Soldering iron

[Jmsteele187]

Does anyone have experience with the Madell AT-201D, soldering station?  Last week my 936 station took a crap, and I'm looking for a replacement. 

[Brisance]

I have had a chinese 936 clone for a few years, no problems yet and coming from a cheap stationless iron, I can only say good words, for 40€ it has great value, maybe consider that?

[vigilante397]

The Madell AT-201D looks a lot like the Radioshack digital irons, which I'm guessing Radioshack just re-brands. If this is the case then I have heard that they are a great station for the money. I don't personally have experience with them (I use a Weller WESD51, which is a killer iron if you're willing to spend a little more), but I haven't heard anything bad about them.

[Jmsteele187]

I have had a chinese 936 clone for a few years, no problems yet and coming from a cheap stationless iron, I can only say good words, for 40€ it has great value, maybe consider that?

A 936 clone is what I'll be replacing.  I did like it, but it's no longer working.  If I could figure out what was wrong with it, I'd try to fix it.  All the guts are through hole components.

[Brisance]

Well maybe we can help, but first check if your heating element and sensor are ok, with a multimeter.

[Jmsteele187]

Being kinda new to this type of electronics, I'm not sure how to test either of those.  I'm not even sure which component is the sensor.

[Brisance]

Thats the part where you look for the schematic. Basically both of these elements should conduct, but not be shorted to eachother.

[Jmsteele187]

I'll try to take a look at it this weekend.

[PRR]

> it's no longer working.

Observations!

Does it gently hum? (Main transformer getting power)

Does the Heater LED come on? (Much of the small-stuff is getting power)

The most-stressed part (altho not very stressed) is the triac. The rest of the stuff drives the triac to a "short circuit" to get heat, and to "open" when heat is high. *If you are very confident in your live-chassis poking ability*, shove a plastic-handle screwdriver between T1 and T2 pins, which will pass current to the heater. Do not do this any longer than needed to feel heat! If the triac is left shorted the iron over-heats and burns-up. If you get heat that way, I'd replace the triac, it's only a buck. (However other failures are possible, and you should certainly look for bad solder joints (ironic!) and burnt/oozing parts first.)

Triac data:
http://pdf.datasheetcatalog.com/datasheet2/4/090h66a3qx9a7huioahpta6hx37y.pdf

Better plan with layout and parts list: EDITED
http://www.mmccs.com/mmarc/n0ss/hakko_936_schem-pcb_%26_mod_v1r7.pdf

[Jmsteele187]

> it's no longer working.

Observations!

Does it gently hum? (Main transformer getting power)

Does the Heater LED come on? (Much of the small-stuff is getting power)

The most-stressed part (altho not very stressed) is the triac. The rest of the stuff drives the triac to a "short circuit" to get heat, and to "open" when heat is high. *If you are very confident in your live-chassis poking ability*, shove a plastic-handle screwdriver between T1 and T2 pins, which will pass current to the heater. Do not do this any longer than needed to feel heat! If the triac is left shorted the iron over-heats and burns-up. If you get heat that way, I'd replace the triac, it's only a buck. (However other failures are possible, and you should certainly look for bad solder joints (ironic!) and burnt/oozing parts first.)

Triac data:
http://pdf.datasheetcatalog.com/datasheet2/4/090h66a3qx9a7huioahpta6hx37y.pdf

Better plan with layout and parts list:
http://pdf.datasheetcatalog.com/datasheet2/4/090h66a3qx9a7huioahpta6hx37y.pdf

I'll check to see if it hums like it normally did, before it quite working.  As for the LED, it will only come on for a split second when I flip the switch back and forth, then nothing.  I'll also check the triac like you suggest.  Also, I want to test the element with my dmm, but I'm not sure how.

[greaser_au]

Dave jones from EEVBlog reviews a chinese 936 clone:

www.youtube.com/watch?v=0GdV7XBae74

david

[PRR]

> I want to test the element with my dmm, but I'm not sure how.

Brisance >both of these elements should conduct

The element-- we see it is a 24V power. Assuming 48 Watts, that is 2 Amps. 24V/2A is 12 Ohms. That's the expected resistance when you poke the "heater pins" of the iron connector. The actual resistance will be different cold than hot, but something like that.

Actually there are only three likely possibilities. Infinite Ohms (no connection), a few dozen Ohms (happy), and zero Ohms (internal short, which probably blew something else). So exact computation is pointless.

The sensor-- I won't figure out which way it goes. But it is across a 1K resistor in a voltage-amp, so I would expect resistance to be over 1K at one extreme and under 1K at the other extreme. Which way is hot or cold or up, I dunno. But again, zero or infinite are surely wrong.

LED flash then out at least confirms the fuse aint dead. You sometimes get such an action if the fuse holder *or any other major connection* is loose, bad contact, can't carry a load. But there are other possibilities and that schematic is complex. I admit that I do not even see what they are doing with the power supply, after I get past C1. ZD2 looks backward to me; I dunno if that is a transcription error (twice) or something clever.

_________________________________________
I gave the wrong URL for "Better plan with layout", here's the one I meant:
http://www.mmccs.com/mmarc/n0ss/hakko_936_schem-pcb_%26_mod_v1r7.pdf