Repairing a PCB ( and posting photos)

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pcatterall

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Well it doesnt look like a photo to me!!
Trying to post a photo of a damaged circuit board from my Webasto Thermo Top C heater.
Are there people who still repair these things? There is clear damage to the black chip thingy in the lower right of the photo, in the old days our 'elec tech' would just solder in a new one!
The heater was bought new ( but on Ebay) to be fair it did work but when it came to testing pre installation it didnt.
I dont think it has been dropped or anything in the workshop and am at a loss to see how such damage could occur.
The 'black thing' may control the blower fan as there was some intermittant working prior to it giving up altogether.
Can some kind person......
Say if my photo has worked
Say if it is possible to replace just the companant
Guess how that damage was caused
Tell me what that sort of componant does ( I see 2 similar ones on the board)
 
Hi,
Rather nice photo! Have you tried contacting captainslarty??? he seems to be rather knowledgeable about these electric thingies??? try him............ /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif
 
[ QUOTE ]

Are there people who still repair these things? There is clear damage to the black chip thingy in the lower right of the photo, in the old days our 'elec tech' would just solder in a new one!

Can some kind person......
Say if my photo has worked
Say if it is possible to replace just the companant
Guess how that damage was caused
Tell me what that sort of componant does ( I see 2 similar ones on the board)

[/ QUOTE ]
In theory it is possible to replace the component but.....
a) it's a highly-skilled job
b) it could damage the board beyond repair anyway by damaging the tracks
c) it may not be the cause of the problem - the encapsulation is damaged but that does not necessarily mean that the component is dead. I note that there is some superficial damage to the adjacent component which may have been caused at the same time.
 
[ QUOTE ]
It's a transistor

[/ QUOTE ] The obviously damaged component I'm looking at isn't!

I'd be worried that there is heat damge to other components. I'd also be worried that there is a cause for this failure that needs to be identified and rectified quite apart from replacing this one item.
 
You can get diodes, transistors and FETs in packages like that.
To remove a big surface mount package can be done, often using a hot air gun, but may also require pre-heating the board from underneath. Alternatively cut the small leads and use a big iron on the big tab terminal.
I would guess it may have been over-current during test with no fuse in the circuit?
It may even be a 'crowbar' circuit intended to blow the fuse in an abuse situation such as reverse volts or powering from outputs.
Unfortunately there are a lot of possibilities!
Best bet may be another PCB, i regret to say.
 
[ QUOTE ]
[ QUOTE ]
It's a transistor

[/ QUOTE ] The obviously damaged component I'm looking at isn't!

[/ QUOTE ] What do you think it is?
 
lw395 comments were interesting ( and everyone elses as well !!) I only used a battery to test so I cant see overvoltage. The damage looked physical to me, the broken off chip of the device was in the compartment. If a device is fitted to protect against wrong polarity etc then why would it be on the main PCB board where it is so difficult to fix?

There are many advocates on this forum supporting Webasto over Eberspacher. At this time I have to say that the electronics on the ebers seem much better protected than on the Webastos ??
And come on guys is it a transistor or what and ( for interest what does it do??
Thanks, all for the comments to date.
 
My first thought was a voltage regulator, but I don't want to fight about it.

Whatever it is the real question is whether the damage to it is cause or effect.

It could well be something like a capacitor that has failed which has caused the 3 legged monster to overheat.

The damage does look like overheating.

I would say first step is to identify the damaged thing, and then try to remove it and establish if there is any other cause or effect of the damage.

I suspect simple replacement may result in destroying the new bit.

If you can get a diagram it would be a good first step.

Trouble with these things is the labour cost of diagnosing and repairing them is likely to esceed the replacement cost.

Best of luck anyway.
 
I suspect the whatever caused this is external to the box.

it could either be:-

the control transistor to the blower motor, so the blower might be duff.

or the control for the glow plug, so the glow might be duff.

Either way, repair is easy if you have the right equipment, difficult if you don't.

try removing the varnish on the component & on the others bottom left on the photo, compare any numbers to see if they are the same.

However, you have to find someone who will do the repair, who will charge for his time. You may find webasto do an exchange service, at a large price, but they do have you by the goolies............
 
No no burning smell. The splattering was, to me, reminiscent of days when our elec techs first check (after sniffing!!) was to poke each componant to see if there was a dry joint problem ( this was in days before joints had another significance)
I thought that if someone would just replace that componant then there was adprospect it would solve the problem, if it didnt then replacement would be the way.
Thanks once more.
 
I'm afraid I'd just roll over, come clean and write to Webasto sending the picture and asking if they can help, and for how much. If their replacement board is less than you thought, then that will almost certainly be the best route. If its more than you thought then you can take stock and try a repair. It may be a substandard component for all you know.

Sometimes people are helpful. I have a Praktica SLR I bought in a second hand shop over 20 years ago. It had a metering fault, and was just out of warranty. I wrote and asked and they fixed it for the cost of the postage. Its never gone wrong since.

Worth a try. Anyway..if its new it has a warranty anyway surely, regardless of whether its an ebay purchase or not.

Tim
 
It's not really a case of can it be fixed. The easy answer is yes it can. The real question is can it be fixed economically. The problem intimated by others is why did it blow in the first place? This could be any number of different components: transistor, diode, reguator etc. The question is really what's wrong with the whole thing and that takes far more effort & knowledge than just replacing the part if you can find out what it is.

What is certain is that this a quite a high power part. It could have just blown. But in blowing, it could easily have taken out a whole load of other bits. Alternatively, something else could have blown causing this to blow.

Also the board is covered with a conformal coating. This is there to protect against corrosion in a harsh environment. To do a proper job, it will have to be cotaed again over any repair.
 
Ok its got three legs, is connected to fat PCB tracks. Its probably a MOSFET. It probably costs about £3.00 max.
It probably blew up because:
It was subjected to static electricity (unlikely while wired in)
Somebody disconnected the battery with the engine running.
The boat it was on was nearly hit by lightning.
The battery connection was loose when you were testing it and the rapid changes of voltage and current caused a too high voltage to appear.

It will be hard to remove - of course you can grind off the plastic with a Dremel and then get a soldering iron to the metal tab under it .

To identify it - I would carefully scrape the black paint off the two similar devices on the lower left. I think they are likely to be the same type.
But its a challenge probably ending in failure .....
 
Hmm.. yes, probably a fet ...

you need to remove it first.. check the supply snd terminal voltages.. if it looks ok, then replace.. firstly though... as others have rightly said.. WHY did it go pop.... you also need to do the same test on the external components...

Doesnt look too much of a problem at first glance.. but likely the fault is OFF the board.

Joe
 
Great photo.

Damaged component looks like a transistor to me. Difficult to imagine how it could sustain mechanical damage sufficient to break it without other bits of the board being affected too. Most probably overheating, perhaps due to the failure of some other part of the circuit.
Anyway, even if you could identify the part and obtain an exact replacement, and even if you could fit it without trashing the neigbouring components, you don't know what caused the original problem or if any other components have also been damaged. I'd give it up as a bad job and try to obtain a complete new circuit board from the manufacturer.
 
Ang on guys!! lots of you say the problem may not be due to that componant so replace the board; fine, but if it is external to the board then I may ruin yet another one!! Or am I misreading something?
The unit has never been fitted anywhere, just possible there was some on/off contact when I connected it to the battery as there was no switch installed.
Thanks again for all your views and advice.
 
The device is obviously a power semiconductor ie a transistor Field Effect Transistor, Silicon Controlled Rectifier or Voltage regulator chip.

It has obviously been overloaded by voltage or current through it causing it to explode from internal pressure. Unfortunately the face that had identification has been blown away. It would not be safe to assume it is the same as the other similar packages.

The reality is that modern components are incredibly cheap but incredibly expensive (risky) to replace on a board. Such that as already said your chances of fixing it are very near zero.

I once was a professional fixer of electronics and I really enjoyed finding the faulty component and replacing it. But the business has all changed and I am fortunate to have had a career change to get away from that business.

As an example my little Etrex GPS. The manufacturer won't even consider a repair or opening the box he simply offers a discount on a new one. Garmin know they can't be fixed. (If it is not fixed by software update.)

Sorry get used to the new world of electronics. Cars will be the same soon. (if not already in the elctronics) olewill
A new board is almost the only way you will solve the problem. But do make certain there is no external fault that caused the damage.
 
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