Biomass Boiler not driving cleaner motor relay. ENERTRES BIOMASA BI-650

[edugimeno]

Hi everyone!
I have this board that suddenly stopped supplying power to an output that drives an interchanger cleaner motor.
I checked while the board was in place with all wires attached and there's no AC voltage on the corresponding plug X5
This X5 is driven by fuse F8 (tested OK) which comes from the second orange relay
To make sure there are no charcoaled contacts inside the relay, I got a 24VDC power supply and got it ready to manually power up the coil side of these relays.
I respected the polarity, positive to cathode of protecting diode
So provided all the positives to all coils are common, I soldered + to this rail, and then applied negative to the other side of the relay coil.
With the first relay (not the faulty one), it clicked correctly on and off several times according to each time I touched it
With the second relay (faulty output), it clicked slowly and like "lazy" both for ON and OFF (some delay) and I got some smoke smell right away. Turned the board upside down and felt heat around both small Q's that drive this coil.
Can I have damaged the Q's that drive it? As the polarity is granted, they are all going + - + - + -....
Or is this just a sign that these transistors were the culprit for this issue?
I don't really understand the schematic (see images) for the driving Q's, it's like 2 different lines can drive independently the negative side?

Any help would be appreciated!
Thanks in advance

[edugimeno]

Oh also I can see in my own pictures.. .that the second Q at the second relay is burnt by the end of the letter W...And I measured resistance from E to C in this transistor and it has 30 ohm on both polarities, which is not happening on all the other Q's
Should I just replace this Q?

[edugimeno]

Anyone? Thanks

[petehall347]

yes replace relay driver and check the flyback diode

[truclacicr]

http://markingcodes.com/search/c/1gw

1GW = BC847CW or BC847C

[edugimeno]

Yes I have 5x BC547C ordered at the local store, arriving next week.
Will see how I manage to desolder/resolder them, Im not very proud of my smd soldering skills...neither my sight

[petehall347]

good magnifier with light. and hot air works a treat .

[edugimeno]

And does it sound reasonable that feeding 24V to the relay coil pins (correct polarity) the transistor started to smoke? Is this a hint that the Q was already blown?

Also can I have damaged any other electronics before the transistor driver (like an IC) maybe getting these 24V to get back to the IC?

Thanks

[edugimeno]

good magnifier with light. and hot air works a treat .

I will prpbaby get one of those magnifiers with a weight. I don't have hot air, only a gas powered soldering iron that has a point for hot air, but having some other tiny smd R's very close, I tend to belive that with hot air all the stuff around is going to get loose

[petehall347]

I will prpbaby get one of those magnifiers with a weight. I don't have hot air, only a gas powered soldering iron that has a point for hot air, but having some other tiny smd R's very close, I tend to belive that with hot air all the stuff around is going to get loose

i dont have trouble with components this size they are pretty big compared to the real small ones . thing is with an iron its difficult to hot up 3 legs at the same time . what i do is add new solder with my iron then hot air .

[edugimeno]

i dont have trouble with components this size they are pretty big compared to the real small ones . thing is with an iron its difficult to hot up 3 legs at the same time . what i do is add new solder with my iron then hot air .

Suppossedly flux around would help getting the heat spread around the whole transistor, that's my hope...Will see when they come