This device seems to be a clone of several other branded ones out there. The Atten / Aoyue 858 come to mind ;-) I bought it on ebay for 38€ delivered.
MAKE SURE TO ALWAYS UNPLUG THE MAINS CABLE BEFORE OPENING A DEVICE. CHECK REPEATEDLY, ESPECIALLY IF YOU HAVE TO LEAVE YOUR WORKPLACE. DON’T BECOME THE NEXT ‘DARWIN AWARD’ WINNER.
I think I’ve read some stories on the eevblog forum regarding bad mains wiring, so my first job will be to do a teardown and making sure that the safety-earth is wired correctly. See the images and my findings below.
At first glance, it looks pretty decent – considering the price! No loose wires or screws were encountered. The spade connectors used for the power input / safety-earth are self-locking. Nice. They’ve also added insulation sleeves. Nice.
Two of the mounting studs were cut off, so I wonder if the circuit board came from somewhere else.
There are plenty of HV isolation slots to be found. Nice.
Another indicator that the circuit board doesn’t quite match the front panel.
The circuit boards weren’t cleaned it seems. The opamp is an OP-70, used to handle the thermo-couple in the heater.
And now to the serious issues I’ve discovered so far:
Once the power switch is turned ON, one of the pins on the circular connector is potentially live! The CEE 7/7 mains connector is not necessarily used with a polarized outlet, so there is a 50/50 chance to have exposed mains voltage on the device. Not good. I’ve added a “! DANGER HV !” sticker right next to the connector. They should’ve used a different connector. Some of the other brands selling this device chose to have the wand permanently connected, avoiding the issue completely.
The inside of the wand looks acceptable, if it weren’t for the fact that some of those tiny wires carry 220V and about 3A (700W heater).
This my friends is a not-so-safe safety-earth wire. The connection is not something I’d bet my life on. I tried to solder the wire to the heater tube, which of course didn’t work. The tube doesn’t take the solder at all – and it gets too hot anyway, so it melts again, once the heater is turned on.
They should have used a spade connector for that wire!
In the end I had to redo this lousy way of hooking up a safety-earth wire. Not proud of it. I made sure there is some tension on the wire, so chances are higher the connection is not intermittent. But I guess I won’t be touching the metal parts while the thing is turned on (or hot). Maybe it is time for an insulation transformer. For some reason these things are prohibitively expensive for what they are: a box with a chunky transformer, some outlets and a resettable fuse.
Usability will be dealt with later. I have some victims to play with already.
All the images for your pleasure:
Here’s what Mr. EEVBLOG himself had to say about a very similar device some 2 years ago.
My next post will deal with using the device.