Assembly Instructions for EZK Daughterboards - bobxyz version

[bobxyz]

Over the years, there have been various different EZK daughterboards that allow an external EPROM to be used with a Bosch EZ116K Ignition Control Module. The addition of the daughterboard makes the EZK "chippable" for custom tuning. The original Bosch factory daughterboard is usually found in the gold metalized EZK boxes in later 740/940s. Other DIY daughterboards that I know of include ones from blabla, Bijlsma, Classicswede, HarrieCo, and redblockpowered.

Since the supply of these is drying up, I made my own open-source version and have attached all the design files needed by jlcpcb.com (in China) to build and assemble boards if anyone wants to do their own run of boards in the future. Roughly ~$180 for 25 boards, including shipping to USA, customs, tariffs, taxes, and fuel surcharges. Since the EZK firmware only needs 8KB out of the 32KB EPROM, I added DIPswitches to my version of the daughterboard to allow selection between 4 different images or tunes. I also included the option to use an external DIPswitch to select between the 4 tunes without needing to open up the EZK box.

Below are the assembly instructions for the bobxyz version of the EZ116K EPROM Daughterboards, and an example of wiring the bank selects to an external DIPswitch. You'll need to be OK at soldering circuit boards, and at cleaning solder out of the factory PCB holes.

Assembly Instructions
1) Open up the EZK box, remove the circuit board, and find the row of holes for the daughterboard along the back of the PCB. Note that pin location #2 is used as a key and does not have a hole in the main PCB. If you live in a dry climate (e.g. Colorado, especially in the Winter), you should work on an anti-static mat to prevent any accidental damage to the main EZK circuit board.




2) Clean out the solder from the daughterboard holes. I like to use a dental pick and solderwick for this. Heat up the pad until fully melted and insert the dental pick gently - it should pretty much fall into the hole from its own weight with minimal force. Remove the soldering iron, count to 3 for the solder to cool, and remove the pick. Repeat for the rest of the pads.

From the bottom side, clip off any protruding solder and use solderwick to soak up the rest. Repeat pick&solderwick as needed to clean out the holes. The daughterboard pins are a snug fit, so you may need to do a little extra solder removal after trying to install the daughterboard. Instead of the pick&solderwick, you can use a spring-powered solder sucker, but these tend to scatter tiny balls of solder all over the board - inspect the board carefully under a bright light when done.




3) Unlike the other DIY daughterboard versions, there is no way to mis-install my version -- it includes pins for all of the holes, not just the center pins. [Note: if you get your own boards built by jlcpcb.com, you'll need to clip off and remove the 2nd pin from the right (main pcb hole #2).] After soldering the daughterboard onto the main PCB, you'll need to trim the ends of the pins flush.




4) There are 3 DIPswitches on the board, one to enable the external EPROM, and 2 to select the memory bank / tune. The details are:
SW1 - Bank 1 select
SW2 - Bank 0 select
SW3 - Enable External EPROM - if set to Off, the original internal firmware image will be used
Default: Off On On - which selects external bank #3, same as the Bosch daughterboard

SW1 SW2 - Address Range
On On - 0KB-8KB, TunerPro Copy #1
On Off - 8KB-16KB, TunerPro Copy #2
Off On - 16KB-24KB, TunerPro Copy #3
Off Off - 24KB-32KB, Tuner Pro Copy #4

The bank select switches should ONLY be changed when the car is off. If you change them while the engine is running, it may glitch the code and, in the extreme, could cause engine damage.




For better reliability, the daughterboard uses a "machined pin" or "round pin" socket, instead of a cheaper "stamped pin" socket. You may need to bend the EPROM pins inwards slightly to get them all to line up correctly (hold one side of the EPROM against a table and gently rotate/press to bend a whole row of pins at once, repeat for the other row). If available, an extra machined pin socket can be used as an EPROM carrier to reduce the risk of multiple EPROM insertions/removals. Insert the EPROM into the carrier once, then insert/remove the carrier from the daughterboard socket.

The daughterboard includes a 3-pin connector to allow an external bank selection switch to be added - see next post for details.



----------------------------
The full open source design is available at https://oshwlab.com/bobxyz/project_ficxrahr
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For historical info, see: https://www.turbobricks.com/index.p...chematic-and-prototype-need-your-help.383122/
----------------------------
For assembly instructions for other daughterboards, see:
blabla / Bijlsma / classicswede: https://www.swedespeed.com/threads/...oard-kit-function-updated-instruction.221817/
redblockpowered: https://www.redblockpowered.com/harrieco-daughterboard-install
Buchka wasted spark: https://cflomoto.com/pages/buchka-wasted-spark-board-installation-instructions
----------------------------
- Anti-static mats can be found at: https://www.adafruit.com/product/4405 $7.50, or https://www.jameco.com/z/AS13-Velle...Mat-with-Grounding-Cord-30x55-cm_2337895.html $19, or https://www.amazon.com/s?k=anti-static+soldering+mat ~$20+
- Dental picks can be found at: https://www.harborfreight.com/test-probe-set-5-piece-61872.html $4
- Machined pin carrier sockets can be found at: https://www.digikey.com/en/products/detail/adam-tech/ICM-628-1-GT-HT/9832982 $1

 

[bobxyz]

Adding an External Bank Select Switch

Instead of using the on-board DIPswitch to select the EPROM Bank, a 3-pin connector is provided to allow external bank selection. You can use 2 external switches to select between all 4 banks, or just use a single switch to select between 2 banks or tunes. The external bank select signals are protected against electrical noise and static. (Note: the External PROM Enable switch is only available on the internal 3x DIPswitch. It should not be extended due to lack of noise/static protection.)

Below is an example of how to wire up the external bank selects using a small x2 DIPswitch. It's functional, but not very elegant.

The external bank select connector is a standard JST PH series 2.0mm-pitch 3pin connector. Stub harnesses with 30cm flying leads can be found on ebay, which is much easier than trying to crimping the tiny connector pins by hand. The pins are:
Pin 1 - Switch1, Bank Selet 1 (yellow wire)
Pin 2 - Ground (black wire)
Pin 3 - Switch2, Bank Selet 0 (red wire)

The Bank Select address mapping is the same as above for the internal DIPswitches. Note: when using the 2 external bank selects, the internal 2 bank select switches should be set to OFF.

Instructions
1) Drill a 1/4" hole in the EZK box and insert the grommet. I did this in the top lid (points upwards in a 240), but the side of the top lid might give easier access -- you'll need to look at your EZK box location and pick where to drill the hole.




2) Install shrink tube over most of the wires. Leave 1/2" for soldering the external wires to the switches, and ~1" next to the connector for flexibility. Shrink the tubing down all the way. I used a 1/8" rubber grommet (sized for the 1/4" hole), which gives a snug, but not waterproof, fit. If you don't shrink the tubing down completely, it may be difficult to pull through the grommet.




3) Pull the wire bundle through the grommet leaving a little slack for inside the EZK box. Use a zip-tie by the hole to provide some strain relief. Slide the piece of white shrink tubing over the external cable. Solder the 2x DIPswitch, or whatever you're using for switches, to the cable. Yellow goes to one side of Switch 1, Red to Switch 2, and Black to the other side of both switches.




4) Put a zip-tie next to the switch near the end of the shrink tubing. Side the big piece of shrink tubing over the switch and zip-tie. Align the end so that it sticks out just a bit past the switch. Make sure your white shrink tubing is still on the main cable, between the EZK cover and the switch. Now shrink down the big tubing so that it holds the switch and forms around the zip-tie. Slide the white shrink tubing over the tail of the big tubing and shrink it down too.



5) Plug the cable end into the EZK daughterboard, install your favorite EPROM of tunes and check that the internal DIPswitch is set to Off-Off-On. Close up the EZK box while making sure that the cable won't get pinched. Note: these pics show the EPROM (SST 27SF256-70 flash chip) in an extra 28-pin carrier socket - recommended, but you can just plug the EPROM into the daughterboard directly if you're careful and don't plan on changing it often.




The bank select switches should ONLY be changed when the car is off. If you change them while the engine is running, it may glitch the code and, in the extreme, could cause engine damage.

Let me know if you have questions, spot typos, or need sources for the parts shown here.

-Bob

 

[doucheNozzle]

Nicely done

 

[Led]

Here it is installed in a 148 EZK. I traced everything with a continuity tester and everything seems in order.