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Question about processors

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2PAC Mafia

Member
Hi guys,

I have a doubt... I´m trying to repair an industrial marine computer which has a problem, screen is not switching on and I guess there is a problem at processor board, it´s a Kontron processor board. When a measure at drain-source of 42N03S mosfets near to the main processor I get short circuit. I only could remove one and out of the board is good.
Processors are in BGA format so not a lot of things to measure, but I remember I already had a similar problem where when I measured at some electrolitic capacitor I got short, when I removed the processor from a socket the short dissapeared so I thought the processor was in short. I replaced it and the problem was still present. Finally the problem was another thing not in that board!!!

My question is how or why this power source measured at SMD capacitors or even measuring mosfets is giving shortcircuit and when the processor is removed the shortcircuit is not there anymore.
 

2PAC Mafia

Member
It´s from monitoring and control system from a pleasure yacht.
 

dr pepper

Well-Known Member
Most Helpful Member
Clock driver circuits in processors are designed to drive high capacitances and low impedances, this maybe your low reading, still a bit unusualif the chips not powered.
Also the i/o of a microcontroller or processor with i/o will have protection on the output pins, this will give you a low reading.
Try the test again and this time with the meter set to diode drop, if you get 600mV or thereabouts no problem, zero ohms then that could be something wrong.
If your measuring across the power pins maybe your meter is trying to power the circuit, and thats not going to give meaningful readings.
I'm glad my boat doesnt have electronic engine management, its a good old fashioned cav injector pump & pintaux injectors.
I know a little about Abc, jm, and napier engines not from the marine industry, from generators.
 
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2PAC Mafia

Member
Thanks for the explanation Dr Pepper, very difficult to work at these multilayer processor boards...
 

earckens

Member
I presume your clients are not on welfare, therefor I would not waste time trying to repair anything but just replace and charge accordingly. Sounds right?
 

2PAC Mafia

Member
I presume your clients are not on welfare, therefor I would not waste time trying to repair anything but just replace and charge accordingly. Sounds right?
First of all I wanted to know more about these strange measurements on processors. On the other hand, my job is usually to repair, that´s my trick to have my company running, for changing boards there are enough people around the world.

In this issue, the board is obsolete, I found used and refurbished units by 4000$. Manufacturer of the industrial computer can supply this internal board by 10.000€, so in these cases with these prices is good to go deep of the unit and always try to learn something new in case the repair is not successful.

Sometimes I repair 10.000€ units and sometimes I repair 150€ units, but my deal is to repair electronics.
 

dr pepper

Well-Known Member
Most Helpful Member
Yes I sometimes spend a day repairing 'junk' like an old crt video monitor to get it working, when in actual fact it has a negative value as it would cost to dispose of it.
But when a production line is stopped with everyone waiting because the monitor is dead you have to get it going.
 
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