Sketchy Chinese Ovens
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Sketchy Chinese Ovens

by spiffed on Thu Feb 04, 2010 6:44 pm

I can't stress this enough, don't buy a small Chinese made reflow oven, it just isn't safe. More than one person in this thread share my sentiments.

Our story
In the course of business we reflow about 10 boards/day (obviously not just 10 every day, but say 100 once every two-weeks). Originally, we used a plain-jane toaster oven, a digital thermometer, a stop-watch, and a careful eye. This actually worked pretty well, assuming someone was willing to devote their attention to watching the thermometer, and we kept the panel size below say 6"x4". We did this since 2006.

In November, we had need to do single boards about 8"x8" with many power-transistors, something beyond the capacity of our lowly toaster oven. We purchased (from eBay) a "Small Factory" brand 1500W IR oven with a convection fan. It cost us $360 + $100 S&H. It had dials to set the soak temp and time, and a nice bell that told you when your boards were done. While it didn't do a perfect job (the corners of large boards had some discouloration) it did what we bought it to do. We put boards in, it whirred, it went ding, we took boards out.

Today (Feb 4th, 2010), it did something else: It caught fire!.

I was sitting at the "assembly desk" (where the machine rests) placing new boards while a set of smaller boards ran through the machine. Realizing it was taking longer than normal, I looked up to see grey smoke seeping from the corners of the machine. I opened the door to check the problem (letting in fresh oxygen) and the machine's elements burst into flames. Thankfully by this point the smoke alarm had been activated and my intern jumped in with the fire extinguisher.

The root cause would appear to have been a shorted thermocouple causing the oven to run at full output, without even the timer activating. The thermocouple is routed to the back of the enclosure where it can be fastened to the board surface, it does so by escaping from a small hole behind the fan mounting, where (as a cost savings measure I assume), it runs through a raw hole punched through the sheet metal (but behind the insulation). Over time (two months!!), the metal had cut through the cable jacket and wires. After the oven was cool enough to examine, we found the "probe" end of the thermocouple came out with a small yank and the wires leading back to the controller stripped bare and pinned against the metal surface.

Unfortunately I don't have pictures of the oven, before or after it's excitement, but I do have a picture of the oven tray with what's left of the PCBs. (attached)

The predictable end to the story, is both the manufacturer, and the eBay seller are long gone. Hopefully, this will make someone think twice before trying a cheap Chinese reflow oven. Personally we'll be going back to the toaster oven, but maybe we'll add a PID to it now.
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Re: Sketchy Chinese Ovens

by adafruit on Thu Feb 04, 2010 7:03 pm

thanks for posting this up, spiffed. there seems to be a lack of good <$1000 reflows. the goldflows look fantastic, and we had one at the lab in school it was quite a nice machine but they're $4000+

was it a T962? viewtopic.php?f=42&t=13449

all i hear are horror stories about these '$300' ebay ovens. yow! my nose hurts just looking at that epoxy mess :(
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Re: Sketchy Chinese Ovens

by spiffed on Thu Feb 04, 2010 7:29 pm

No, we purposely bought one that wasn't a T962 after hearing horror stories. I haven't seen one like ours for sale since.
  • It had a door and slide-in trays instead of a drawer.
  • It had dials instead of the LCD+buttons.

If it's still in the trash tomorrow, I'll get a picture of it (covered in foam).
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Re: Sketchy Chinese Ovens

by adafruit on Thu Feb 04, 2010 9:56 pm

a photo would be appreciated, even on fire :mrgreen:
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Re: Sketchy Chinese Ovens

by spiffed on Mon Feb 08, 2010 2:52 pm

Sadly, the garbage man (or the metal reclaimer) had grabbed it by the time I was in yesterday.
Our little toaster oven is cooking along just fine though.
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Re: Sketchy Chinese Ovens

by ktownsend on Tue Feb 09, 2010 12:52 pm

I think I fired my Chinese oven up twice and when smoke started pouring out of it I stuck it out front with the trash. Total (and scary) waste of money. I've been having a great time with this, though: http://www.reflow-kit.com/rkuk/order_pr ... 634dad52ac It's overpriced for what's inside it, but it works well (once you raise the reflow temp to around 250°C), and gives decent results with lead free paste. 220V only, though.

Kevin.
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Re: Sketchy Chinese Ovens

by adafruit on Tue Feb 09, 2010 2:26 pm

cute! what oven did you have?
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Re: Sketchy Chinese Ovens

by Agent24 on Sun Mar 06, 2011 7:54 pm

Why not buy one but just fix it, do what should have been done in the first place and install a grommet or something to cover the sharp edges?
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Re: Sketchy Chinese Ovens

by Philly on Mon Mar 07, 2011 10:00 am

The T962 is great, Im ordering another at the moment. Smoke usually comes out the first 4-5 times you use it(thin white smoke, probably burning grease etc) then it seems to work fine. The first has processed around 800 Xbox 360s and 5-600 PS3s, along with 100+ DS and about 18 PSPs. Then theres the boards we do, about 50-60 a week.

All good so far, Im ordering the smaller T962 this time, dont need another massive machine :)
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Re: Sketchy Chinese Ovens

by gsattler on Mon Mar 14, 2011 4:20 pm

the T962 is okay if you are doing small boards and only use the very center of the oven. Beware of fires though, that thing is seriously poorly made.

Anybody in the market for a pretty good reflow oven, check out the APS GoldFlow GF-B on eBay now for $3200. Its been listed for 20 days or so and I bet they'd take a lower offer at this point. I have no interest in the sale, but my solder stencil manufacturer says its a nice oven.
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