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Reverse engineering the Bosch K-Jet ignition module

Started by ptashek, 10 January 2013, 02:56 PM

djenka018

Hey Ptashek,

how about yo make a decent picture (good focus and good lighting) of the front and the back of the original PCB and I can reproduce it.
Please take the close up of capacitors so that a correct type is used (usually 3 letters) and of semicuntductors too.

BTW, the box is stunning.

Vitamin C for SL... the SLC

floyd111


floyd111

That 3D print is amazing.
Out of my comfort zone, I need to ask.. is 3D printing expensive, an item like this?
I take it originality is a bigger issue than 3D printing cost?

I trust you on the STL format.
When I say "we do CNC jobs every week" it really means I am paying 2 or 3 of my Ohlins R&D centers to take care of things.
That doesn't know I know the technicalities as such. I like to surround myself with knowledgeable people so I don't need to memorize every manual that's thrown at me, haha!

ptashek

QuoteThat 3D print is amazing.
Out of my comfort zone, I need to ask.. is 3D printing expensive, an item like this?
I take it originality is a bigger issue than 3D printing cost?

The quality is so-so with the printer I have access to - a 5th gen MakerBot Replicator. Tolerances are the biggest issue. At highest resolution (0.1mm) you get +/- 0.2mm tolerances, and sometimes things don't fit when 3D printed, even though they'd fit perfectly when machined professionally. But it's a superb thing for rapid prototyping, and much cheaper than any other medium I know.

The hardware itself isn't cheap, but running costs are very reasonable - a 1kg roll of PLA filament costs ~45USD, and this entire set of parts used a total of 220g of it, including all rafts and supports. That's just under 10USD, excluding energy costs. The whole thing took ~18h to print (it's a terribly slow process).

Having it all assembled now there's a few small changes I need to make, and then it'll be ready for proper machining.
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE

ptashek

Quote from: djenka018 on 18 September 2015, 07:41 PM
Hey Ptashek,

how about yo make a decent picture (good focus and good lighting) of the front and the back of the original PCB and I can reproduce it.
Please take the close up of capacitors so that a correct type is used (usually 3 letters) and of semicuntductors too.

BTW, the box is stunning.

Parts list: https://s3.amazonaws.com/MB450SE/repairs/w116_im_v5.csv (most of the diodes were impossible to identify, so they're best guesses)

Annotated PCB with track overlay:
https://s3.amazonaws.com/MB450SE/repairs/W116_im_full_annotated.jpg

And here's the same, without the annotations:
https://s3.amazonaws.com/MB450SE/repairs/W116_im_full.jpg

That's the best pics I have of the original board and components. I've replaced all of the diodes with their best guess models, and the box still ran, so did my prototype, so I'm assuming those are correct in terms of value, if not necessarily wattage (albeit both ran fine for 15+ minutes flat out).
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE

djenka018

Vitamin C for SL... the SLC

ptashek

#66
Quote from: djenka018 on 20 September 2015, 07:35 AM
And the size of the pcb?

110mm x 68mm PCB
1.6mm thickness, glass-fibre epoxy, 2oz copper

4.2mm mount drill holes
16mm x 6.5mm center, top side, from PCB edge
16mm x 11.5mm center, connector side, from PCB edge

(78mm x 50mm center to center)

TO3 cutout
45mm from left edge, 18.5mm from top edge to left/top edge of cutout
~20mm across from there.
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE

ptashek

The model is now complete and updated on GitHub.
The only thing I haven't done is the PCB mount platform, but it's a separate part anyway. I'll add it eventually. The box has all it needs.
I've drawn the connector too, pins and all, which should ultimately allow for even that part to be reproduced if needs be.

Next project: cruise control amp! (not)
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE

ptashek

1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE

floyd111

Isn't a refurbished ProgranaInc for 175usd a better idea than a model that's been catching dust, oxidation for 30+ years?

djenka018

Quote from: ptashek on 21 September 2015, 04:41 PM
Well, this is interesting: http://www.amazon.com/Bosch-0227100001-Timing-Module/dp/B006K8XXQY
Brand new OEM box for USD650 straight from Bosch anyone?

Hey,
There's a great saving of $350.

But wait, there's more!

Now you can buy it for only 87 easy payments of 10 bucks only!
That is $10 bucks only!

/not so serious

Vitamin C for SL... the SLC

ptashek

I've just received my eBay module, mentioned earlier. The seller had little idea of what he's selling, I think. This thing is brand new, never used and in original box, made in WK20 of 1982 - for 45EUR, that's a great deal. Connector o-rings have perished from old age, but otherwise it's mint if a bit dirty. Even if it's non-op, I don't care as I can now fix the PCB with my eyes shut.

The value is in all the bits my box was missing due to extreme oxidation.
I didn't even know there's a vent hole in the back of the box, or positioning holes :o
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE

ptashek

I've updated the EagleCAD schematic and board layout on GitHub - there was one net missing, which would have prevented that version to fire. All changes made:

+ Fixed missing net T5.B -> junction R15 <-> R16
+ Renamed C8 <-> C9
+ Replaced D8 with 1N4148 (there's no need for a BYG20 here)
+ Replaced parallel R2 (24k) + R3 (41.2k) with 15.4k R2 only, one less BOM part to worry about
+ Updated PCB layout + routing

I've also made public the model I was working off of when simulating the thing initially:
https://www.circuitlab.com/circuit/5ag5z6/mercedes-benz-w116-ignition-control-circuit/

My prototype survived a 24h burn-in test without a glitch, so I declare this effort done and complete :D
Enjoy, and thanks to everyone who helped along the way. Special thanks to djenka018 for organising the initial schematic properly.
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE

ptashek

#73
-- disregard --
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE

UTn_boy

I'm just catching wind of this amazing thread. Congratulations, PTASHEK!  :) 

Back in September, Stan mentioned that a rebuilt Programma unit may be better than a NOS one.  While the Electrolytics may need replaced in a NOS unit, the Programma units have a very high failure rate.  I don't recommend them. 
1966 250se coupe`,black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3,papyrus white/dark red leather
1975 450se, pine green metallic/green leather
1973 300sel 4.5,silver blue metallic/blue leather
1979 450sel 516 red/bamboo