Author Topic: Reverse engineering the Bosch K-Jet ignition module  (Read 23198 times)

ptashek

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Re: Reverse engineering the Bosch K-Jet ignition module
« Reply #75 on: 29 March 2016, 05:15 AM »
[..] the Programma units have a very high failure rate.  I don't recommend them. [..]

Interesting. They do have a good reputation on the cruise control amp front.

Considering my badly soldered prototype sailed through 24h of red-line conditions (simulating ~5000km driven at top-speed), I'm a little surprised a professionally rebuilt unit would fail. There's very little that can fail here, so it's either due to low quality component, issues with heat dissipation or bad workmanship - or maybe all three. I'd love to see inside an ignition module rebuilt by them, and see what it is they're doing in there.

Anyone got a failed unit, or a working unit that's past warranty and could be opened up and photographed?
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UTn_boy

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Re: Reverse engineering the Bosch K-Jet ignition module
« Reply #76 on: 30 March 2016, 03:54 AM »
I agree about the cruise control units they supply.  I've never had a problem with any of those. 

Regarding the ignition control modules, I don't know what they do, replace, or "re-do" in the ignition module. If I come across a Programma unit that is faulty, it's yours. 
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elias

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Re: Reverse engineering the Bosch K-Jet ignition module
« Reply #77 on: 01 November 2021, 04:13 AM »
Dear,

i have an 280SEL,  ignition unit  ,  bosch 0 227 051 014,  for a 6 cyl.
there is 1 component on the circuit board that i can't determine,
could you help we with  that component.  it's a black big round ball .  2 pc are on the board.
i put a red circle on it.
i'n my electronic drawing i named them X1 and X2.


UTn_boy

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Re: Reverse engineering the Bosch K-Jet ignition module
« Reply #78 on: 01 November 2021, 09:35 AM »
That's a very early W116 unit.  Those black items would have to be a capacitor or some type of diode.....Zener, Schottky, etc. 
1966 250se coupe`, black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3, papyrus white/dark red leather
1971 280sel Black/black leather
1973 300sel 4.5, silver blue metallic/blue leather
1976 280s astral silver/blue MB Tex

ptashek

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Re: Reverse engineering the Bosch K-Jet ignition module
« Reply #79 on: 01 November 2021, 07:35 PM »
They're most likely standard rectifier diodes, like a 1N4004.
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE (history, resto)

elias

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Re: Reverse engineering the Bosch K-Jet ignition module
« Reply #80 on: 05 November 2021, 08:58 AM »
hi,

thanks  for the feedback,
there is some kind of very thick coating on it which i didn't notice the first time,  and if you use my sharp probes to measure now in diode mode ,  i see a drop of 0.456 V
certainley a diode.  like you suggested.  thx.

in the centre of the board you have the transistor,  would you know which type this would be , or which type is used in the drawing of the 0227100001b that you made.

ptashek

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Re: Reverse engineering the Bosch K-Jet ignition module
« Reply #81 on: 05 November 2021, 02:15 PM »
hi,

thanks  for the feedback,
there is some kind of very thick coating on it which i didn't notice the first time,  and if you use my sharp probes to measure now in diode mode ,  i see a drop of 0.456 V
certainley a diode.  like you suggested.  thx.

in the centre of the board you have the transistor,  would you know which type this would be , or which type is used in the drawing of the 0227100001b that you made.

Under 0.7V across the diode would suggest it's a Schottky.

The transistor is a NPN power transistor. I've used BDW42G and BU323ZG, so look for something around similar or better ratings. You will need a heatsink!

The original part may be described somewhere in this thread...
1993 "Pearl Blue" W124 280TE
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UTn_boy

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Re: Reverse engineering the Bosch K-Jet ignition module
« Reply #82 on: 06 November 2021, 08:14 AM »
The transistor will have it's nomenclature on the top of it.  You will have to disassemble and un-solder the circuit board to gain enough access to see which type it is.  As Lucas stated, there are several equivalents to the original or better, but there are also plenty of the originals floating around.  They're like a light bulb or a fuse in that they don't go bad with age if they're never been used, so don't worry about using a new old stock 40+ year old transistor.  I've done it numerous times. 
1966 250se coupe`, black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3, papyrus white/dark red leather
1971 280sel Black/black leather
1973 300sel 4.5, silver blue metallic/blue leather
1976 280s astral silver/blue MB Tex

ptashek

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Re: Reverse engineering the Bosch K-Jet ignition module
« Reply #83 on: 06 November 2021, 09:00 AM »
That transistor is nothing special, really. And yes, they're unlikely to  be the source of issue.

The markings on these transistors are cryptic at best. Nothing that helps identifying without analysing the circuit itself.
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UTn_boy

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Re: Reverse engineering the Bosch K-Jet ignition module
« Reply #84 on: 07 November 2021, 12:01 PM »
Cryptic as in the numbers can't be read or cryptic as in nothing of the makers' marks makes sense?   I've never had any trouble reading the numbers off, typing them into ebay and finding the exact match.  They used Siemens, Phillips, and RCA.  Each maker has it's own type of nomenclature, but is recognized by many search engines. 

By the time the W116 had come along Bosch had switch to Silicone transistors, as the earlier ones used in W108, W109, W113, W114, W115, W100 were Germanium transistors, and had a large failure rate.  After mid 1971 is when the switch from Germanium to Silicone was made.  So the last of the W108, W109, W113, and the remainder of production of the W114. W115, and W100 had Silicone transistors on the switchgear.  What Lucas says has a lot of bearing, in that the transistors are rarely the problem in any Mercedes made after mid 1971.   
1966 250se coupe`, black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3, papyrus white/dark red leather
1971 280sel Black/black leather
1973 300sel 4.5, silver blue metallic/blue leather
1976 280s astral silver/blue MB Tex

ptashek

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Re: Reverse engineering the Bosch K-Jet ignition module
« Reply #85 on: 07 November 2021, 06:00 PM »
Cryptic as in the numbers can't be read or cryptic as in nothing of the makers' marks makes sense?

The latter. The ones I've seen just had internal Bosch part numbers on them, if any at all.

"1120008 7/32" means nothing outside of Bosch, and those parts catalogues are long gone from any resources they make available.
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE (history, resto)

PosedgeClk

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Re: Reverse engineering the Bosch K-Jet ignition module
« Reply #86 on: 08 November 2021, 12:04 PM »
That's a very early W116 unit.  Those black items would have to be a capacitor or some type of diode.....Zener, Schottky, etc.
They look like old tantalums. I have never seen black ones though. I can almost guarantee you that they are not diodes.

Tantalums can and will go bad. They grow dendrites and short between the plates usually. This happens when you go over the rated voltage or reverse them. They need to be replaced after a few decades like electrolytics.

Those old oscilloscopes on your living room floor are packed with 'em.
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UTn_boy

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Re: Reverse engineering the Bosch K-Jet ignition module
« Reply #87 on: 08 November 2021, 06:40 PM »
Cryptic as in the numbers can't be read or cryptic as in nothing of the makers' marks makes sense?

The latter. The ones I've seen just had internal Bosch part numbers on them, if any at all.

"1120008 7/32" means nothing outside of Bosch, and those parts catalogues are long gone from any resources they make available.

I'm confused......Bosch didn't make or use their own silicone transistors in this application.  They outsourced them from the aforementioned makers.  Is it possible that European market models had switchgears with different insides?  I dunno...I'm guessing here. 
1966 250se coupe`, black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3, papyrus white/dark red leather
1971 280sel Black/black leather
1973 300sel 4.5, silver blue metallic/blue leather
1976 280s astral silver/blue MB Tex

PosedgeClk

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Re: Reverse engineering the Bosch K-Jet ignition module
« Reply #88 on: 08 November 2021, 06:56 PM »
A photo of a radial black tantalum capacitor is attached.
1979 450SEL 6.9

ptashek

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Re: Reverse engineering the Bosch K-Jet ignition module
« Reply #89 on: 09 November 2021, 10:47 AM »
Cryptic as in the numbers can't be read or cryptic as in nothing of the makers' marks makes sense?

The latter. The ones I've seen just had internal Bosch part numbers on them, if any at all.

"1120008 7/32" means nothing outside of Bosch, and those parts catalogues are long gone from any resources they make available.

I'm confused......Bosch didn't make or use their own silicone transistors in this application.  They outsourced them from the aforementioned makers.  Is it possible that European market models had switchgears with different insides?  I dunno...I'm guessing here.

It may not have been made by Bosch, but it carries their part number and logo.

I've a video in my archive showing how these boards were made: https://www.youtube.com/watch?v=Nejl46f-lfY

The video clearly suggests these transistors were made in-house though.
« Last Edit: 09 November 2021, 10:53 AM by ptashek »
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE (history, resto)