New Cheap Chinese Soldering Plates

[redwire]

I think it's not about being new- it's about not wrecking your LED project or the board you're repairing figuring it out as you go, kind or thing. Some people use scissor jacks to lift up the board, off the plate to cool it.

Originally Posted by clearchris

Link? Which one?

I ordered this one, who knows if it will come in with Christmas rush and shipping backlog. Notice- shipping has been jacked up a lot on all stores last week.
https://www.aliexpress.com/item/1005003391422040.html
This Aliexpress store has many possible sizes, voltages, temperatures.

[redwire]

My hotplate came in and it was only packed in a bag (no padding) so the wires got slashed. Sigh. It's the larger 12x7cm/4.72x2.75 inch one.
The standoffs have magnets in them which is nice, no label on the plate, the bag says 599235.02 400W led ptc BXBA-AX-BT but no voltage spec. anywhere.

The PTC heater is weird, I measure 220Ω cold but plugging it in 120VAC it started drawing over 5A which is 600W and kinda scared me, it blew my 2A fuse. No fuse, readings I got:
0 seconds, 0W, 220Ω, 25°C misleading PTC ohmmeter reading
10 seconds, 460W, 31.3Ω
30 seconds, 200W, 72.0Ω, 200°C
115 seconds, 108W, 133.3Ω, 225°C
125 seconds, 83W, 173.5Ω, 230°C

So it settles after about 2 minutes to around 230°C. I'll try some M-core LED's soldering/rework later.
I think the challenge is moving something hot off it, to a cool down area.

[stj]

dont use the magnets - when you heat a magnet the field drops

[redwire]

The magnets are at the far corners, on the feet. They don't get as hot. Not ferrite, it's some el-cheapo rare earth that are like candy over there. Many are good to >200°C so who knows.

The heater resistance went back down to 220Ω when it cooled down BUT this morning it was 42kΩ
If I push down on the plate it drops to a few hundred Ω, depending on where I push. So I thought it must be cracked... but plugged it in anyway. It's still working fine.
So the PTC is non-linear it acts like a MOV it needs higher voltage to fully conduct. Good to know, it's not a resistive thing I would have been fooled by the ohmmeter reading. PTC must be made of zinc oxide granules.
Either that or my plate is busted.