This page is the checklist for GenBoard/VerThree with stepper driver chip
[SN754410NE stepper driver chip available here]
- the stepper driver chip is the only throughole chip on the board. It's called powerdip footprint: the 2x2 middle pins (GND5) are used for cooling. The SN754410NE chip is mounted in natural orientation, the notch is away from EC18. If you don't have this chip, the rest of the checklist is not interesting (but the stepper lines will not be activated of course)
- 10uF (1210 size, 35V) capacitor is recommended under the stepper chip, on the bottom side (see GenBoard/VerThree/RescueKit, namely rescue2 envelope for the cap)
D45 options - OBSOLETE (since v3.3 stepper driver supply is connected with direct trace).
The "D45 southern pad" (referred below) is at the board-edge, 70mm from the left side. This goes to the 12V supply pin of the stepper-driver chip.
EC36-pin25 (corner pin of EC36, closest to the PCB edge, and closest the EC18) is the 12V mains supply. The advantage of using this pin (below) instead of the "northern pad of D45" is that the stepper current is drawn directly from the EC36 supply pin, and not going through the small fuse. Therefore the small fuse can be really small (eg. 450mA) providing really effective protection.
Chose one of the 3 according to your taste:
- wire from EC36-pin25 to southern pad of D45 - if the wire is not a fuse (not the weakest link, thus never blown), reverse diode (detailed in next option) is not needed.
- fuse and reverse diode - this is the most sophisticated option:
- 2..5A fuse (2A limit is enough normally, as bipolar stepper never draws same direction current from all 4 channels) from EC36-pin25 to "D45 southern pad". This can be a thin wire, acting like a fuse (if you know how thin it should be). Practically, apply this at the bottom of the board. Solder it after (or at the same time as) the diode (below), practically to the diode pads.
- 1n4007 diode: cathode (- mark) at EC36-pin25, anode at "D45 southern pad". Practically, apply this at the bottom of the board. This is effectively a flyback diode, provides some protection should the above fuse be blown.
- wire in place of D45 - works fine if the F1 fuse is powerful enough not to be blown from the stepper current. Note that with this wire it does not matter if there is a diode in D45 pads (with any orientation). A wire parallel with the diode (shorting the diode pads) makes the diode redundant. Leave this if you already have it, but choose one of the above for new installs.
A: D45 is on the bottom side, between ec18 and ec36 below the F1 on the top side. - DB
TODO: picture
Burned stepper chip Question
Q: I have connected a vems to an Audi 1.8T car.
- I want to use it with [ICM delete]
- But i have connected it (it== what exactly? What type of ignition coils?) to stepper ignition outputs which is in EC18plug instead of EC36 - 34,36,24,10 pins.
- There is a chip called sn754410ne burned.
- in these situation will it burn only sn754410ne?
- With some luck, only the sn754410ne is burned. In unlucky situations some other chips can be burned as well.
If it is belongs to stepper, can i use the ecu via removing this chip, when using 34,36,24,10 pins?
Make sure the EC36/34,36,24,10 (or whatever used) pins match the ignition transformers, (IGBT or logiclevel) for YOUR controller (depends on options you purchased with), check [assembled controller webshop product page] that actually points to GenBoard/Manual/IgnitionOutput
Some experts on ChatViaIrc were trying to find out what's happening with your install, but totally uncertain of what ignition coils you have. Apparently [ICM delete] means using logiclevel outputs with logiclevel coils instead of the factory "Power output stage" + power-input coils.
But how did the logiclevel coils burn the stepper chip ? Assumedly power-input coils were used (that explains why stepper outputs got burned). Check the type of coil. To be sure please also measure resistance of coil pins (all combinations). If you find 2 pins (other than multiple-grounds) that have appr 0.3 Ohm between them (often same in both directions), than it's not a logiclevel ignition coil.
'''*** This customer gutted an Ignition Control Module (ICM) and soldered direct wires inside to bridge the gap.
- The problem is the adapter harness he made was connected to the Stepper Outputs (which is only intended to drive the ICM.
- He was supposed to re-pin the ignition outputs to EC36 Pins 34,36,24,10 for IGBT outputs.
- So, the Stepper driver was forced to attempt to drive old 3 wire Audi "AEB" COP coils directly, causing 7-8 amps of load to Stepper chip.
- He is asking if his ecu will be OK if the Stepper chip is removed. I answered (we will have to see, possible ship to HU for repair)