Something went pop.

[KAM]

I was fault finding the alarm panel on my Yanmar 3YM30. It's called an alarm panel because replacements cost €700. It looks like I've blown surface mount resistor. Anyone know how to identify these. I was just wondering why there are more components than shown on the circuit diagram. A new one is out of the question. Looks pretty simple to emulate. Does anyone manufacture a generic warning light buzzer panel or can anyone point me in the direction of a suitable circuit diagram.

 

[wonkywinch]

Since all the alarm circuits are duplicates, are you able to reverse engineer it and measure an intact component?

 

[penfold]

I don't see any obvious smoke escape from that; where do you think has failed? The resistors are 620 ohms according to the marking. What's on the other side?

 

[KAM]

I think it's the charge light circuit. There's only one. I accidentally shorted it to earth. The other side of the board is blank. I don't think it's a multilayer. I presume the components are to drive the LEDs from 12V. Replacement price is totally outrageous.

 

[penfold]

Left to right you have what I think are 3 transistors, two diodes, 4 LEDs and a capacitor, then 9 resistors. Which do you think has had the smoke escape? I can't see any gross signs of damage but the pic is a bit fuzzy.

 

[KAM]

It must be something associated with the charge light circuit or maybe a couple of common components that drop down the 12v. I'll have a look under a magnifier. It was definitely a pop and the board is now not working. All's well with everything else.

 

[rogerthebodger]

I tale it you did check the 3 A fuse that feeds the LED circuit

 

[KAM]

Yes the fuse was fine.

 

[penfold]

In the extreme it's a very simple device; it could be replicated using stripboard. I'm assuming the 700 yoyos is for an entire control panel with ignition keyswitch, alarm, idiot lights, a tachometer and temperature gauge?

 

[Boater Sam]

You have some poorly soldered connections on the left to the connecting pins on the other side. They look like cracked dry joints.

 

[penfold]

You have some poorly soldered connections on the left to the connecting pins on the other side. They look like cracked dry joints.

Certainly wouldn't hurt to reflow that row of 6 terminal posts.

 

[bedouin]

Left to right you have what I think are 3 transistors, two diodes, 4 LEDs and a capacitor, then 9 resistors. Which do you think has had the smoke escape? I can't see any gross signs of damage but the pic is a bit fuzzy.

I think those "transistors" are in fact diodes - not sure why they have three "connections" but you will see from the empty spaces that only two of the pins are connected

 

[KAM]

Not sure what 700 yoyos are. It's only the charge light, over temp switch and oil pressure switch the 4th indicator is for water intrusion which is not connected. Totally baffled why the replacement costs so much.

 

[KevinV]

These two spots might be worth a look - it looks like a hot wire may have shorted these - a scrape with a scalpel would sort this out.

 

[penfold]

I think that's just a reflection off a blob of conformal coating, but worth the OP checking.

 

[KevinV]

I think that's just a reflection off a blob of conformal coating, but worth the OP checking.

Ah, okay, I see what you mean now

 

[KAM]

Yes the coating is pretty thick. Makes fault finding tricky.

 

[Alex_Blackwood]

Instead of all the speculation. It might be helpful if we knew what, exactly the OP was doing when it went "POP" What "test kit" where exactly he was using it and how. Then all the bits of info. that are unimportant and don't matter, but might just be the clue!
Depending on what he was using I suspect that it is unlikely that a resistor would blow, for example. That just about leaves the three diodes and the LEDs.
There is also another component, below right of the diodes, which I can't ID. Edit +2 others at the bottom of the board!

 

[Boater Sam]

Instead of all the speculation. It might be helpful if we knew exactly the OP was doing when it went "POP" What "test kit" where exactly he was using it and how. Then all the bits of info. that are unimportant and don't matter, but might just be the clue!
Depending on what he was using I suspect that it is unlikely that a resistor would blow, for example. That just about leaves the three diodes and the LEDs.
There is also another component, below right of the diodes, which I can't ID.

One end of which must be attached to something on the reverse side of the board.

 

[bedouin]

Instead of all the speculation. It might be helpful if we knew exactly the OP was doing when it went "POP" What "test kit" where exactly he was using it and how. Then all the bits of info. that are unimportant and don't matter, but might just be the clue!
Depending on what he was using I suspect that it is unlikely that a resistor would blow, for example. That just about leaves the three diodes and the LEDs.
There is also another component, below right of the diodes, which I can't ID.

Blown diodes would stop the buzzer sounding but not the lights coming on.

It is a very simple circuit with no common components - knowing which parts work and which parts don't would help isolate the problem. If nothing works it has to be a power supply problem