updated with instructions for building the new version 7.0 FUtracer.
Click here to build the old v6.9 FUtracer.

While building the FUtracer takes high-quality soldering skills, it’s a fairly straightforward process. Install the SMT components first, and thoroughly inspect them (preferably with a digital microscope) prior to proceeding with the rest of the through-hole components. I use solder paste and hot air to install the SMT stuff on my builds. I’ve had great success with this method, but it’s important to inspect your work thoroughly to avoid possibly melting capacitors and things if you need to correct something later. I probably don’t need to tell you how I know that.

The FUtracer PCB Set

Getting Started

Schematics

If you’ve purchased your FUtracer set, then you likely already received the password to view the schematics page. For the main PCB, it’s not really necessary to look at, but it’s usually a good idea to look at schematics. For the socket board, and EXT PSU board, you may need to view the schematics for component values.

Start by thoroughly cleaning and inspecting your PCB set. They should already be clean, but a little extra cleaning is generally a good idea.

SMT Components

For the v7.0 FUtracer main PCB, the tiny SMT work has already been done. All that remains for SMT is the large inductors on the main PCB and PSU PCB, and the not-too-difficult SMT work on the socket board.

For SMT work, I use an Andonstar AD208 digital microscope. It does a pretty darn good job. No lag issues if you don’t max the resolution. If you have a higher budget or a fancier microscope, cool! Either way, I highly recommend something better than a big magnifying glass. Though I do love the cartoonish idea of giant eyeballs inspecting PCBs.

My soldering station is an Aoyue 2703A+ (I’ve been abusing this one for over 4 years- the last 3 stations I had from other brands didn’t last that long). The hot air works great for the SMT stuff. I use Kester EP256 solder paste – it works well but sometimes is a pain in the ass to stick at first.

Through-Hole Components

As with almost any build, you’ll want to start with smaller components, and work your way up in size until you finish with the largest electrolytic capacitors. For whatever reason, I install the DIP sockets first. I suppose it makes it easier to lay the PCB down, and make sure the diodes are placed safely. Then I install all diodes; then small resistors; then larger resistors; then the film capacitors and small electrolytics; followed by the chips; and finally the large electrolytics. It’s all fairly straight forward. Note in the photos below the placement of the ceramic spacers.

Note: There are stock issues on lots of parts, but it’s okay to use equivalent parts in some cases (as long as they’re actually equivalent). For example:
ZTX458 = KSP44;
ZTX558 = KSP94;
BC559 = BC558 or BC327.

Note 2: R101 is 4.7K. R101 and 4.7K are a little close together, so it kinda sorta looks like it says R1014.7K. That’s one of the two vertical resistors next to the USB port. Space was a bit toight.

Your final PCB should look something like this:

The FUtracer Main PCB Fully Built

Chip Orientation

It’s important to make sure your chips are all facing the right way before soldering or powering on your FUtracer. Refer to the following photos for the radial chips, and note the orientation for the socket chips in the image above. Double check! Twice! If you’re not sure, please ask. I’m happy to help, and I will update this site with any common questions.

futracer chip orientation
futracer chip orientation
futracer chip orientation

Safer Current Levels

NOTE: the IaRsense (R45) and IsRsense (R20) resistors by default allow the FUtracer to go to higher currents than what is considered safe for the KSA1156YS. If you wish to play it safer (which is not a bad idea), use 6.8 ohm resistors instead, which will give you a maximum current limit of about 529mA.

If you wish to be even safer and go below the “on paper” limit of the KSA1156YS, you could instead use 7.5 ohm resistors to get under 500mA. Whatever value you choose to go with, it is essential that you enter this value correctly in the GUI options, or your current readings will not be accurate.

The External PSU Connection PCB

The FUtracer is designed to work with a 20V laptop power supply. The PSU PCB is really straight forward. The main PSU I’m using is this 20V laptop style supply: https://www.amazon.com/dp/B07RDPQ2GW/ – I clipped the end off of that and swapped it with a standard barrel plug, and covered it with some heat shrink for my tester. I don’t get a commission from that link, so get whatever you want. Though that one is inexpensive and has worked very well for me. There are three connection points on the PSU. 1 is for an external switch, and the other 2 are 20V DC outputs. One is for the main PCB, and the other is for your heater PSU (see below).

Tube Socket PCB

futracer socket board bottom

NOTE: There is a 1K resistor (R6) on the socket board connected to the Screen. Only install this if you’re having trouble with parasitic oscillations. Use a jumper here instead (pictured).

futracer socket board top

Above is the board I used to test the new PCBs. Normally, I wouldn’t solder the tube sockets completely in until mounting them to the front panel. I suggest that you solder in the tube sockets after dry-fitting/mounting the socket board to your enclosure. If you opt to run wires instead of using PC-mount sockets, be very careful to keep them as short as possible. Crossing the wrong wires could potentially cause issues.

Socket Board Connection

For your connection between the main PCB and the tube socket board PCB, I recommend placing a ferrite bead on the Anode wire and wrapping it through like this:

Socket board connection wires

The Heater PSU

It’s important to note that there is no heater power supply built in to the PCB. You must use an external PSU. This is what I use for the heater power supply: https://www.amazon.com/dp/B01LWXAC5E. I’ve been using that for a few years, and it works great. I’m sure there are other similar supplies that would also work well. I limit the current to 2A in my presets, and you should be sure to limit the current to whatever fuse rating you use on your Socket Board PCB. Click here for the instructions for the PSU linked above.

FUtracer BOMs

Assuming these don’t get hacked, they should be fairly accurate as to what you need. The main PCB has a couple different options for a couple parts. For example, the BAT86S is EoL, so there is a second option available. However, there is plenty of stock of them, so they were not removed from the list yet. I highly recommend buying more than what’s required. Many of the parts have better pricing over a certain quantity, and it doesn’t hurt to have extras.

Main PCB v7 BOM

External PSU PCB

SMT Tube Socket Board

Please Note: There are a number of items including tube sockets, general hardware, etc. that are not included in the BOMs. I use Belton Micalex PC Mount Tube Sockets. You can use those, or find another product with similar pin spacing.

Enclosures

Use a metal enclosure that can act as a ground and shield. Here is an Enclosure Option (will need some modification depending on your layout). If you use a painted or powder-coated enclosure, you will need to sand down the finish where the ground and shield screws mount. Failure to do so could be dangerous and/or prevent the device from functioning.

For anybody interested in a custom enclosure, I have small batch being made specifically for this project. I’ll post photos after I build one in a few weeks.

Schematics

For now, schematics are not public. If you need a schematic, and you’ve already purchased your FUtracer PCB set, you can email support at futracer dot com to request the schematics password to access the pages linked above.

Parts Drawings

Here’s a few drawings for some of the off-PCB parts. You don’t have to use these parts specifically, but if you’re going to PC-mount the sockets, you will need them to be similar dimensions to the Belton sockets.

Belton Noval Socket

Belton Octal Socket (Note: I had to order these from the UK, I couldn’t find a US supplier. Other Belton PC pin sockets will fit, but you might need to remove the mounting ring if you don’t want to use it.)

Power Switch

Power Jack – this drops in directly to the external PSU PCB. If you want to use something else, make sure it matches.