Jump to content

Is there someone in the club with experience with automobile circuit boards?


Car guy in Virginia
 Share

Recommended Posts

I am afraid you might not get very good information. Sometimes electronics manufacturers go out of their way to obfuscate what parts they are using and/or what the source was. Unfortunately, that is highly likely to be the case on some politically or legally contentious thing like an airbag. Not only would they not want you to know what the components were, they would not want you working on it.

 

If you can post good pictures of the components you need to identify, we can try. I have a bit of electronics experience, as do others in here. With good pictures, you might also find the EEVblog forums useful. https://www.eevblog.com/forum/

 

Edited by Bloo (see edit history)
  • Like 1
Link to comment
Share on other sites

Whew. At some point you are gonna need sharper pics than that, but to begin...

 

A: A polarized capacitor, probably a tantalum due to it's color. The markings will tell the rest of the story, and will be needed, in detail. Also, note the band at the end and the plus next to it. This is wrong by today's standards, and the new part MUST go in the right way. Otherwise it might explode or catch fire or something. Tantalums long ago (sometimes even recently) may be labeled in a way that we would consider backwards. Do not leave this detail to chance if replacing the part. Both the datasheet for the new part and the old one must be consulted to make sure it goes on the right way.

 

B: Those appear(?) to be chokes and might be nigh impossible to identify. A good one might be measurable if it was off of the board. Unlikely to be bad.

 

C, D : Resistors or capacitors. Probably resistors. Need better pic. To replace you would need the ohms (if resistor) or capaciatance in picofarads (if capacitor). Also since these are "surface mount" aka "SMD" components, you need the size class. That is just a physical measurement you can measure with a caliper.

 

E: A capacitor, possibly a poly capacitor, but I can't really discern it's shape from that pic. Maybe ceramic. Now it is time to have a conversation about modern part markings. As my experience tends to be mostly with far older equipment, I'm a little slow with this part. "224" in this case is probably two significant digits and a multiplier. Think of the multiplier as the number of zeroes. In this case 220,000 pF (picofarads). A cap with that much capacitance is probably sold in the catalog in uF(microfarads) rather than pF. Move the decimal 6 spaces left for uF. This is a 0.22uF capacitor. YKA could be a lot of things. Maybe a date code, maybe more useful information. You will need to know the working voltage rating of any capacitor you might intend to replace. That isn't always easy, and may require research, but it is necessary. You can go higher with a new part but never lower on the working voltage. The tall V might be Vishay, a capacitor manufacturer.

 

F: Probably carbon film resistors. Maybe chokes. Maybe even capacitors but probably not. A view from the side and an accurate interpretation of the color bands is necessary. If the colors don't make sense in either direction as a resistors, probably chokes. You must pay attention to wattage in resistors. You can go higher but not lower. When replacing with similar old fashioned parts, physical size is a huge clue and often good enough.

 

G: Semiconductorrs of some sort. Probably bipolar transistors or maybe FETs. Could even be a two-diode pack or something. Markings are everything here.

 

H: If thats black , I'd say its a resistor. Two significant digits and then a multiplier, like the capacitor. 333 means  33,000 Ohms. Probably catalogued in Kiloohms. Move the decimal 3 places left. 33Kohm, or 33k in a catalog.

 

If you see an "R" in the middle on one, like 3R3, it is a decimal point, and there's no multiplier. 3R3=3.3ohms. I think this convention of using R for a decimal is also used on capacitors.

 

I: A bunch of interference suppression parts on a connector (my guess). Probably capacitors(?). How sure are you there are no marks? If you don't have a loupe, you better get one. There could be other components mixed in that mess. The values might not be highly critical, but cant be just random. Worst case you have to test them. Ones to test for value would probably have to come off a spare scrap board.

 

J: A mounting pad for a chip that is not present. Probably an option that was not used in this version. If there is no damage or evidence that someone REMOVED a chip, it is best ignored.

 

K: I have no idea. Maybe the traces are jumpers that can be cut to calibrate or configure something? best left alone I think.

 

L: That's not how 5 volts is achieved on any board full of chips. There is a regulator. Thats probably it to the right. Get the first line of numbers (maybe LM-somethingorother) and google it. Maybe it's a 5 volt regulator. The other things don't seem to have enough bands to be resistors. They're probably chokes for interference suppression.

 

https://www.wikihow.com/Read-a-Capacitor

 

https://www.digikey.com/en/resources/conversion-calculators/conversion-calculator-smd-resistor-code

 

https://www.electronics-notes.com/articles/electronic_components/capacitors/capacitor-codes-markings.php

 

https://www.te.com/usa-en/products/passive-components/resistors/intersection/resistor-color-codes.html

 

 

Edited by Bloo (see edit history)
Link to comment
Share on other sites

Wow, fantastic!

 

A. has an orange top stripe, yellow body, the letters "S+M", the #s 336 and 16V, and then small letters LH and small # 79.  So 33,000,000 pFs?  Or 33milliFs (see my pF/uF/mFcomment on E below)?  And why 16V?  What is the significance of 16V here?  [I think the destination chip on the circuit board to/from A "may" be the circuit board's serial I/O chip communicating the board's related air bag statuses.) 

 

Okay, so here's the A routing.  This tantalum cap traces from its + marked orange top stripe end outward to both one of the 2 smaller-height vertical capacitors on the circuit board [each being 35V 220 uF - which I'm presuming are 1 per seat belt pretensioner ignitor circuit ... (there also are 2 taller-height 35V 470 uF caps presumably 1 per front air bag ignitor circuit)] and to "under the middle" of the "little barrel" B (when you say B is a choke, this means inductor or coil, right?) and then to F (whose "resistor" colors white, black, white, gold would be an enormous 90 * 10 to the 9th ... 90B ohms, so not a resistor then, right?, so then F is a coil/inductor/choke, right?) and then from F to the given chip's pin.  So, A (capacitor) to B (what???) to F (coil/inductor/choke) to chip pin.  And, then the very next pin on that chip has its trace going back to the other end of F and then to the negative end of B.  Now B (the little barrel) has orange on one end (+) and green on the other end (-) with a tiny gap in between where it looks like you can see into the barrel (aluminum-like). 

So, when A traces to under the middle of B, is the trace conducting to a contact point in B's middle in between the orange and green - and if so what is happening there ... given now what you think B may be?  Why the A to B-middle contact? 

And, in revisiting A & B and the sequence, what do you think the functional A-B-F-chip sequence is doing?  What is the electrical effect?  Taking max 16V-capacitance (A) and choking it (B) and then choking it again (F) before entering the chip?  The trace from A to B to F to the chip is thick (not thin like most of the board's other smaller circuits).  The trace back from the chip-F-B (negative) is slightly less thick, but still thicker than the board's other thinner traces.

 

B - really curious as to what it is ... especially if its upstream trace F is a choke/inductor/coil.  Two chokes/coils/inductors in a row - B and F?

 

Education please.

 

C, D, & I - I was thinking these were noise suppression capacitors.  And, yes, I has one for each circuit - pin - coming and going into and out from the main connector.  I know the main MCU is supposed to have a noise suppression device right next to its 5V supply, and indeed it does ... one of these, just like C.

And, each one has white ends and a tan (or gray) middle, and no # (that can be seen).  All the Cs on the board are the same small size, and there's 1 D (larger size) and 1 other one slightly larger still, and 1 smaller one than the various Cs.

 

E any chance this is a capacitor that results in a specific clock or frequency (oscillator) for the chip it connects to?  E - on one of its pins - has a thick trace going into the chip - whose datasheet I can't find but believe to be 4 MOSFETs (do you have access to datasheets?) - and has a thinner trace coming back (on the next chip pin over) to its (E's) other pin.  

E wouldn't the Vishay (huge thanks for that logo company name!) "220,000 pF (picofarads)" be 220 uF (rather than .220 uF)?  pF=.000,000,001 and uF=.000,001 and mF=.001, right?

 

F how do I interpret the colors of the coil/inductor/choke (since it appears to too high to be a resistor)?   Or do you think they may be capacitors after all?  No #s, just the color stripes.

 

G these letters are extremely hard to see (on that single teenist chip), even with a magnifier.  But, they appear to be "1Fp" (yes, 1Fp, not 1pF) followed by two sideways/perpendicular letters where the first letter I can't make out and the second letter may be a G.  Maybe QG (or maybe QC).  Any additional insight into this teeny chip now?

 

H in sync (resistors).

 

J I love your thoughts on space not needed for the given board!  the 2 rows of equally spaced 7 pins perfectly fits a 14-pin chip now that I focus in on that central part of the J grid.  But I was puzzled to say the least when, for example, I traced a pin from the air bag controller chip to one of the super narrow tiny "slit" solders in the J grid - where that slit solder doesn't connect to anything ... but ... I hadn't mapped out ALL those grid lines ... 

 

K fascinating that you mentioned cut to calibrate something.  The on-circuit-board accelerometer comes with a calibration code bar-code-stamped on it to make it easy to "automatically calibrate the sensor during assembly." 

 

L very interesting you spotted the device to the right.  It's a Reverse battery and overvoltage protection chip, whose datasheet I have, and have gone through, specifically looking for the 5V step-down.  But, the datasheet didn't mention anything about any V step-down.  Never found anything indicating 5V.  (It's rated 40A and 40V.) 
So, back to the 3 Ls ... and the 5V for the board's chips/circuitry.  Tracing shows ignition V input pin (from the main connector) going to the RBO and then to an F choke/inductor/coil (or cap, pending your answer to F above) and then to these L chokes?/inductors?/coils ... and then to the chips.

So, what am I missing in regard which device(s) are stepping down and regulating the V to the 5 needed by the MCU (and others)?  Is the RBO still doing it, even though it doesn't so indicate in its documentation??

 

Also, do you recognize the logo in the attached picture?  What company was this?

 

Thanks!

 

 

1998036040_Circuitbddevicestoid-pic4of4.jpg.c3067540b89b3f06aeabd272a4813a9a.jpg

 

 

Edited by Car guy in Virginia (see edit history)
  • Like 1
Link to comment
Share on other sites

Hmmm. don't recognize the logo.  Just to add a little. F are resistors  H isn't clear but if they have 3 connections they are transistors. 

The "grid maze" as you call it may just be connections to traces on the other side. Or it could even be a multi layered board 

  • Like 2
Link to comment
Share on other sites

A: 33uf Tantalum (microfarad, not millifarad, millifarad would be huge), 16v working voltage. 16v is the most it can take, and since its a tanatlum it probably cant take that. They used to run them at 80 percent of rating like you might with some other kind of capacitor. they didn't hold up. If you replace, always go higher on the working voltage. Dont believe any polarity marks, especially on the board. Also especially don't believe the stripe. If you can find a (+) on the cap itself you can believe it. Otherwise read the datasheet.

 

A stripe like that would mean negative on any other type of polarized cap newer than 1975 or so, and most of them long before that. Not tantalums though.

 

16 hours ago, Car guy in Virginia said:

Okay, so here's the A routing.  This tantalum cap traces from its + marked orange top stripe end outward to both one of the 2 smaller-height vertical capacitors on the circuit board [each being 35V 220 uF - which I'm presuming are 1 per seat belt pretensioner ignitor circuit ... (there also are 2 taller-height 35V 470 uF caps presumably 1 per front air bag ignitor circuit)] and to "under the middle" of the "little barrel" B

That's believable, but I really have no idea. I'm from the vacuum tube era LOL. I do seem to recall that the first generation Ford airbag systems fired the airbag with a couple of big electrolytic capacitors.

16 hours ago, Car guy in Virginia said:

(when you say B is a choke, this means inductor or coil, right?)

Yes. Blurry, but looks literally wound with tiny magnet wire, if so then its an inductor or coil.

16 hours ago, Car guy in Virginia said:

and then to F (whose "resistor" colors white, black, white, gold would be an enormous 90 * 10 to the 9th ... 90B ohms, so not a resistor then, right?, so then F is a coil/inductor/choke, right?)

Whenever the color bands make no sense, it's probably a choke or capacitor. If you lift a lead and measure it with an ohmmeter, a capacitor will be open circuit, and a choke will be nearly a dead short. It could also be an extremely low ohms resistor with 3 significant digits and gold as the multiplier 90.9 ohms. That would be a precision rating though, so I doubt it's the answer. If it were there should be a tolerance mark.

 

16 hours ago, Car guy in Virginia said:

and then from F to the given chip's pin.  So, A (capacitor) to B (what???) to F (coil/inductor/choke) to chip pin.  And, then the very next pin on that chip has its trace going back to the other end of F and then to the negative end of B.  Now B (the little barrel) has orange on one end (+) and green on the other end (-) with a tiny gap in between where it looks like you can see into the barrel (aluminum-like). 

So, when A traces to under the middle of B, is the trace conducting to a contact point in B's middle in between the orange and green - and if so what is happening there ... given now what you think B may be?  Why the A to B-middle contact? 

And, in revisiting A & B and the sequence, what do you think the functional A-B-F-chip sequence is doing?  What is the electrical effect? 

I don't know.

 

Also if that is orange and not magnet wire, it isn't necessarily a choke.

 

16 hours ago, Car guy in Virginia said:

The trace from A to B to F to the chip is thick (not thin like most of the board's other smaller circuits).  The trace back from the chip-F-B (negative) is slightly less thick, but still thicker than the board's other thinner traces.

Probably bypassing(?). Keeping a stable power source for the chip, and keeping any noise the chip makes from feeding back into other stuff connected to the same power supply. That is a wild ass guess.

16 hours ago, Car guy in Virginia said:

B - really curious as to what it is ... especially if its upstream trace F is a choke/inductor/coil.  Two chokes/coils/inductors in a row - B and F?

Beats me. I thought b was a choke initially because I thought the "orange" was magnet wire. Too blurry. It's probably not a choke.

16 hours ago, Car guy in Virginia said:

C, D, & I - I was thinking these were noise suppression capacitors.  And, yes, I has one for each circuit - pin - coming and going into and out from the main connector.  I know the main MCU is supposed to have a noise suppression device right next to its 5V supply, and indeed it does ... one of these, just like C.

I are noise suppression for sure. Probably capacitors. There could be some diodes in that mess or resistors too. Any that do exactly the same thing, like go from pins to ground, are probably all the same component. The others are a crapshoot.

16 hours ago, Car guy in Virginia said:

And, each one has white ends and a tan (or gray) middle, and no # (that can be seen).  All the Cs on the board are the same small size, and there's 1 D (larger size) and 1 other one slightly larger still, and 1 smaller one than the various Cs.

I don't know. Some of that looked brownish in the pics. Brown/tan ones are most likely capacitors.

 

16 hours ago, Car guy in Virginia said:

E any chance this is a capacitor that results in a specific clock or frequency (oscillator) for the chip it connects to?  E - on one of its pins - has a thick trace going into the chip - whose datasheet I can't find but believe to be 4 MOSFETs (do you have access to datasheets?) - and has a thinner trace coming back (on the next chip pin over) to its (E's) other pin.  

Not really. It could be part of some circuit like that, but the frequency determining part would be a crystal or a ceramic resonator of some sort I would think. It is unlikely to be stable enough otherwise.

16 hours ago, Car guy in Virginia said:

E wouldn't the Vishay (huge thanks for that logo company name!) "220,000 pF (picofarads)" be 220 uF (rather than .220 uF)?  pF=.000,000,001 and uF=.000,001 and mF=.001, right?

No. The three you will run into today are pF, nF, and uF.

 

Picofarads (pF), were also known in the past as uuf, mmf, micromicrofarads or "mickey mikes".

 

Nanofarads (nF) are arrived at by moving the decimal 3 places left. Almost never used in the US until fairly recent times. The Europeans used it for ages though.

 

Microfarads (uf) are arrived at by moving the decimal point another 3 places left, or a total of 6 places from picofarads. The "u" is the Greek letter mu when it is available, otherwise use a u. Also known as mf, mfd, MF, MFD in the past.

 

Of interest in that list is mf or MF, which is REALLY millifarads or megafarads or something, so technically wrong. Only microfarads and picofarads were used in electronic service back then so nobody cared. You wont run into that unless you start working on older things than what is in your post.

 

220,000pf >> move 6 places left >> 0.22uf

 

16 hours ago, Car guy in Virginia said:

F how do I interpret the colors of the coil/inductor/choke (since it appears to too high to be a resistor)?   Or do you think they may be capacitors after all?  No #s, just the color stripes.

Little if any standardization on that years ago. There may be now, but if so I don't know about it. I imagine what you have will be some mutation of the resistor color code in either microhenries or millihenries. Most likely picofarads if they are capacitors, and probably low values.

16 hours ago, Car guy in Virginia said:

 

G these letters are extremely hard to see (on that single teenist chip), even with a magnifier.  But, they appear to be "1Fp" (yes, 1Fp, not 1pF) followed by two sideways/perpendicular letters where the first letter I can't make out and the second letter may be a G.  Maybe QG (or maybe QC).  Any additional insight into this teeny chip now?

It's not ringing any bells.

 

16 hours ago, Car guy in Virginia said:

K fascinating that you mentioned cut to calibrate something.  The on-circuit-board accelerometer comes with a calibration code bar-code-stamped on it to make it easy to "automatically calibrate the sensor during assembly." 

I sort of doubt that is really it, but such things have been done in electronic gear in the past. Not much, but it's not unknown.

 

16 hours ago, Car guy in Virginia said:

L very interesting you spotted the device to the right.  It's a Reverse battery and overvoltage protection chip, whose datasheet I have, and have gone through, specifically looking for the 5V step-down.  But, the datasheet didn't mention anything about any V step-down.  Never found anything indicating 5V.  (It's rated 40A and 40V.) 
So, back to the 3 Ls ... and the 5V for the board's chips/circuitry.  Tracing shows ignition V input pin (from the main connector) going to the RBO and then to an F choke/inductor/coil (or cap, pending your answer to F above) and then to these L chokes?/inductors?/coils ... and then to the chips.

So, what am I missing in regard which device(s) are stepping down and regulating the V to the 5 needed by the MCU (and others)?  Is the RBO still doing it, even though it doesn't so indicate in its documentation??

ANYTHING using a 5 volt supply on chips needs a voltage regulator, it is just never done any other way, and that goes x1000 in a car. A 12v car is 12.6 volts fully charged and off, less if discharged, 14.7-ish running and may have electrical noise (spikes) in some cases 100-200 volts. A computer-era car is cleaner but the point stands. If you use resistors, the dropped voltage will be proportional to the system voltage. You can't have that when logic chips are trying to figure out the difference between 0v and 5v every clock cycle, never mind that they are sensitive to overvoltage and might burn out.

 

If there is no 5 volt regulator chip. Read about zener diode shunt regulators. In the simplest form, there is a series resistor, and then a 5v zener diode to ground. The zener draws whatever is needed to keep the line at 5 volts. It is inefficient and usually runs hot and so does the series resistor. When the equipment draws more current, the zener draws less. Another way is to use a power transistor, and just use the zener to control is. Thats basically the same thing as the regulator chip, but built from discrete parts.

 

16 hours ago, Car guy in Virginia said:

 

Also, do you recognize the logo in the attached picture?  What company was this?

I don't recognize it.

 

Edited by Bloo (see edit history)
  • Thanks 1
Link to comment
Share on other sites

Please br careful with this. Worked many years in collision repair. Early airbags are dangerous. They were designed to deploy only if you were going to die. They are not a soft pillow. Nothing should be a guess. 

Even my pull a part places will not sell used parts due to liability issues.

  • Like 5
Link to comment
Share on other sites

12 hours ago, Car guy in Virginia said:

Wow, fantastic!

 

A. has an orange top stripe, yellow body, the letters "S+M", the #s 336 and 16V, and then small letters LH and small # 79.  So 33,000,000 pFs?  Or 33milliFs (see my pF/uF/mFcomment on E below)?  And why 16V?  What is the significance of 16V here?  [I think the destination chip on the circuit board to/from A "may" be the circuit board's serial I/O chip communicating the board's related air bag statuses.) 

 

Okay, so here's the A routing.  This tantalum cap traces from its + marked orange top stripe end outward to both one of the 2 smaller-height vertical capacitors on the circuit board [each being 35V 220 uF - which I'm presuming are 1 per seat belt pretensioner ignitor circuit ... (there also are 2 taller-height 35V 470 uF caps presumably 1 per front air bag ignitor circuit)] and to "under the middle" of the "little barrel" B (when you say B is a choke, this means inductor or coil, right?) and then to F (whose "resistor" colors white, black, white, gold would be an enormous 90 * 10 to the 9th ... 90B ohms, so not a resistor then, right?, so then F is a coil/inductor/choke, right?) and then from F to the given chip's pin.  So, A (capacitor) to B (what???) to F (coil/inductor/choke) to chip pin.  And, then the very next pin on that chip has its trace going back to the other end of F and then to the negative end of B.  Now B (the little barrel) has orange on one end (+) and green on the other end (-) with a tiny gap in between where it looks like you can see into the barrel (aluminum-like). 

So, when A traces to under the middle of B, is the trace conducting to a contact point in B's middle in between the orange and green - and if so what is happening there ... given now what you think B may be?  Why the A to B-middle contact? 

And, in revisiting A & B and the sequence, what do you think the functional A-B-F-chip sequence is doing?  What is the electrical effect?  Taking max 16V-capacitance (A) and choking it (B) and then choking it again (F) before entering the chip?  The trace from A to B to F to the chip is thick (not thin like most of the board's other smaller circuits).  The trace back from the chip-F-B (negative) is slightly less thick, but still thicker than the board's other thinner traces.

 

B - really curious as to what it is ... especially if its upstream trace F is a choke/inductor/coil.  Two chokes/coils/inductors in a row - B and F?

 

Education please.

 

C, D, & I - I was thinking these were noise suppression capacitors.  And, yes, I has one for each circuit - pin - coming and going into and out from the main connector.  I know the main MCU is supposed to have a noise suppression device right next to its 5V supply, and indeed it does ... one of these, just like C.

And, each one has white ends and a tan (or gray) middle, and no # (that can be seen).  All the Cs on the board are the same small size, and there's 1 D (larger size) and 1 other one slightly larger still, and 1 smaller one than the various Cs.

 

E any chance this is a capacitor that results in a specific clock or frequency (oscillator) for the chip it connects to?  E - on one of its pins - has a thick trace going into the chip - whose datasheet I can't find but believe to be 4 MOSFETs (do you have access to datasheets?) - and has a thinner trace coming back (on the next chip pin over) to its (E's) other pin.  

E wouldn't the Vishay (huge thanks for that logo company name!) "220,000 pF (picofarads)" be 220 uF (rather than .220 uF)?  pF=.000,000,001 and uF=.000,001 and mF=.001, right?

 

F how do I interpret the colors of the coil/inductor/choke (since it appears to too high to be a resistor)?   Or do you think they may be capacitors after all?  No #s, just the color stripes.

 

G these letters are extremely hard to see (on that single teenist chip), even with a magnifier.  But, they appear to be "1Fp" (yes, 1Fp, not 1pF) followed by two sideways/perpendicular letters where the first letter I can't make out and the second letter may be a G.  Maybe QG (or maybe QC).  Any additional insight into this teeny chip now?

 

H in sync (resistors).

 

J I love your thoughts on space not needed for the given board!  the 2 rows of equally spaced 7 pins perfectly fits a 14-pin chip now that I focus in on that central part of the J grid.  But I was puzzled to say the least when, for example, I traced a pin from the air bag controller chip to one of the super narrow tiny "slit" solders in the J grid - where that slit solder doesn't connect to anything ... but ... I hadn't mapped out ALL those grid lines ... 

 

K fascinating that you mentioned cut to calibrate something.  The on-circuit-board accelerometer comes with a calibration code bar-code-stamped on it to make it easy to "automatically calibrate the sensor during assembly." 

 

L very interesting you spotted the device to the right.  It's a Reverse battery and overvoltage protection chip, whose datasheet I have, and have gone through, specifically looking for the 5V step-down.  But, the datasheet didn't mention anything about any V step-down.  Never found anything indicating 5V.  (It's rated 40A and 40V.) 
So, back to the 3 Ls ... and the 5V for the board's chips/circuitry.  Tracing shows ignition V input pin (from the main connector) going to the RBO and then to an F choke/inductor/coil (or cap, pending your answer to F above) and then to these L chokes?/inductors?/coils ... and then to the chips.

So, what am I missing in regard which device(s) are stepping down and regulating the V to the 5 needed by the MCU (and others)?  Is the RBO still doing it, even though it doesn't so indicate in its documentation??

 

Also, do you recognize the logo in the attached picture?  What company was this?

 

Thanks!

 

 

1998036040_Circuitbddevicestoid-pic4of4.jpg.c3067540b89b3f06aeabd272a4813a9a.jpg

 

 

 

I wish you would let us know what vehicle you are working on.

 

As for the logo, I would guess Delco Electronics/ division of GM

  • Like 2
Link to comment
Share on other sites

+1 above. 

I have 4 years electronics training many years ago and am an Amateur Radio licensee. The fact you are asking about so many myriad of components suggests this is not a project to just delve into (sort of like reading a text on Neurosurgery and then asking to scrub in). Additionally, consider that there may be absolutely no hardware problem but a software issue especially if a light is on. Thus there is no way to diagnose a hardware issue if you are not checking the hexadecimal code and looking for thrown errors first. Also as soon as you replace a component (well same as if the board has been disconnected like now) the software needs to be interrogated. This is digital electronics so there is no "analog" way to repair or troubleshoot it like you are implying. The only "easy" thing to do is to look for stress fractures to the soldering but being real careful on all surface mounted semiconducters - and fixing that...But still the software needs a reset - so again step 1, what software program do you intend to use?

  • Like 1
Link to comment
Share on other sites

...just to addend my last comment to be 100% clear. There are numerous digital circuits which can have a trigger. Once the circuit is triggered it will never reset unless programmed to. Pulling the power, replacing electronic components, etc will not reset it. Airbag circuits are such. Also alarm systems are such. Thus again, a software program or raw comprehension of the hexadecimal code, knowing where to look, what normal vs abnormal values are, and reseting is really the first step.

   Speaking of hexadecimal, people have hacked some of the BMW code. Using this I have previously reprogrammed the power steering assist, accelerator sensitivity and other attributes on prior car of mine. Once done there is no way someone can figure it out unless going through pages and pages of hexadecimal and comparing the tables of normal and looking for any value that doesn't match (and hoping this has something to do with what one is looking for).

  • Like 1
Link to comment
Share on other sites

Bloo, huge thanks again.  In sync on everything except B, F, and L.  Incidentally, confirmed your insights on the unpopulated grids - mapped all those connections ... and lack thereof, which yielded the confirmation.  And, actually there were 4 unpopulated pads (some smaller ones).

 

Which is one of the reasons I'm so late getting back ... 

 

So, here are close-ups of B and F and L, and here is the datasheet for the RBO.

 

Thoughts now on what B is ... and F ... and L is ... and whether the RBO is or is not the 5V regulator, given the (ignition V-to-)RBO-to-L-to-chips sequence?

 

Incidentally, can't recall if I mentioned, but the chip that processes the serial I/O to/from the data port does not go through the RBO.  It only goes through one of the Ls and then one of the white/tan/white interference suppression capacitors - all of which can be seen in the last image (bottom right).  In fact, that cap is the largest of those types on the board.

 

 

22 hours ago, Bloo said:

fired the airbag with a couple of big electrolytic capacitors.

 

And on this thought, there are 4 large caps on the board - 2 35V 220 uF and 2 35V 470 uF.  Do you think each one is for a given ignitor?  2 small ones for the pretensioners and 2 larger ones for the air bags?  The pretensioners fire with 1.0A for 2mS and the air bags 1.75As for 2mS.  Or, given your comment, do you think they are used in pairs (in series) - one pair for the pretensioners and the other pair for the bags? 

 

https://www.st.com/resource/en/datasheet/rbo40.pdf

 

 

981445864_Close-upofBF.jpg.cf5feb49245da706462253009b29ce86.jpg

 

 

281013837_Close-upofLRBO.jpg.0191112152c075dc95554dc989d4f977.jpg

 

 

 

Larry, thanks for the DE.  That surprises me though, being this is an early Hyundai module, which I thought Siemens had built.  Siemens' # is on the module cover as the part #.  Can you reconcile this/educate me?  And, yes, the car is being AACA restored.

 

37, thanks for the diodes insight.

 

Others, no worries.  None of those things are being done.  

 

Link to comment
Share on other sites

B: With a better view, they aren't chokes. I like @37_Roadmaster_C's idea that they are diodes. The mounting is weird though. I've never seen anything like it. It looks like a lot of current capacity, and that wouldn't be typical for little glass diodes. I think it is the best guess so far.

 

How about this for an idea out of left field, maybe spark gaps? Or maybe some little gas tubes for spike suppression? I have no idea why they would be there if so.

 

F: I still cant seem to see that very well but it looks like brown-black-brown-(space)-gold. Is that right? If so, 100 ohm resistors with 5% tolerance. The wattage would have to be determined by size.

 

L: I still think they are chokes, although it remains a wild guess.

 

RBO: I read the datasheet and it is exactly what you said. No regulator inside.

 

2 hours ago, Car guy in Virginia said:

And on this thought, there are 4 large caps on the board - 2 35V 220 uF and 2 35V 470 uF.  Do you think each one is for a given ignitor?  2 small ones for the pretensioners and 2 larger ones for the air bags?  The pretensioners fire with 1.0A for 2mS and the air bags 1.75As for 2mS.  Or, given your comment, do you think they are used in pairs (in series) - one pair for the pretensioners and the other pair for the bags? 

 

I don't know. the caps for the first generation Ford units were huge compared to these and located in a separate box. The Ford units were also used in Mazdas. Airbags were a USA thing early on, so Delco wouldn't surprise me too much in an Asian car, until you said the box was marked Siemens.

 

 

Edited by Bloo (see edit history)
Link to comment
Share on other sites

B are definitely surface mount diodes

F are high watt resitors

RBO is the voltage regulator per se (I don't have data sheet but this is the phycial package of a voltage regulator which can get hot and is made to be screwed to a heat sink - doesn't have to be obviously - I'm building something with one now so I know...)

L (I can't see if surface mounted or not. I've seen this color code a million times and can't remember right now as I don't do electronics every day I admit). They look like high watt resistors and the silver and grey bands may be very close in shade....

  • Like 1
Link to comment
Share on other sites

Sorry late getting back again.  Thanks for the continuing support/help!

 

20 hours ago, Bloo said:

best guess so far.

 

The two B best-guess diodes are interfacing with a Siemens V1-1 (VB934333) 28-pin chip.  The VB sequence appears to change from board to board, but the V1-1 doesn't. 

 

Do you have access to datasheets (or know anyone who does)?  Haven't been able to find the Siemens V1-! sheet.

Also, CMD PRN258 93352015. 

And, Philips UAA1280T.

 

Any ideas how to track down these datasheets or spec sheets?

 

 

20 hours ago, Bloo said:

looks like brown-black-brown-(space)-gold. Is that right?

 

Against the orange, the stripes are hard to know for sure.  But, they appear to be tan, but there is no tan on the color chart web site provided.  So, brown would seem to be the next closest match, yes.  Does F's 100 ohms make sense circuitry-wise considering A's tantalum 333 16V cap and B's diode, thick-tracing to the Siemens chip?

 

 

21 hours ago, Bloo said:

little glass diodes

 

This reminds me to ask about another part N, in the attached image.

  

 

31443321_Close-upofN.jpg.1ab8ea545e37395c0ea8d6fe1eced7b8.jpg

 

 

On L, given that the RBO isn't providing the 5V for the chips, how does the chokes vs. high watt resistors possibilities resolve?  And, how is the Alt's 14V getting stepped down to the 5V?  The pic above (right image) shows the sequence (with the main connector in the fore where the ign V enters, leading to the RBO, then the Ls, then the chips beyond.

 

 

21 hours ago, Bloo said:

Delco

 

The # on the underside of the circuit board (where the DE logo is) reads 39.21.02.  All of the boards have this same #. 

 

 

Link to comment
Share on other sites

The chips could easily be custom, some of them anyway, and even if basically standard parts are extremely likely to have in-house numbers. On something like a safety device, they don't want you to know. I generally find datadheets just googling. The 3 big aftermarket parts suppliers will usually have a datasheet listed. I refer to Mouser, Newark, and Digi-Key. Usually it's good. Sometimes its crap, Sometimes its the wrong one, sometimes it links to a 500 page corporate catalog you have to dig through, sometimes the manufacturer has redone their site, and the link goes to their utterly useless front page, sometimes the link is dead, and sometimes there is no datasheet listed at all.

 

That brings us to the Philips UAA-1280T, later the NXP UAA-1280T. Mouser sold it once upon a time.

 

https://eu.mouser.com/ProductDetail/NXP-Semiconductors/UAA1280T-V1?qs=wUVvLa%2FZKxV1FYxW0fxUjA%3D%3D

 

Oh look, no datasheet link, not even a dead one. Also, when NXP/Freescale discontinued it they said it was for "Domestic Appliances (Hamburg)" See page 31.

 

https://www.nxp.com/wcm_documents/products/eol/dn48a.pdf

 

It is actually an airbag controller, and mentioned by various sites who were once selling them. That is all they say. I found one site in an Asian language who had a datasheet link. It was a PDF that said "the datasheet is not available online, please contact by email"

 

https://cn.exshinetech.com/products/NXP-Semiconductors-Freescale/UAA1280T-V1512.html

 

There are other places besides the big three who have a lot of datasheets, Octopart for instance. No help there though. Unfortunately, the trail for the other 2 chips was even colder.

 

They don't want you to know.

 

On 2/28/2022 at 8:30 PM, Car guy in Virginia said:

Does F's 100 ohms make sense circuitry-wise considering A's tantalum 333 16V cap and B's diode, thick-tracing to the Siemens chip?

 

I don't have the foggiest idea what is going on there.

 

On 2/28/2022 at 8:30 PM, Car guy in Virginia said:

This reminds me to ask about another part N, in the attached image.

 

I don't recognize that either.

 

On 2/28/2022 at 8:30 PM, Car guy in Virginia said:

And, how is the Alt's 14V getting stepped down to the 5V?

 

The regulator has to be there somewhere, maybe buried in some chip, maybe made with discrete parts. I suspect it would have some of the larger traces like the RBO thingie does.

 

 

Edited by Bloo (see edit history)
  • Like 1
Link to comment
Share on other sites

On 2/26/2022 at 11:24 PM, Oldtech said:

Or it could even be a multi layered board 

Yes, I've worked on PCBs with up to 6 layers! Only with a bright light can you hope to attempt to see through all that fiberglass/phenolic to trace. Ohmmeter is your best friend.

  • Like 1
Link to comment
Share on other sites

First, thanks. 

 

Another long day, but most productive, due to all the help so far.

 

So ...

it appears there are 3 main (Ign V pin-supplied) power feed paths from the RBO.  A thin trace to the ignitor circuit monitors + a thick trace that routes to all chips for their power feed (including for the ignitor power switching controllers) + a thick trace that feeds into two separate parallel sub-paths for the two taller 35V 470 uF caps - 1 sub-path per cap.  The two 470 uF caps appear - at the moment - to be supplying the current for the two front air bag ignitors. 

 

Given the 3rd path (with its two sub-paths) and considering the capacitors' sizes and roles, electrically does this point more toward their in-path 2-stripe devices being chokes (inductors) or the high watt resistors?

 

More later too, when I can get above the water line.  submerged.

 

Thanks.

P.S.  Oh, and I figured out one of the smaller 220 uF caps as well.

 

 

 

  • Like 1
Link to comment
Share on other sites

  • Peter Gariepy changed the title to Is there someone in the club with experience with automobile circuit boards?

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...