Working on fix ECUs... AND FIXING WITH SUCCESS!!!

[Nacho-RT74]

what you read... I will show you pics later but everything points out on THIS being the guilty on the MP chromed units:



with just one difference... NO MOTOROLA EMBLEM ON IT... just the ON letters... a copy of originals? dunno.. if it is, maybe that confirm the use of bad quality components ?

By the moments only was able to find the MJ10005 replacement. Is the closer I could find to the original specs but will work to discard the fail and making it work

IF IS THIS THE PROBLEM is an easy serviceable piece to replace AND CHEAP. Just need to cut the epoxy area on that location, replace and refill with any regular black silicone.

the bad is: FBO box got erased the numbers on transistors and I don't think he will be agreed on tell me that number

[Nacho-RT74]

SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!

fixed the first one... pics soon!

[Nacho-RT74]

SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!SUCCESS!!!


fixed the SECOND ONE!!!...
what I need now ? the right Transistor to get same specs from Module.

Shame FBO transistor got erased the numbers from manufacturer

[Musicman]

Nacho

I have an FBO A688 back at the house... I'll look at it tomorrow and see if I can find anything.

Mike

[Ghoste]

Good work Nacho! 

[Nacho-RT74]

Nacho

I have an FBO A688 back at the house... I'll look at it tomorrow and see if I can find anything.

Mike

Don uses sandpaper to remove numbers from Transistor to keep the secret. I don't think you'll find any number on it

[Nacho-RT74]

promised pics. Need to note these pics were taken AFTER the process of dissasembling and in fact after the first module test when the new transistor was solded and mounted on car, not allong the process, but you'll get the idea

first the steps dissasembling everything. Removing the black stuff:



how it basically looks after that:


This is the pins area... These pins are full of tin and after remove that we found they are riveted, so we had to use a Dremmel to loose them. For the test they were placed back, and full filled with tin and solded back to the printed circuit board, but to placed back stronger, is better try to drill a small hole and use a small screw to attaching THEM back, then solder back on to the printed circuit board.


these are the transistor solding points and screws... the remove process is basically just remove the tin and screw them out... fairlly easy and THE MAIN GOAL ON THIS like you will see later.


how it looks the transistor and disipator plate out of the case... fairlly easy to remove, simply pulling it out:

Need to note TEH TRANSISTOR TESTED DAMAGED once removed. But, if the transistor tested bad why we didn't stop to dissasemble and simply replaced it ? because we tried to find an internal reason for the failure.

THE GROUND POINT between case and circuit board... is basically a pin bent over the circuit board, like a nail and solded. Remove the tin and straightened up the pin


THE CIRCUIT BOARD!!!, of course when pulled out it was full sticky of the silicone, epoxy or whatever is full filled. This is already clean. Not hard to do


we checked all diodes and transistors on board, they simply gave us PERFECT measurements. Same with resistors, although for a better test they were removed at one ledge from board to don't read the ohms of the circuit, and just the resistor. ONCE AGAIN EVERYTHING WAS PERFECT.

The conclusion... Transistor simply got a premature fail by itself... maybe bad component quality ? NOW WE HAVE THE DOUBTS... which one is original and which not ? My friend told me that latelly Motorola is not using anymore the M emblem on them and now they are using the ON letters. beside this, you can note the Pn printing quality. If you search on the ebay, is funny to see all transistor stating MEXICO but... sent from China/HK ? LOL...

This is the full pieces set. You'll notice the cork. Is not more than a gasket beween circuit board and ECU plug location on Case. Of course it was glued to the silicone all the outer edge around, not the faces... this is a clean view.


You can see there the white stuff looks to be an spacer and gasket for the transistor ledges. Also the ground case location.


WE ASSEMBLIED BACK and used the closer to original specs Transistor available locally, The MJ10005. my friend who is really a tech told me the one I got is a Chinesse unit with the motorola emblem on it, not original either. But since this was a basic test, not the definitive refurbished job it was to work... LIKE IT DID!!!

[Nacho-RT74]

If you care about transistor specs, here is the original one

http://www.datasheetcatalog.org/datasheet/motorola/MJ10012.pdf

and here is the one we are using ( well maybe not an original, but should be close at least )

http://www.datasheetcatalog.org/datasheet/motorola/MJ10005.pdf

Dunno if the small diffs on specs really will affect on performance. My friend told me that even could work better, but he is not so expert to predict it. The original one is specifically made for ignition stuff as the datasheet says

[Nacho-RT74]

Now, that was the first job. Known the only component reading wrong was the transistor, we tried going straight up to that on the second box:

JUST CUTTING OUT the silicone on transistor area:


Removing screws and tin, voila, transistor out:


front face with transistor out and heat plate disipator ( or part of it )


welding back the replacement unit:


finished job on back:


( need to note will refill with black silicone but not now, will test it better on streets, after that maybe will aply a light layer of vaseline and then the black silicone to get it easy for a new service just in case, or when I get the correct transistor, Original Motorola  )

and now... THE FRONT FACE FIXED:



needles to say, that as I told you previouslly THIS UNIT WAS MOUNTED ON CAR AND ENGINE STARTED UP PERFECT ( this was the unit which died after 24 hours! )... just like the first one we reassemblied back... need to test it on streets yet

[willard]

Congrats! Finally someone pinpointed the problem and found a solution! Great news for the mopar family.

[Nacho-RT74]

specially cheap... less than $3 each, and able to do it at home if you have the skills.

so, no more $70 to spend on Chromed, or maybe $50 on Oranges. AS FAR the fail is the same, what it looks it allways be ( by now 2 of 2 )

rest to check if failure is the same on another chromed box I have around but OLD ones ( with the odd printed PN ) what printed circuit board is diff although components looks to be the same. Will replace the FBO one too, although I don't think will find the correct transistor substitute... a friend of mine have around 3 Orange ones ( one from the old days, rest newer ) and will proceed with the same.

[Ghoste]

Knowing very little about electronics, what would be the reason for Don keeping his transistor number a secret?  What aspects of the operation of the ecu would it change?

[Chryco Psycho]

What Don told me was that his transistor switches faster which in theory is what causes the timing light to wander by 2-3 degrees by switching too slow ... if you can believe what Don tells you ?

[Nacho-RT74]

If that's true THERE IS A GOOD CHANCE, the MJ1005 ( the unit I used ), could be closer to FBO specs... if you read the MJ1005 datasheet specs.

For those who still don't know, the reason why the A688 FBO unit is gone is because Standard who was the Modules manufacturer to DON, said BYE BYE to USA lands and they are building their stuff outside USA... so they weren't able to buy for him his units anymore. That's at least what he told me

[Nacho-RT74]

Being more specific on reference what you said:

What Don told me was that his trasistor switches faster which in theory is what causes the timing light to wander by 2-3 degrees by switching too slow ... if you can believe what Don tells you ?

what MJ10005 datasheet says about:

The MJ10005 Darlington transistor is designed for high–voltage, high–speed,
power switching in inductive circuits where fall time is critical.

[Musicman]

Nacho

I pulled the FBO unit apart... it's a lot different than the MP box in many ways, and not just the components. It's a little more difficult to replace parts on these units since the entire board is set in a bed of black silicon rubber. The power transistor would be easy enough, but the rest of the components would require that the board be removed, and this would be a little more time consuming... easily done, but time consuming. They're actually quite nicely made... I was actually impressed, not what I expected to find at all. I pulled the power transistor hoping there may be some info on the reverse, but no luck of course. As you said, someone purposely had the markings removed during assembly. I sincerely doubt that Don is responcible for this however, more likely it was the manufacturer.

Here's a shot of the board...



... and the power transitor with no markings of course...

[Nacho-RT74]

the circuit board needs to be removed on all the units anyway to replace any component but the amplifier

That one looks really pretty much similar to the OLD MP chromed unit I have laying around... with resistor ballast and all. AND EVEN THE COMPONENTS FACING UP. Will need to be further checked but looks to be pretty much similar, not the same but similar. Diff disposition by sure. The newer MP unit circuit board faces down the components and makes mandatory to remove for just testing.

on the printed circuit board facing up, you still can test dieletrical components ( transistors and diodes ) since their test is not affected by the circuit... not like resistors.

anyway, a blown resistor is VISIBLE. Is hard to get damaged a resistor being not the fail visible.

Just by a guess, replace the transistor with the one I used and just test it for working order, not performance... If works, then we got the failure, just need to find out the right component, which, obviouslly and logically I don't think will be informed by Don

[Musicman]

That's not a blown resistor Nacho, it just looks that way in the picture... it's just some of the old rubber. I didn't clean the board, I just took a picture of it as is. 

Looking at your pic's of the MP board and mine from the FBO unit... there are a number of differences, but I'm still betting that the MJ10005 would work in this circuit.

[Nacho-RT74]

here is the view of the Older MP Chromed box unit... note the similarities with FBO and the distance from the newer MP unit

This is with the replacement component already solded, ready to be tested.





The original unit have some numbers erased and the brand looks to be BRITAIN

it reads

87 ( something here what dunno if is some emblem or numbers ) 49
3597525
BRITAIN

[Nacho-RT74]

That's not a blown resistor Nacho, it just looks that way in the picture... it's just some of the old rubber. I didn't clean the board, I just took a picture of it as is. 

no, sorry, I'm saying a blown resistor WILL BE NOTICEABLE, just dieletric components can get failed and still looking good outside ( ex, the amplifier transistor )

so I think testing the transistors and diodes on the way is visible on box, will tell you for a good or bad component. And resistor just looking at them. That makes no need for remove the board from case and work on it like it is... diff than the newer MP units where remove the board makes mandatory for components testing.

[Musicman]

OK... that new pic makes better sence of what you were saying earlier. The old Chrome box design is "very similar" to the FBO unit.  Or more accurately stated, the FBO circuit is very similar to the old Chrome box circuit.

That said... the MJ10005 should do just fine.

[Nacho-RT74]

yes sorry, an image worths million of words

I still have not tested the Old MP box withe newer transistor...will do sometime in the afternoon

[Nacho-RT74]

New update about the older Chromed box. Didn't work quite as good. Started up fine BUT misssing some beats. Will check further on this later

Officially begining the street test time for the newer Chromed box with the replaced transistor.

[ChargerST]

Could you make a drawing of the circuit board and the components? My dad is a retired electronics teacher and he has got a cicuit board printer - need to give him something to keep him occupied  

Great work btw! 

[tan top]

awesome work Nacho    clever stuff 

[Musicman]

Could you make a drawing of the circuit board and the components? My dad is a retired electronics teacher and he has got a cicuit board printer - need to give him something to keep him occupied  

OOooooo.... I'd love to have a circuit board printer laying about..... Yea, that's just what I need, more side projects!
Cool idea though about the ECU boards, and it would be easy enough to do as it's a fairly simple circuit.... and it would give Dad something to do. Of course, if he's a retired electronics teacher I'm sure he'd be looking at ways to improve on it.

[Musicman]

Nacho

I've been looking at images of the MP boxes on the web, looking for part numbers on the power transistors, and it seems like every picture you look at shows a different part number, different place of origin, and a different manufacturer...  So much for Quality Control 

[ChargerST]

Could you make a drawing of the circuit board and the components? My dad is a retired electronics teacher and he has got a cicuit board printer - need to give him something to keep him occupied  

OOooooo.... I'd love to have a circuit board printer laying about..... Yea, that's just what I need, more side projects!
Cool idea though about the ECU boards, and it would be easy enough to do as it's a fairly simple circuit.... and it would give Dad something to do. Of course, if he's a retired electronics teacher I'm sure he'd be looking at ways to improve on it.

Haha, yeah, he likes to improve things. He designed a totally new (and different) circuit board for my tach (which was fried) - works flawlessly!

[b5blue]

Could you make a drawing of the circuit board and the components? My dad is a retired electronics teacher and he has got a cicuit board printer - need to give him something to keep him occupied  

OOooooo.... I'd love to have a circuit board printer laying about..... Yea, that's just what I need, more side projects!
Cool idea though about the ECU boards, and it would be easy enough to do as it's a fairly simple circuit.... and it would give Dad something to do. Of course, if he's a retired electronics teacher I'm sure he'd be looking at ways to improve on it.

You should have him do the gauge cluster boards! They are pricey!
  Nacho, check out Rick E. on eBay, (Ricks Mopar) he has 2 ECU's rated for 7200 RPM for sale at very reasonable pricing! Said in his listing they are made by "OEM Manufacturer"....Rick knows his stuff!

[Nacho-RT74]

Yes I know... with a decal HIREV 7500... I already have one of them... but... what can I say not convinced about them. I have been running one of them from January when my FBO unit broken up to two weeks ago, when went back to the Chromed box what just last long 24 hours... then replaced with an orange I also got to test it. ( I got on my last shipping 1 Chromed 1 Orange )

Talking about Performance by now the best two has been the FBO and the MP Chromed in that order but not by far... when worked LOL.

[Nacho-RT74]

Printed circuit board diagram... dunno if I'll be able but will try.

First two days with the fixed Chromed box ( the one I didn't dissasemblied and last longed 24 hours ) and everything perfect. Fast response without miss a beat

[ChargerST]

Printed circuit board diagram... dunno if I'll be able but will try.

doesn't have to be perfect - actually i just need to know how the lines connect and the location of the pins - then I can draw the diagram myself. Here's the diagram I made for my tach (after a drawing my dad made of course )

[Musicman]

Drawing the boards would be quite easy for me... I just need a good photo to work with... Here's a partial example using that dirty board from my previous post.

I start with the original image (the board would be all cleaned up of course).



Add the nodes and paths...



Remove the background, and there you have it!

[ChargerST]

So what's the real difference between the orange and the chrome boxes?

[Nacho-RT74]

BESIDE THE TRANSISTOR? good question! when I get some of the damaged orange box will know ( I know will get at least 3 )

Musicman, paths are on back of board ( on the FBO and old chrome box at least )

[Bob T]

Hey Nacho, good to see you have some success there. I took these pics of some I have , they might be of use because the transistor # can be seen.
They are out of Chrysler Australia from the Valiant Charger and Regals

The Blue one is the current one in my 68 R/T, however I'm not sure which one I would use for a replacement if it failed, would probably try them all. Any clues?? Not to sure what the rev range is for the blue one and which would be the equivilent out of the others . Thanks
The red one has had a repair and needs to be siliconed up again

[Musicman]

Musicman, paths are on back of board ( on the FBO and old chrome box at least )

Yes I know, but it doesn't really matter, it's still the same process, this was just used as an example.

[Nacho-RT74]

OH Ok... great LOL... didn't got it

[Nacho-RT74]

Bob T... sorry, don't know. A Real electronic tech will tell you better. I simply tried to match the existant

[Bob T]

Bob T... sorry, don't know. A Real electronic tech will tell you better. I simply tried to match the existant

Ok, no worries 

[Nacho-RT74]

If somebody else tries to fix it like this and has success, please share it!

[ChargerST]

Hey Natcho, did u get some orange boxes to do a comparison? If these boxes are pretty similar it would be cool to upgrade the orange ones to perform like the chromed boxes...

[Nacho-RT74]

will do soon, as soon my friend gets me the toasted ones he has ( 3 oranges I think )

( I already thought on that )

[Nacho-RT74]

It looks I began to miss some beats at high RPMs... maybe the Transistor is not the more adequate for this. ( or once again a quality issue )

will look further on test anyway to confirm this

[Mick70RR]

I fixed my FBO ignition module today. First of all I changed the power transistor for an MJ10005 but it still didn't work. So I dug the rest of the black stuff out and noticed that the long wirewound resistor towards the middle of the PCB was open circuit. It's a 68 ohm resistor and looks to be about 5 watts. I found four 2 watt 68 ohm resistors at work so I wired them in series/parallel to give me 68 ohms at 8 watts and soldered them in. Tried it tonight and the car fired right up. Only tried it temporarily but I might bolt it in over the weekend and see how it goes on the road.

[Nacho-RT74]

Thats nice!

Nice update!

Maybe something to check on mine too

[mhinders]

I see a potential problem comparing the 2 transistors...

The gain is different in the 2 transistors...and it may work...and it may not work. It depends on how the circuit is designed, and how the components are chosen.
The MJxxx12 transistor has a higher gain than the MJxxx5 transistor (hfe, DC current gain). If the control current is on the low side in the design with the xxx12 transistor, the xxx5 transistor may not pull the full current. It's may however easily be fixed by putting a smaller value resistor on the transistor's base connection (getting a bigger control current).

The switching characteristics cannot easily be compared since the testing setup is different.

[Nacho-RT74]

I used the 5 just because the other one wasn't available, and was for componment test what prooved ON MY CASE both modules failing on same component.

Now mick checked a diff component failure

MICK, which exactly resistor failed ? The pic posted by musicman is an FBO module

[Mick70RR]

I used the 5 just because the other one wasn't available, and was for componment test what prooved ON MY CASE both modules failing on same component.

Now mick checked a diff component failure

MICK, which exactly resistor failed ? The pic posted by musicman is an FBO module

It's the long open wirewound resistor right in the centre of the PCB. It had gone open circuit at one end. It looks like the legs are just crimped on, maybe that's the reason it failed.

[nascarxx29]

Anyone got a fix for this vintage ignition module.It to has a motorola transistor

transistorized ignition



http://www.dodgecharger.com/forum/index.php/topic,59561.0.html

[Nacho-RT74]

I used the 5 just because the other one wasn't available, and was for componment test what prooved ON MY CASE both modules failing on same component.

Now mick checked a diff component failure

MICK, which exactly resistor failed ? The pic posted by musicman is an FBO module

It's the long open wirewound resistor right in the centre of the PCB. It had gone open circuit at one end. It looks like the legs are just crimped on, maybe that's the reason it failed.

thats a ballast kind resistor as far I know

[Mick70RR]

Well I re-fitted the FBO unit this morning and took the car for a long drive. Everything seemed fine so I stopped to check the timing and noticed it was two degrees advanced from where I normally run it. I didn't check the timing with the old unit so I'm not sure if this was something to do with the FBO module or whether I had previously set it a few degrees advanced by accident. While I was out I did a few full throttle runs and did a bit of cruising round town and didn't notice anything out of the ordinary. Think I'll leave it fitted and keep the old unit in the trunk.

[nascarxx29]

Any of this ECU info current
http://www.badassmopars.com/1967coronettechElectroniccecus.htm

[ODZKing]

How about P4120505. 
The number on that Transistor are as follows:
793266
9M179 VL
9M 649
MYS
I can't seen to get that to cross to anything.   

[Mick70RR]

How about P4120505. 
The number on that Transistor are as follows:
793266
9M179 VL
9M 649
MYS
I can't seen to get that to cross to anything.   

It seems that transistor is made by ST Microelectronics and has been used on both the orange and chrome boxes. The chrome box currently for sale on the Summit website used the MJ10012 so the two transistors must be similar.

[Pete in NH]

I came across this thread from last year and the amazing work done by Nacho- RT74 on these ECU boxes. I'm a retired electrical engineer now but, back in the early 80's I did some work with the then new Motorola MC-3334 High Energy Ignition Controller. The MC-3334 was designed by Motorola for Delco's new HEI ignition system and used the MJ10012 transistor to drive the coil. There is an interesting statement in the MC-3334's application note concerning the MJ10012. It states-" A 350 volt zener clamp is required when using the standard MJ10012. This clamp is not required if using a selected 550 volt version is used". The standard MJ10012 is 400 volts.

It is quite common to have transistor manufacturers such as Motorola sort transistors for special characteristics if you are buying large quantities of them. It would not be unusual for Chrysler to have requested selected MJ10012's and have them marked with a special part number. It would save them the cost of the zener clamp diodes which would add up in the quantity of ECU's Chrysler once built. Motorola would happily do the sorting to get orders for the really large quantities involved.

Here we are 35 years later and I have to wonder if the current Orange and Chrome boxes are getting selected MJ10012's or if the people building them even know about this issue. The guy's who did the original engineering on these boxes have likely retired long ago and did the information get passed on or in the much lower quantities of these ECU's being built, perhaps by others than Chrysler, can they even get these selected transistors? All of this is an educated guess but, it wouldn't be the first time something like it caused product quality to go down hill.

This thread prompted me to do some research. I don't think Motorola is even in the transistor business anymore and may have sold out to ON Semiconductor.  I could not find any current sources for the MJ10012. I have an Orange box in my 71 Charger and it has an ST Microelectronics transistor in it.  I'm almost certain the ST transistors are a ST type BU941 which is a type specifically for electronic ignition systems. The BU941 is still available from Mouser Electronics (mouser.com) for $2.29. They have 1300 in stock but the type # is listed for end of life and will be discontinued sometime in the future. The BU941 is very close to the MJ10012 in characteristics and the data sheet also calls for clamping the voltage across the transistor to 400 volts maximum. So, the ECU's may also be using selected BU941's. One important characteristic of these ignition transistors is how fast they turn off. Both the MJ10012 and BU941 have specified turn off speeds while driving an ignition coil, types like the MJ10005 don't. Slower turn off speeds can result in weaker spark.

Back in the early 80's I had a prototype MC-3334 based Chrysler type ECU running on a test stand but not a real engine. It operated for several hundred hours before I ended the testing. It was quite a nice little box and didn't use a ballast resistor as the MC-3334 electronically limits the current through the coil.

[ODZKing]

While I am limited in my electronic knowledge, meaning I know just enough to get me in trouble most times ... this stuff amazes me.   
Good work.  I have an orange box that died on me last year if anyone wants to mess with it.

Bob

[Nacho-RT74]

as far the transistor is available, SHOULD BE... the problem is find a good and correct transistor.


also need to know that NOT ALLWAYS the transistor could be the culprit, BUT, maybe 70% of the times ? based on my experience.


Pete! if you find some "TRUSTABLE" source for the Chromed MP transistor ( Motorola, ON or any other correct replacement ), please let me know! I'll be happy to get some of them. I have being affraid to get this from a China or any other "seller", being how they can be easily false

I'm not really an engineer or electrician tech, just that being a sound tech, I'm familiar with some therms and have some skills. That's all. So any advice, or help from a real tech will be GREAT, and will save lot of Modules around, on the cheap

[Pete in NH]

I think right now the ST Micro is the best transistor for the repair I can find. ST Micro is a first class European company that produces high quality parts. I agree that I would not trust any parts from China marked MJ10012. Especially since I could not find any current production MJ10012's.

I think I would try the following as a repair when replacing the transistor. Replace the transistor with a BU941 and add the clamp diodes to protect the transistor. For the clamp diodes I would try three 1N5380B diodes in series (end to end) , with the banded ends all in the same direction. I think they might fit better if arranged in a "U" shape in the area of the big transistor. Connect the banded end to one of the transistor mounting bolts and the other end should be soldered to the side if the steel box, which is ground. This will give you a 360 Volt protection circuit for the transistor and should allow an off the shelf transistor to work in the original circuit without problems.

The BU941's are available from Mouser Electronics (mouser.com)  as part number 511-BU941 and the 1N5380B's are part number 863-1N5380BG. Mouser is an authorized ST Micro distributor and I buy parts from them frequently. I'll be buying a few spare BU941's and 1N5380B's for my self on my next Mouser order.

By the way how are you getting that black potting compound out? Usually once that stuff is poured in it's almost impossible to get it out without damaging something.

Bob, thanks for the offer. I wish I still had my little test rig for these boxes, I'd take a crack at fixing yours. Maybe it's time to build up another test rig.

[Nacho-RT74]

I never thought on replace all the black compound on the fully dissasemblied Module UNLESS find to replace the compund correctly, just really fix the one I cut at Transistors end... was to USE simply RTV silicone to fill the compound cuts up I made.


somebody gave me a website about epoxy material for electrical stuff long time ago...


I don't get what you meant about the diodes

[Nacho-RT74]

I didn't found the website I got once, but maybe something like this:

http://www.cslsilicones.com/sealants/category/electronic-and-electrical

[Pete in NH]

What question did you have about the diodes?

[ODZKing]

I'll drop it off if The Crunch play the Monarchs in the playoffs  

[Nacho-RT74]

What question did you have about the diodes?

didn't got how to fit them on circuit... but will read further your post later. I'm really distracted latelly for several personal reasons

what do you think about these MJ10012 transistors ?... do they look to be original Motorola pieces ?
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=151035623066&ssPageName=ADME:B:WNA:US:1123

[Pete in NH]

Hi Nacho,

Yes, they look like original Motorola MJ10012's. Some are also ST Micro MJ10012's. The four digit numbers under the part numbers are date codes of when the devices were made. For example 7814 = the 14th week of 1978. So, they are old enough to be real Motorola.

On the diodes, they have a white band on one end. You connect three diodes in series (end to end) with the white bands all facing in the same direction. So, you end up with one big diode. Connect the white band end to the transistor mounting screw connection which is the collector of the transistor. The other end of the diode connects to the metal case of the ECU.

[Nacho-RT74]

Connect the white band end to the transistor mounting screw connection which is the collector of the transistor. The other end of the diode connects to the metal case of the ECU.

that was my question... thanks!

[Nacho-RT74]

I won the auction and already in hands ( I'm in Spain right now )... althought I was interested just on the ones for the chromed ECU... what could be the applications for the other two ?

MJ2501 and MJ3001

searchinga round for datasheets, it seems they are somekind related

[Pete in NH]

Hi Nacho,

Yes, the MJ2501 and MJ3001 are related. They are what is called a complimentary pair and are used together in audio amplifiers. The MJ2501 is a PNP type, the MJ3001 is a NPN. Both are 80 volt 10 amp devices with very high gain. Gain= 4000 at 5 Amps. Both are not suitable for ignition systems, voltage is too low and the 2501 is the wrong polarity. I have the data book on these if you need more information.

[Nacho-RT74]

yeap, read later the PNP and NPN configuration making them complimentary. Would be nice what kind of audio amps could use it, since I work with Audio stuff.

I found the PDFs for them... will search further what kind of audio amps could use those

[Pete in NH]

An update on the replacement transistor situation for the Chrysler ECU's. I tried ordering some MJ10012's from a distributor that claimed to have them in stock several months ago. Recently they canceled my order and send a refund.  I take it they are no longer available. I have been unable to find any other source for MJ10012's other than Ebay.

On the ST Microelectronics BU941P in a metal case, called a TO-3 package, I was able to order 5 pieces from Mouser Electronics. Shortly after receiving them I was informed by Mouser they were being discontinued by ST. I checked the Mouser website and the metal case BU941P's are no longer available.  ST Microelectronics has replaced them with a newer type the BU941ZP. This new transistor now contains a protective zener diode mentioned in my previous posts. That's the good news, the bad news is they are only available in a metal and plastic package that is completely different from the old all metal type.

This makes me wonder what the future of the orange and chrome Chrysler ECU's might be. Will they get redesigned to use the new transistors? Did Chrysler buy a whole lot of metal cased transistors, known as a last time buy, to keep building ECU's for a while longer? Or, will these boxes simply disappear because there is little interest in supporting 30 some year old technology with little demand? I guess time will tell.

[Ghoste]

I'm going to go with your last guess.

[Nacho-RT74]

well, at least I have 2 originals... Hope they are really fine.

wondering now about the FBO piece. I don't think Don will share the info of those... or Yes?

[beat]

hi nacho,
by surching for the keyworth MJ10012 I cam to your interesting post.
not as I own ore repair such big cars as you, no, I do just made my own transistoriced Ignitions for my 1973 english Motorcycle.
and I do use the Mj10012 from this Ebay seller from Canada, the stuff is sent from Hongkong / China.

and I have to say, - they are good quality.

the last one was working 6 years, a very simply circuit with a zenerdiode of 8 Volt and a 27 Ohm Resistore on the BASE and a 376 V zenerdiode across the Colector / Emiter.
and the most important:  I know why it is brocken down now!

a Voltage drop in the all wiring was the reason, caused by a brocken MAINSWITCH Contact.
so this cheap MJ10012 doing a good job, just a very low Voltage is killing them for shure.

if you are interested I can send you a copy of the circuit of this first generation Trans. Switch and as well a circuit of the new generation, using a NTE98 Transistore and a 7805 Voltage Regulator on the BASE for more stable voltage to the BASE.
greetings
beat

[Nacho-RT74]

all I can say is I don't really understand everything about electronic components LOL...

[Nacho-RT74]

It seems we got a newer suplier for Chromed boxes?

http://www.ebay.com/itm/Mopar-Ignition-Control-Unit-P4120534-/271373671855?pt=Motors_Car_Truck_Parts_Accessories&hash=item3f2f219daf&vxp=mtr

Note diff decal and transistor!

[Pete in NH]

Hi Nacho,

The transistor in that ECU is almost certainly a ST type BU-941P which was discontinued by ST last November. Someone may have done a big last time buy and put a large number of transistors on their stock shelf. It will be interesting to follow these ECU's over time. Sooner or later there will be no more transistors.