Marine MTU ECU

[2PAC Mafia]

Hello,

I have a MTU old ECU to repair. It´s based on a MC68332 microprocessor. I can´t enter inside the ECU with the usual software with PC because I see it´s like in reset state (seems not in reset but it´s blocked). When I checked the reset pin at MC68332 which should be in H state I have pulses, peaks to L state. I guess something associated to D0, D8 and D9 signals not correct...

Then I have a question because I have no experience about microprocessors, I´ve seen on the board a connector with 10 pin going to processor which should be for programming or at least access on the processor. I´ve seen in Internet also there are development boards to work with these processors, if I have one of these development boards is possible to access to this processor and check behavieur or is it blocked by the manufacturer? Can I download the program from the processor, put a new one and program it again with downloaded software?
Thanks. Best regards.

 

[alec_t]

Can I download the program from the processor

Isn't the program held in non-volatile memory external to the processor?

 

[2PAC Mafia]

Hi Alec_t,

thanks for the answer. Yes there are 4 memories as EPROM plus 2 RAM. These memories contains important software and without them the unit is not working, it goes in reset mode. I can read them with my programmer and I know they are OK because I tested them swapping on another unit I have which is working. But my question is if all instructions, software and so on are stored in these external memories, so if the processor have some problem itself and I put a new virgin one, should it work without programming anything internally? Is it taking all software from external components? Regards.

 

[dr pepper]

If the chip is receiving reset pulses then maybe the fault is external to the software side, ie maybe theres a brownout circuit or something, either that or there is a micro supervisor system.

 

[alec_t]

should it work without programming anything internally?

I don't know, but on a quick scan of the manual I didn't notice any non-volatile memory locations in the memory map. The reset vector has a default value at power-up.

 

[dr pepper]

Do you have all the power rails?, older eproms need -5v and probably comes off a negative reg ic.

 

[2PAC Mafia]

Thanks everybody again,

I took some pictures of the oscillograms:

http://www.restoretronic.com/descargas/ecu/1.jpg

This is the peaks at reset pin on processor at ECU which is not working.

http://www.restoretronic.com/descargas/ecu/3.jpg

These are values of the oscillogram.

http://www.restoretronic.com/descargas/ecu/2.jpg

This is same pin at ECU which is working.

http://www.restoretronic.com/descargas/ecu/4.gif

Reset schematic.

I have no schematic but I´ve seen configuration is very similar from other which I have schematic. The lines D0, D8 and D9 I guess are the cause of the peaks at reset pin. Supervisor IC MAX707 output is at oVdc.

I think no -5Vdc power needed but I´ll check. EEPROMS are AT28C256 (x2) and AM29F010 (x2)

 

[dr pepper]

Its impossible to diagnose via proxy, however some ideas:
The max 707 is a supervisor as you say, it will reset the chip if there is a reset input, or the vcc voltage to the chip is too low, or if the comparator section of the chip is under threshold.
It would stand to reason that either the processor supply is too low (have you measured it) or the comparator threshold is below the setpoint, I dont know what the comparator is looking at, it may just be battery voltage, the management may shut the engine down if the battery is too low, esp if the throttle is servo controlled or the cooling system is electric.
Your right about the eproms, Later ones dont need -5v, however I'm thinking your issue is power supply, or some run condition isnt met.
looks like battery voltage is 24v, are we talking a larger engine, mtu make some interesting motors.
I've had experience of diesels before, but only small stuff.

 

[2PAC Mafia]

Hi Dr Pepper,

output of MAX707 is LOW so as it goes to the base of a transistor it switches when is HIGH output. At processor reset input we really have pull up signal but with these peaks to ground, this is the reason why I guess the data lines are involved... what is the function of the Schottky diodes there? They are between reset input and these 3 data lines.

Yes, main power input is 24V. Engine model is old 16V2000 (1500 kW). I have checked power supplies again, they are present and clean: +5V (x 3), +15V and -15V. Any other idea? I know it´s really difficult so if I´ve checked the EEPROMS working on another ECU and I have power supplies correctly may be I have a problem on some processor data communication buffer IC or the processor itself, that´s why I asked if is possible to replace the processor by a new one or it has some basic software programmed inside.

 

[dr pepper]

Ok getting deeper.

It does look as though the 3 schottkeys are connected to the data bus, however I'm not certain as its difficult to read the legend, it looks like D then a number indicating its a data line.
The lower half of the diode chain isnt connected which doesnt make sense unless its a dual diode package and only the top half is used, and even then connecting a dataline to a reset input doesnt make sense.
I looked at the chips datasheet, there is no program storage aboard the device, however it does mention a time processing unit which operates independant of the cpu, I couldnt tell for sure where the tpu gets its instructions from, whether its setup via the cpu or it has its own memory, I'd say at a guess that the tpu is setup via the cpu at startup.
Also there isnt a obvious programming voltage or data/clock pon on the processor so it doesnt look as though it has stored data within itself.

There was a larger diesel at one place I worked, it was a deltic, by your standards positively archaeic, it was way before ecu's of any kind, the o/p was similar to the mtu, probably a bit simpler to repair, though there were times specialists had to come out to it.

 

[2PAC Mafia]

Thank you for your time. Yes, the dual diode is in the same package sot-23. I don´t know the function of them there, they are connecting data lines to reset, D0 (0 bit boot), D8 (port E default input) and D9 (IRQ Disable).
So I have the option to replace the microprocessor after checking deeper all pins because probably all software is at EEPROMS. I couldn´t go deeper because I had other jobs to finish also.

On the other ECU which also had some kind of problem I found a power supply problem on a 5V line, MIC2920A failing and only 1,2V at its output. I´ll replace it.
But this ECU with the booting problem is confusing me because I´m not sure about what is involved in the booting process...

I don´t know Deltic, before having my own electronic company since one year ago I was working for 9 years at MTU official service as electronic chief, but always replacing units and never going deeper on electronics (MTU don´t allow to repair units) which I don´t like. I like to work on PCB´s and repair them if possible, that´s the philosophy of my company.

 

[ClydeCrashKop]

I like the way you think.
My boss just got 2004, 86ft Hatteras with a pair of those engines.
They said they will send me to school on them.
Where is a good place to find technical info?

 

[dr pepper]

looks like your on your way to fixing it.

The data bus is more like a port, and it looks like they are using those outputs as a error check and resetting the chip, I would have said the roms might have been corrupted but you have checked those so maybe the chip itself is to blame.

The deltic was most popular in locomotives, however there were a few marine examples (torpedo boats), its a opposed piston engine with no heads, the cylinders are in 3's and arranged in a delta formation hence the name, its a 2 stroke with a semi fluid coupling on the blower, junkers tried to get it work way back, but in the 60's napier got it to work by reversing the direction of the bottom crank, they were a good engine but really bad to start.

 

[2PAC Mafia]

Hi Clydecrashkop,

if they send you to a training place probably there they´ll supply you some manuals about it. I´ve been at trainings in MTU Friedrichshafen about all different electronic systems they have manufactured.
This system is an old one, later came modern series with modern control and monitoring systems to use with those type of engines.

May be you can find some pdf at Internet about MTU, but not a lot of things.

Thanks, Dr Pepper, I will keep you updated if I have some progress.

 

[2PAC Mafia]

Hello,

finally after getting some processors from China and replace it ECU started correctly!!! After simulating and checking with laptop the speed demand I saw it is also failing which was the original complaint from captain. I followed the signal and I think HCPL7800A is damaged at its output.

I only want to explain it as you tried to help me, so thanks a lot.

 

[dr pepper]

Excellent, do you you'll be able to fix it?

There are specialist companies in the UK too that sell obsolete parts.

 

[2PAC Mafia]

Yes, I have to replace the HCPL7800 to be sure the problem is solved because it creates a signal itself between pin 6 and 7.