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Dude, replace that power transistor and motor on. Should cost less than the diesel it take to go get it at Radio Shack.
A short in the load may have drawn too much power, so buy 2 resistors in case the short condition causes another failure!!!
Look the board over closely for any further damage or loose pins. Button it up and see if it works!
Could be the driver for the solenoid operating the shut off butterfly on the intake???
Thanks guys, I'll have to start her tomorrow (if it will) to see if it will shut off. Couldn't find anything in the FSM about an Air Control Relay. This HJ also has A/C, but according to ngiri, it's listed under the EDIC, which of course the auto doesn't use. Perplexing?
Most likely the driver transistor for this transistor is blown also, do check as you could overload the Base pin on the 2SD571 if this is shorted. Replace the electrolytic can capacitor, don't bother testing it, with a 105 °C rated part.
2SD571 datasheet pdf datenblatt - NEC - NPN SILICON TRANSISTOR ::: ALLDATASHEET :::
Why replace the Cap? I seldom see failures, they are kinda off to the side electrically.
Electrolytic caps are actually the main cause of failure in electronic equipment. When servicing electronic equipment and you replace something like a transistor, you always replace the associated caps, if you don't, the job will most likely come back to haunt you at your time/expense and you will also have an unhappy customer. A typical electrolytic capacitor has a lifespan of 2000 hours at its rated voltage/temp. To fully test an electro you need to do 2 tests, one with a capacitance meter (finds about 10% of faulty caps) and another with an ESR meter which finds the rest. If you know what you're doing you only really need the ESR meter, I hardly ever bother with the cap meter if I bother with cap testing at all. Most technicians won't even bother testing caps unless they are fault finding, they just replace the associated caps. Your time fault-finding on the bench is worth far more than replacing a few cents worth of caps.
That cap is old and only worth a few cents, so it only makes sense to me to replace it and be done with it.
rockcrawler, I think I can learn something here.
I understood Capacitors function as current storage/buffers in an electronic circuit. (think of a pulsation dampener in hydraulics) Are Electrolytic caps somehow different than other caps, or is my understanding of the use of capacitors incorrect?
An electrolytic cap is made up of two strips of (usually) aluminum foil sandwiched between some paper and rolled up and put into a can. This is filled with a liquid called electrolyte which provides the electrical isolation medium between the aluminum plates. The can is then sealed with a rubber stopper through which the leads pass through. The problem with this is that the electrolyte dries up over time causing the cap to start acting like an AC resistor (thus you need an ESR meter to measure this AC resistance). As the electrolyte dries it produces gas causing the rubber seal to start leaking electrolyte. All this is compounded by the resistance producing internal heat perpetuating the problem. As circuits are finely tuned machinery, this can cause voltages and currents to rise above the specs of the parts causing failure, or in the least, cause incorrect operation. For instance, with CRT based equipment (monitors, TV's) the switching power supplies are basically current pumps, depending on demand the current storage caps are charged faster or slower. The reason for this setup is energy efficiency. Given that that there are electrolytic caps on the oscillator of the pump and that as these dry the frequency of the pump increases, the whole working voltage of the circuit keeps increasing until it fails. Most equipment these days use switching power supplies and the root problem is usually electrolytic caps.Please walk me through the various failures of Electrolytic caps and point out how they can pop a driver.
Absolutely, especially in this case.When looking for the cause of the driver failure, my experience would have me looking first for a short in the load circuit, causing too much current flow through the driver.
I'd say most problems with electronic circuits, especially ones that generate some sort of power and heat, is caused by the circuit itself, but I would certainly look at the state of the load before anything else. If the problem is not complete failure, I normally isolate the problem area by disconnecting it from the load or next system unless the cause is obvious.Your posts indicate you look at the line current operations. I'm curious as to your reasons for this difference as well. Or maybe you also find a shorted load causes popped drivers AND other line damage, like caps and resistors???
.....this can cause voltages and currents to rise above the specs of the parts causing failure, or in the least, cause incorrect operation.
Don't forget though, a shorted cap or other component can cause the same symptom if its connected at that point.
I'd say most problems with electronic circuits, especially ones that generate some sort of power and heat, is caused by the circuit itself, but I would certainly look at the state of the load before anything else. If the problem is not complete failure, I normally isolate the problem area by disconnecting it from the load or next system unless the cause is obvious.
edit: by the way Rick, my original post on this was in addition to your recommendations, all the things you mentioned must of course be checked also. I should have made this clearer.
I'm not clear on this point. If the cap is before the driver, then the cap will make smoke and open the circuit. If its after the driver, it will allow higher current flow through the driver and the driver goes bluey, correct?
Yes, if you are going to make money out of a business, or if you are employed by someone to carry out work, in either way you will have to home in on the problems rather quickly or you will be out of work. I realize that with the internet there has been an apparent rise of IQ and a whole heap of "experts" have come out of the woodwork. However I think it would be a mistake to think there aren't any people around that do know something about the field they claim to be knowledgeable inNo worries, mate, I appreciate your apparent experience and thoughtful posts. As a former professional, there was a lot of pressure to make rapid and effective repairs. Shop/business practices prevented us from opening electronic assemblies to see what could be done to repair them. As a result I didn't get too many opportunities to delve into electronics, and I appreciate someone like you who apparently has.
Here's the update: This will be good knowledge for those who believe that just because a diesel is turning over it should start. I could not start the 2H without this relay plugged in, obviously it controls the VSV. Without this inline the VSV keeps the butterfly closed, so no start. Plugged her back in and all was well. I didn't unplug the relay with the engine running for fear of a ground arc/fault, but I'm pretty certain that the motor would stop. This relay is still functioning even though one of the transistors is blown apart. Could that transistor still be working? Does the board have onboard redundancy? Thanks for the info rockcrawler, I'll be swapping out the cap as well. Just to be clear, it's probably in my best interest to change out both transistors and the cap, maybe also check to see if a resistor failed as well, does this sound solid?
Edit: I believe the reason for this minor explosion was some wiring from the PO. He had tapped into a wire going to the relay and was using it for????
I think it might have been for a trigger on another relay he installed, maybe to allow the stereo to turn on/off with the key. I hate it when people just grab wires randomly to use for this purpose... ARG!