STC-1000 went bang

[Pataka]

Are all STC-1000s created equal?

I ordered one from Ali Express, which took an absolute age to arrive here. Finally it arrives, so I go and buy the parts I need, wire it up, and get an abysmal failure.

At first, I thought all was going well, because the LEDs lit up, then they went to EE and it began one long beep. I decided this must be because the temperature probe wasn't connected. So I unplugged it at the wall, wired the probe in, powered it back up... LEDs lit up again briefly, followed by a shotgun bang, then smoke.

I can't be totally sure because there's not much left of it now, but I think the culprit was a small ceramic resistor at the far side of the PCB, immediately in front of the main power input.

Our voltage here is 220v, and my unit was rated for 110-220v.

*edit* A meter test at the moment shows our voltage is 240v. I wonder if that was just a bit too much for the poor thing.

Any thoughts?

 

[Tytonegro]

Was it a resistor or a capacitor that blew up? I would expect these devices to have a capacitor as main part in the power supply. That might blow up when it works to close to its max. rating. Either way, it probably can be repaired for 1 or 2 $.

 

[Pataka]

Was it a resistor or a capacitor that blew up? I would expect these devices to have a capacitor as main part in the power supply. That might blow up when it works to close to its max. rating. Either way, it probably can be repaired for 1 or 2 $.

It's not a capacitor. Wrong shape. I'm pretty sure it's a resistor. The only thing with replacing it is, I have no idea what rating it needs to be. There's literally nothing left of it apart from the wires now.

 

[Pkrd]

Some have stickers that say 110V, some 110 - 220, and some 220. Hopefully whats inside relates to the sticker but who knows from aliexpress.

40$ from brewshop at the moment, bit cheaper from trademe.

 

[Pataka]

$30 will one from TradeMe at the moment. Maybe it's just my optimism, but it does feel like I probably received a unit that doesn't like our voltage here, regardless of what the label says. I've seen students in secondary schools flick the voltage switch on PC power supplies from 220v down to 110v and it usually ends the same way as my experience did. The only thing putting me off is that it did run for several seconds the first time I had it wired up. 220v in a 110v unit usually ends pretty quick.

I guess I'm wanting to be as sure as I can be that it wasn't a wiring screw up on my part. I would have thought if that was the case, I'd be dealing with a tripped breaker at the mains before it had a chance to damage the STC, or no power at all to it. The input terminals are the hardest ones to get wrong on the STC, and as I say, it started fine. Other than supplying phase into the temperature controller pins, it's hard to think of a way to destroy one. If that was what happened, I suspect I'd be seeing damage in another part of the unit, and not so close to the power source.

 

[beerlover77]

Does the part that malfunctioned have color bars?


*edit* I just re-read your post that the thing is un-identifiable.

 

[kh54s10]

If the thing was rated for 110V and you put 240v through it --- NO WONDER!!! It is fortunate you did not start a fire...

 

[raouliii]

.... The only thing putting me off is that it did run for several seconds the first time I had it wired up. 220v in a 110v unit usually ends pretty quick......

It could have taken a few seconds for the component to heat up from the overcurrent. If the unit was labeled for 220AC then you likely didn't damage it with the input power.

I would guess the voltage is transformed down to 6 to 12 vac, rectified and voltage regulated before being applied to the rest of the board.

.......I guess I'm wanting to be as sure as I can be that it wasn't a wiring screw up on my part........

A wiring problem is THE most common problem with these controllers. Pictures are worth a thousand words.

 

[Tytonegro]

It could have been the inrush current. If something was wired up faulty (short circuit?) the resistor might have blewn, but also when the thing works close to its limits.
Below a link to info about capacitive powersupplies. The resistor at the entrance 100 ohm / 1 Watt is the one I expect to have blown. (2nd schematic on page)
You can try to track down the board and see wich one it is.
Good luck!

http://www.electroschematics.com/5678/capacitor-power-supply/

 

[cannman]

Post the wiring diagram you used...

 

[IslandLizard]

Sorry to hear about your STC's early demise. A few years ago I bought a couple of them for around $20 each at Amazon, they worked fine on 120V. Sadly, they are the non-re-programmable type. The "Inkbird ITC-1000" seems to have improved features, based on a similar design.

Yup, pictures of the wiring that caused the bang and a closeup of the inside can tell us a lot more. Some of those STC-1000 units were for 12V DC!

I have the feeling the rectifier diode(s) and/or voltage regulator blew up. The diodes are small black cylindrical parts with a silver or white ring printed on one end. Resistors don't go out with a bang typically, they just silently overheat and the film burns up.

 

[Pataka]

You can find more discussion (and pics) over here

http://aussiehomebrewer.com/topic/91186-stc-1000-went-bang/#entry1377317

While I'm enjoying the investigation now I've written the thing off, my solution to this problem has been to order an Inkbird controller that's pre-wired. I'd rather have something that just works.

 

[doug293cz]

You can find more discussion (and pics) over here

http://aussiehomebrewer.com/topic/91186-stc-1000-went-bang/#entry1377317

While I'm enjoying the investigation now I've written the thing off, my solution to this problem has been to order an Inkbird controller that's pre-wired. I'd rather have something that just works.

It would help if the pictures weren't on a site that requires a userid to see them. I'm not going to set up an account just to look at a few pics.

Brew on

 

[Pkrd]

I never knew that inkbird had kiwi plugs. Good solution. The extra bits for the STC really add up $$.