I’m a proud owner of several Mikrotik networking products. Today my CRS310 decided to break. The fan isn’t working anymore due to dead PWM chip, as shown in the photo. This makes impossible for me to run the switch. I bought it on ebay from a previous owner and I don’t know if I’m covered by warranty. The board isn’t touched, never opened and the operation temps were fine before. What can I do? please help me.
Blown up PWM Chip: https://ibb.co/LXB8DJ48
PWM Chip Area: https://ibb.co/1YNVFrQR
Entire board: https://ibb.co/2YmDCYFq
I contacted them and they ditched me, throwing all responsabilities to distributors and the ebay seller won’t help me either.
I’ considering to repair by myself, I need to know the part name of PWM chip. I don’t know where to find it and I don’t have any PCB diagrams. Can someone take apart their switch and take a picture of IC name?
That’s the usual answer, and while frustrating, I can’t absolutely fault them.
Sourcing these parts can be really inconvenient, especially if “at a reasonable price” is in your requirements.
Here’s what I would do, maybe it helps…
Does it run absolutely too hot in your specific use case; if not, why bother
If it doesn’t, one reason why a PWM controller fails is if the fan has failed as a short. Does the fan run nominally if fed from an outside PSU?
Connect the fan to the given voltage directly internally, with a resistor/diode/zener to limit it to some acceptable RPM. Of them you have to take care that the parts aren’t overheating.
And when I look at the components around it’s DC-DC converter. If you are going to repair it yourself be careful because there must be a reason chip blew up. So replacing it with a new one could result in another blown up.
Also this is very tiny smd so if you never done that find some electronic repair shop to do it for you.
Yes, you need to find out first WHAT caused the issue before replacing the chip.
That kind of “chip explosion” is actually quite rare, usually they just show some sign of over-heating, as lurker888 stated it is likely that it is the effect of an excessive current going through it (I remember those kind of blown up chip on some old hard disks PCB’s when the spindle was seized).
If the device actually works fine, I would think of getting an external fan controller, they can be found for a few Euros, connect it to the 24V power supply through a 24V-12V buck converter (another handful of Euros), connect the fan (after having tested it) to the controller and call it a day.
This kind of explosion indicate there was high energy fault, maybe overvoltage on the input, or maybe wrong polarity connection but i believe that Mikrotik have proper input protection in place.
Can you test the fan on 12V supply to check is it working ? Black is GND, Red is 12V, Blue is PWM signal (you connect this wire to 12V for full speed)
With power circuits it’s rare that PWM controller goes bad by itself. Other components around it should be checked as well.
Perhaps not really helpful, but if there is enough room around the switch I’d suggest to put a 80mm or even 120mm slow running fan on top of the device and ditch the small noisy 40mm fan.
It is defectivy anyways, so you can improve the product.
sorry for my late answer but I don’t have push notifications. I’m very thankful to all, gigabyte091 gave me a important detail about the incriminated chip. Temporarily Placed an external fan powered by 9v, a very ugly but functional work. (the original fan was working). Yeah, I think I buy the brand new chip and some spare and I’ll send to a repair shop that works on PCBs. thanks again!