Electronics Fan Controller Help

Got my fan controller today and i rigged it up with a random fan, There was a slight spark and a bad smell I think the fan was a dud and decided to go it's time, it's still fine but the first channel is stuck at full speed. My guess is it's fragged one of the capacitors on the channel, anyone any idea what one? Will i be able to test it with a multimeter at school using the points on the underside of the board? Will the dead cap just show 0 capacitance on the mutlimeter?



Thanks in advance,

Leeum

 

It's more likely the switcher transistor has failed short-circuit. Check resistance between ground and fan negative on that channel and a working one. With the controller disconnected from the supply.

 

Thanks So that's the resistance negative (black) wire on the channel and then ground (somewhere) on the circuit? If so, i'll get that checked at school tomorrow A friend says it could be the VRM that's gone, is that bad?

 

From what look like inductors and the lack of any heatsinks I'm guessing it's a PWM controller. Is there a number on the transistor-looking thingies behind the fan sockets?

Also measure resistance between the 12V line and fan positives.

 

No writing on them but the pins are labelled E, C, B from left to right. This picture might help.



I'll get those resistance values measured tomorrow

 

Is that a Nexus controller? If so, I think the transistor is a PNP, so resistance +12V to fan positive may be zero on the bad channel. Anyway, check both.

Wot you mean no writing? I can see 772? and other stuff.

 

Yip, it was a Vantec Nexus NXP-201, now it's 3/4 of a one Thanks for all your help cpemma, i'll get back with those values tomorrow night. It sounds like it most likely will be the PNP transistor, just hope it's all fixable

EDIT: So there is They say as folow:

H T
772
1KTB E

 

Possibly http://www.alldatasheet.co.kr/datasheet-pdf/pdf_kor/KEC/KTB772.html

It's the same TO-126 case at any rate. And despite what the datasheet says, I reckon it's a PNP from all the negative figures they quote.

 

Ok here's what i found, i had the multimeter set on continuity tester, think it showed ohms not too sure.

Channel 1 - 12V - 12V = 21 ohms?
Channel 2 - 12V - 12V = No continuity
Channel 1 GND - GND = 0.05 ohms?
Channel 2 GND - GND = 0.05 ohms?

I tried the continuity of those transistor things aswell:

Channel 1 - 12V - Middle leg of transistor - Continuity
Channel 2 - 12V - Middle leg of transistor - No Continuity

Seems i need to replace that transistor. I'll try at school tomorrow, if no luck i'll have to order it from a shop. Anyone know where i can buy one?

 

Yes, shorted transistor, and the first results confirm it's a PNP with the fan on the ground side. If you can't find the exact match, there's a Samsung KSB772 which is virtually identical, BD284 looks OK, or at a pinch try a BD140 but that will only handle 1A-worth of fans and that's pushing it. Same pin-outs.

 

I don't know what kind of fans you people use - and it's always good to be on the safe side, but I don't really see how 1A would be pushing it. There are 3 more channels working, so logically I don't see why anyone would run more than 1 amp worth of fans from a single channel.

But, if cpemma says so, there is a meaning to it

 

Thanks for the input guys So i'm looking for either a KTB772 or a KSB772. Anyone any idea where i can buy one of these in the UK? Anyone got one lying about?

 

The only meaning was that the original Nexus system was rated 15-18W (1.5A) per channel with the 3A medium-high gain KTB772 transistor. The easy-to-find BD140 is 1A max (12W), low-medium gain. There's also the question of what base resistor Vantec have used - on Leeum's photo there looks to be a phat 470R 0.5W connected to the base, which would pass 23mA, allowing about .23 x 40 = 0.92A (11W) max with a 40-gain transistor.

But as you say with 4 channels available there's not going to be many users wanting to push the limits.

 

Well basically, i have 2 case fans and 2 Titan 120MM fans for the radiator, i imagine the 120's will draw a little more current so i'll use them on channels 3 & 4
I just need to find one and hope i can solder it on