Rewiring harenss: Flyback/T.S diode? Location of resistor box for LowZ? Grounds?

[uzelac]

Hi

My box was assembled by a friend, it worked for some time, but now i want to do better harness.
Grounds were done way different than it is recommended in various guides including PhatBob's. Beside that, I had some problems with trigger and sensors so decided it will be faster and safer to make new harness than to look for ghosts.

So, three issues for now:

1. I'm kind of confused with wiring, especially with the wire going from one of pins of Motronic connector (i use Bosch box and connector) that is connected to the middle of injectors section of PCB.
I bought just board from webshop, and in the documentation wasn't stated if there was 30V flyback or not. Can someone tell me, by the pictures, is there flyback and TS diode on my board? 



This wire ends on Bosch connector and on the other side is a wire connected directly to +12V.
I presume it is important to state I use lowZ injectors and the PWM is disabled (100%).

2. Four lowZ injectors connected to 4 INJ outputs, and on their supply line there is an resistor box.
One +12V supply coming from the battery is entering resistor box and 4 wires that go out of resistor box are connected to
injectors.
In PhatBob's guide there are separated resistors connected between injetors and INJ contacts on PCB.
Can i leave it this way or should i change position of resistors ?

3. three wires for serial port were wired to 3 pads near Max232 and EC18-pin14 and EC18-pin15 seem not connected.
I presume only assembled VEMS come with usable pins 14 and 15 on EC18, can someone confirm?
Beside, should i use all three pads near MAX232, including GND, or should i solder ground wire of DB9 port to commond sensor ground, EC36-26 ?

There is a link for a picture of whole PCB, if needed:

Bottom:


It is a v3.7 board bought around June 2011 with serial number 3944

Thanks

[jrussell]

Hi

My box was assembled by a friend, it worked for some time, but now i want to do better harness.
Grounds were done way different than it is recommended in various guides including PhatBob's. Beside that, I had some problems with trigger and sensors so decided it will be faster and safer to make new harness than to look for ghosts.

So, three issues for now:

1. I'm kind of confused with wiring, especially with the wire going from one of pins of Motronic connector (i use Bosch box and connector) that is connected to the middle of injectors section of PCB.
I bought just board from webshop, and in the documentation wasn't stated if there was 30V flyback or not. Can someone tell me, by the pictures, is there flyback and TS diode on my board? 

There's no Transient Supression (TS) diode there, commonly the 30V Flyback. It would be in-line with that wire if it were there.

2. Four lowZ injectors connected to 4 INJ outputs, and on their supply line there is an resistor box.
One +12V supply coming from the battery is entering resistor box and 4 wires that go out of resistor box are connected to
injectors.
In PhatBob's guide there are separated resistors connected between injetors and INJ contacts on PCB.
Can i leave it this way or should i change position of resistors ?

I think you'll find, if you investigate further, there are 4 resistors in the resistor box, just packaged nicely. In any case, you can use it like that without problems.

3. three wires for serial port were wired to 3 pads near Max232 and EC18-pin14 and EC18-pin15 seem not connected.
I presume only assembled VEMS come with usable pins 14 and 15 on EC18, can someone confirm?
Beside, should i use all three pads near MAX232, including GND, or should i solder ground wire of DB9 port to commond sensor ground, EC36-26 ?

When you order just a board you don't get all these extras. You're left to do it on your own. You need to connect your own serial wires (well, all of the wires you'll need really).

Hopefully you'll be doing something to heat-sink the power transistors. In our application they are clamped to the case with an insulator sheet so they don't electrically conduct.

[uzelac]

1. I'm kind of confused with wiring, especially with the wire going from one of pins of Motronic connector (i use Bosch box and connector) that is connected to the middle of injectors section of PCB.
I bought just board from webshop, and in the documentation wasn't stated if there was 30V flyback or not. Can someone tell me, by the pictures, is there flyback and TS diode on my board? 

There's no Transient Supression (TS) diode there, commonly the 30V Flyback. It would be in-line with that wire if it were there.

Thanks.
Since it's not there, should I put one ?

I think you'll find, if you investigate further, there are 4 resistors in the resistor box, just packaged nicely. In any case, you can use it like that without problems.

I thought that, but wasn't sure. What's important for me, resistor pack can stay at the supply line, i don't have to move it to lines coming from ECU?
Beside, that flyback wire was going to common supply, no fuses for injectors, so i guess that was OK.
I plan to put fuse, just need to know should i put T.S. diode or not:

Something like this should be final:

When you order just a board you don't get all these extras. You're left to do it on your own. You need to connect your own serial wires (well, all of the wires you'll need really).

Hopefully you'll be doing something to heat-sink the power transistors. In our application they are clamped to the case with an insulator sheet so they don't electrically conduct.

Insulator sheet check, alumininum cooling fins check .

Thanks!

[jrussell]

You absolutely need the TS diode for good injector control. That's why it's in every assembled ECU.

[uzelac]

Will search for one.

I understand i need 1k5e30 or similar.

I can't find exactly the same, would this do the job:
1.5KE33A
UNIDIR TRANSIL, 33V, 1500W, DO-201?

Or 1.5KE30A but it description say lower voltage:
TVS diode
Unipolar, 1500W 25,6V
Case DO201
PDF: http://www.mikroprinc.com/index.php?option=com_virtuemart&Itemid=8&file_id=8599&lang=sr&page=shop.getfile&product_id=7704

Thanks

[uzelac]

One more question.

Wiki on Ground Connections recommends to run separated GND and GND5. What solution is better, to run seperated or to join them near ECU?

Thanks

[rob@vems.co.uk]

It actually says:
"All 4 GND5 (power-ground) pins must be connected to GND (EC36pin26) with short wires max 40cm (1.3 feet) from EC36 connector."

[uzelac]

Yeah, few different information can be found in wiki and guide, but after few days reading, it sounds that all options will be pretty fine, none of them can cause serious problems actually.
Also, I found some other good info in pdf about assembly of VEMS.

Unfortunately, It took some time for me to get that this forum can offer good help for "assembled VEMS" buyers/users, but not that much for "how to assemble VEMS" issues.

Anyway, I soldered all grounds together ~12cm from ECU connector, and "reinforced" GND5 connecting pins 21 and 22 with ground near IGBTs.
Put TS Diode which is specified to 25V, sounded better than 33V since i haven't got 30V one in rescue pack and it can't be found in Serbia.
Added some inputs and outputs, leaved resistor box in place and put some sinks on IGBTs.
Hope it all works, D-Day is Saturday, will let you know what happen. Have I've gone to track or called fire brigade

[jrussell]

Unfortunately, It took some time for me to get that this forum can offer good help for "assembled VEMS" buyers/users, but not that much for "how to assemble VEMS" issues.

I think you'll find that many here have a perfectly good understanding of how to assemble an unassembled unit, but it's a huge drain on support time and effort. Really, people buying unassembled units should have the electronic skill necessary to assemble them. I understand you were putting it in a factory enclosure with a different connector, but it still doesn't change the fact that it's more reasonable to support an assembled and fully tested unit.

This would be the big advantage of purchasing from a reseller.... the direct support available.

Glad you got it sorted though. Hopefully you did get some good pointers here.

[uzelac]

I'm not complaining, just making some conclusions on things i wasn't aware before.
I bugged all of you with questions for which there is no place in this forum.

Only thing I could complain is that all of this is not stated clearly enough on Vems site(s), including webshop.
Or I haven't been reading thoroughly enough

In either case, thanks a lot, you did give me many pointers, I hope I understood them well and this things becomes "assembled" from this weekend .

[uzelac]

TS diode - check
shielded RS232 - check
heatsink for iGBT's - check
more inputs/outputs - check

VEMS is boxed, hope to stay that way.
Thanks for help, once more, couldn't do with out it.