Hello, I'm not educated in electrical background so I may not understand a lot. These 2 photos attached are Flasher Sign Relay module for same Trucks model. Could you guys teach me what is the differences of quality in both products? Thank you very much

 

Welcome to AAC.

They are both cheaply made boards, but, the first one has fewer components, open relays, and what appears to be an inferior PCB substrate. All of which suggests severe value engineering. In value engineering products are designed to a price.

Not always the lowest price but in this case is appears to be the case. This means it will probably have a shorter life and be less reliable in operation.

Some particulars:

This component is an op amp IC. The left one is from the first board and is from an unknown manufacturer while the right on is from a reputable one. There may be nothing wrong with the left one, but it is suspicious.

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This component is a high wattage resistor. That would be used in cases where more current is expected to be handled. The reason they are larger is to handle heat, because heating up is an inescapable side effect of handling power. The one on the left is from the cheaper board and it definitely gives the impression of being a lower quality, less expensive part.

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There are other things like the presence of components on the second board that aren’t on the first. Several resistors, capacitors, a diode, and what appears to be a transistor. The large cap, diode, and transistor in particular are relatively expensive parts that would not be simply added to the design. They must serve some important purpose which the value engineering of the first board eliminated at cost of function, reliability, and durability.

 

Welcome to AAC.

They are both cheaply made boards, but, the first one has fewer components, open relays, and what appears to be an inferior PCB substrate. All of which suggests severe value engineering. In value engineering products are designed to a price............

Thank you Mr Ya'akov.. These are indeed cheap quality ones distributed in my local intended for low price products. Thank you so much for you analysis! May I have your opinion on the main component? Do they use different methods in the main components?

 

The quality of the circuit boards is probably similar, the one with the open relays is a bit suspect because of the way they are mounted so close. It might be a mechanical set/reset scheme. I have seen that done. And that same board uses a open wire resistor, not protected in any way. It works but it is not a good design, nothing is protected from short circuits or physical damage. Do they mount in an enclosure?

 

The quality of the circuit boards……….. It works but it is not a good design, nothing is protected from short circuits or physical damage. Do they mount in an enclosure?

Yes they do have enclosure.. these two I got from opening their case.. Thank you for your analysis MisterBill2. As you said, I do find trouble more in using the open relay one

 

Even when I examined the close-up photo of the open relay arrangement it s not clear if the two relay devices are in a latch/unlatch arrangement, or if they are simply mounted very close. So I am wondering about that, do they function in a latch/unlatch manner?
Also, that open wire does not appear to have any electrical connections below the PCB, so it might not be a resistor like I had guessed. Does the TS see any electrical connections to it on the solder side of the PCB?? If not, what is the purpose of that wire??

 

Even when I examined the close-up photo of the open relay arrangement it s not clear if the two relay devices are in a latch/unlatch arrangement, or if they are simply mounted very close. So I am wondering about that, do they function in a latch/unlatch manner?
Also, that open wire does not appear to have any electrical connections below the PCB, so it might not be a resistor like I had guessed. Does the TS see any electrical connections to it on the solder side of the PCB?? If not, what is the purpose of that wire??

At a guess, a standoff to keep the housing from being compressed against the relays.

 

By open wire, do you mean the square-wave looking shunt? That's a current sense shunt, it connects one of the off-board terminals to the lower relay, it's the same as the shorter, straight shunt on the other board. They would both be used by the op-amp for current sensing I would expect. I would think that it is longer (and so probably a higher resistance value) on the second board because they use different op-amps and the current sense voltage may be set differently.

 

By open wire, do you mean the square-wave looking shunt? That's a current sense shunt, it connects one of the off-board terminals to the lower relay, it's the same as the shorter, straight shunt on the other board. They would both be used by the op-amp for current sensing I would expect. I would think that it is longer (and so probably a higher resistance value) on the second board because they use different op-amps and the current sense voltage may be set differently.

That’s what it looked like to me initially, but it seemed overly complex given how tightly controlled the BoM appears to be on that board, using so much large gauge wire and having to form it appeared off. Maybe it is a shunt and mechanical support.

It can‘t be handling so much current as to need such a large diameter (see the other board, which seems to be much more willing to spend on BoM, e.g.: higher wattage resistor, active component, more passives, &c).

 

I did initially think that wire was a shunt, but I did not see connections to it and so I then presumed it was not a shunt. But that was my first guess. I saw no shadows in the PCB image.