Mechanical or circuitry problem?

[andoru]

Hello, first time poster here =D
I've been having some problems with a Senseo coffee machine that recently has been acting up. For some reason while it boils the water or it pumps it through a vent at the bottom of the water container it shuts off.
I've read many places that typically with this machine that's an indicator the pump is malfunctioning and needs to be replaced. But there has been another person who suggested that a capacitor (470nF X) must be replaced, but hasn't given further details.
So now onto with the noobish questions I wanted to ask you guys:
I haven't noticed any damage on the PCB (other than some stain at the bottom of the PCB, near the "heatsink") or on any on the soldered components, how am I able to check if the traces aren't damaged or there's some problems with any of the components (capacitors, resistors, etc.)? Would a DMM be enough and how would I use it to indicate me any problems?

I'll attach some photos that I took of the innards, although I'd think it would be quite useless for you guys in this case. Sorry for the shoddy camera work. If you need any more detailed photos I'd be happy to take more.

I chose this as an electronics project just for the fun of it, and also to not give in to the capitalist way of going out and buying another coffee machine =P

[andoru]

By pad you mean the "heatsink"? I really don't know what's it purpose other than that, a microcontroller apparently rests on it.

I'll try to get a photo ASAP and append it to this message =)

[andoru]

Thank you for replying and sorry for my late one =)
I have tried to take some more photos, but my phone's autofocus (which I can't control) is rubbish, but I took a good look at the solder you pointed out and found out it is properly soldered on the board and it's not lifted off. It just seems to have some sort of a dark lining around the solder blob for some reason. I attached the best photo I could take that shows it's mounted on the board. I also took a photo of the terminals to the said component on the other side, just in case.
Also I was wrong, the component that rests on the "heatsink" wasn't a micro controller, it's this: http://www.nxp.com/documents/data_sheet/BT139-600E.pdf
I have a suspicion that might be the cause of the whole shutting down issue due to the "voltage blocking" part of it's sheet. But then again I'm just a noob =P
Also that residue around the three solder points is very suspicious, looks like dried salt water, or dried limescale laden water. But I assume that might have been some residue from the soldering or they applied some sort of coating? 
If you need any more info about the chips on it, I could look it up. It's very difficult to read the small text on the chips.

[rexxar]

That triac is probably for the heater, and if you say it's still boiling water, it should be fine. I'd take a look at the pump, see if there's any sort of blockage, or if you can get it to spin up from an external power supply.

[minime72706]

I hate it when pretty well manufactured PCBs are ruined by hand-soldered components. They used epoxy and everything!
Do you end up hearing the pump run at all? If so, does it sound normal? You say it also fails when merely boiling water?

X2 capacitors are pretty damn sturdy and I also don't see it causing the symptoms you have. I'll gladly send you a replacement since I have a few dozen kicking around, but I think the issue is elsewhere.

The grossness around some of the larger solder pads is going to be some sort of flux residue from hand soldering. Not much to worry about.

The BT-series TRIAC is almost certainly, as rexxar said, controlling the heater. A TRIAC works by blocking current flow until a trigger signal is applied to the gate. It then conducts AC current until the next zero-crossing of the voltage. Unless it is continuously triggered or held on by a long pulse, it will only conduct for a half cycle (roughly 8.3ms maximum) before shutting off, assuming it's operating normally. Resistive heaters are exactly the kind of load that a TRIAC likes seeing. I imagine the TRIAC is fine.

If you've never heard the pump start up properly in the current functional state of the coffee maker, it's almost certainly related.

[andoru]

That triac is probably for the heater, and if you say it's still boiling water, it should be fine. I'd take a look at the pump, see if there's any sort of blockage, or if you can get it to spin up from an external power supply.

Thanks for clearing that up.
I'll try and see if I can power the pump, but wouldn't I need some way to control it? Also do I have to strip the pump from it's cables? I'd assume that would send the current through the whole circuit and cause trouble.
But about the pump: the machine has a drain mode when it drains all the water out of the boiler, and I'm quit positive the pump is working properly during that. When I would drain the coffee machine, it stopped less frequently and the interval between power-up and interruption was a lot longer than when going through it's brewing cycle. Also what I noticed is that when I don't leave any pods in the machine (it just spewing out hot water) the same thing happens (less frequent shutdowns) so I'd think the problem would be at sensor level as TheSolderShack said. =)

I hate it when pretty well manufactured PCBs are ruined by hand-soldered components. They used epoxy and everything!

Hey, at least it's made in Poland, not China =D
But just out of curiosity, is there any detrimental effect but soldering manually?

Do you end up hearing the pump run at all? If so, does it sound normal? You say it also fails when merely boiling water?

The sounds the machine does are normal, whether it's the boiler or pump, I don't know. But I explained above how the shutdowns happen =)

X2 capacitors are pretty damn sturdy and I also don't see it causing the symptoms you have. I'll gladly send you a replacement since I have a few dozen kicking around, but I think the issue is elsewhere.

Here they are quite cheap as well, but thanks for the offer.

The grossness around some of the larger solder pads is going to be some sort of flux residue from hand soldering. Not much to worry about.

That's good news at least.

The BT-series TRIAC is almost certainly, as rexxar said, controlling the heater. A TRIAC works by blocking current flow until a trigger signal is applied to the gate. It then conducts AC current until the next zero-crossing of the voltage. Unless it is continuously triggered or held on by a long pulse, it will only conduct for a half cycle (roughly 8.3ms maximum) before shutting off, assuming it's operating normally. Resistive heaters are exactly the kind of load that a TRIAC likes seeing. I imagine the TRIAC is fine.

Thanks for the details, love 'em =D

[minime72706]

I addressed your question regarding my dislike of the stray hand-soldered components in another post you referenced. They just tend not to bother cleaning the flux and they're ALWAYS lazy. In some small way, they're lazy. Even if you can't see it!

[andoru]

@minime72706: I think you might confuse me with somebody else? Or perhaps I didn't get what you meant to say. You haven't specified why you hare the manual solder job on your previous post =)

Anway, sorry guys for replying so late. I took a look around the house to see if I can find an adapter or such to be able to power the pump, but I wasn't able to. Unfortunately I don't have a power source to give it the exact rate of current it needs. Also not to mention that I don't know how much power I need to give it in the first place... (yes I know, I'm hopeless XD )
But again, I doubt that the pump has any problems, as it was working and it didn't make any sounds that weren't present when it was working normally.