Weller Soldering Iron WES51

[bostonman]

I'll remeasure, and this time I'll connect one lead directly to the iron rather than the pin.

FYI, these measurements were taken without a tip in the iron and not plugged into the base.

[bostonman]

Just checked again using the iron metal shaft and all the pins measure the same, with obviously Earth ground to the iron shaft being 0 ohms.

[bostonman]

This has me a bit concerned for the quality of the irons.

My original iron (which was used) has lasted years, maybe about a decade, with several hours of usage, and who knows how long prior. The new iron (a Weller PES51) broke in maybe about 20min of total use, however, it's about six-months old leaving me without the option of returning it.

The used iron I bought to steal the PIC out of also has a bad iron.

[floobydust]

To me that looks like a ground-fault occuring in the heaters. It could be a quality or counterfeit problem in the heater/thermocouple cement.

Weller being bought out by Cooper Tool, Apex Tool Group evil Danaher, now Bain Capital investment firm means the quality has been through the wringer. Mexico seemed to be doing OK but the quest for maximum profit may have taken the brand to a new low?

[bostonman]

I agree about the ground-fault issue.

Since I don't have a working iron, I can only assume that the heater and thermocouple shouldn't have continuity between the two, correct?

I assume the heater should be the typical 11 ohms, the thermocouple should be very low (I would have expected even lower than 2.2 ohms), but the two should be isolated from each other.

All I can conclude: the thermocouple wire insulation has melted and one side is touching both the heater and metal shell of the iron. This would be why the heater has continuity to the metal shell. i.e. it's going through the thermocouple to the metal shell.

I'm going to purchase two more irons. If these two die, then I'm probably done with Weller at this point. Maybe I'll send an email to them regarding this iron, but no way can I purchase anymore should two more die on me; especially after only 20min of use. It's one thing if they last years and many hours of use, but if I get stuck with two dead irons in a short time, then maybe it's off to Pace.

I'm even very careful with the irons. If I don't plan to use them for a few minutes, I turn off the base rather than let the thing remain hot for no reason, when I set it down (or in the spring holder) I am gentle so I don't vibrate the heating element thus possibly cracking it, etc...

Before I would set the temp to minimum before turning on the station to avoid a high inrush of current, however, now that I'm more familiar with the circuit, it seems it doesn't matter if the knob is set to 100 degrees F or 1000 degrees F because the TRIAC turns on just as hard.

[bostonman]

I don't know whether I have good news or bad news.

The other day I sent an email to Apex telling them about the new soldering iron that worked for a total of twenty-minutes. Today they sent a reply stating they'll be sending a replacement, but they won't be available for several weeks (I think six).

Later I received the two new ones I ordered from Amazon. Before doing anything, I took resistance measurements on the pins: heater was 10.5ohms, thermistor 2.4ohms, side A thermistor to iron shaft (Earth ground) 2.2 ohms, side B thermistor to iron shaft (Earth ground) 1.2ohms.

From what I could tell, no resistance between heater and thermistor (as expected).

I plugged the iron into the base and sure enough, the base worked as expected along with the iron heating. At this point, I began experimenting with verifying the PIC. First I placed the K111 calibration thing onto the iron and did a factory reset (although it was unnecessary), set the knob to 600 degrees F, iron settled around there. I tried the temp lock feature which also worked. Next was the tip calibration, so I got the iron to 600 and did a calibration offset of about 50 degrees F. Sure enough, the temperature was off by 50 degrees F. The factory reset worked, and the tip offset was back to normal.

Next I wanted to check the tip temperature at various settings, from what I could tell, at 550 the tip was 560, 600 the tip was 600, 650 the tip was 645, 700 the tip............ died.

Yup, sure enough, the station turned off and the iron began cooling. Removed the iron, measured the pins, and the heater was 11.1 ohms and 1.1 ohms (each side of the heater) to the thermocouple.

I plugged the other new iron into the station, and the station worked fine.

Clearly the iron didn't overheat because I was measuring the temperature (and I never raised it above 700 degrees F). Having become familiar with the base circuitry, I can't think of anything that would kill the iron. If the TRIAC was bad, it would just be dumping 28VAC into the heater which is what normally goes into it.

The only thing I can think of is that the TRIAC isn't clocking correctly and the heater needs to have pulses in order to reduce inrush current.

I find it hard to believe Weller is making irons so cheap now that they last 20min, but anything is possible.

The conclusion is, with the exception of testing the 99min auto turn off (which I may try this weekend by plugging in a thermocouple into the base socket and tricking it into thinking it's heating an iron), it seems the PIC is solid. The factory reset works, it holds the iron at temperature well, the temp lock works, temp unlock works, and the LED blinks. Also, from what I witnessed, when the temp is locked, the red LED will stay solid until the temp is reached (regardless of what the knob is set to), and then blink; which matches the green LED state.

Anyone who wants/needs the PIC code, the one I extracted in message #114 is good, but the OSCCAL fix in message #118 is the one that allows you to program to a blank PIC and is what I ran the above tests to.

As for the iron breaking within 15 - 20min, even if the TRIAC was shorted (ignoring the fact the temperature wouldn't stabilize), the iron shouldn't break as a result. The only conclusion is the iron is junk which means I may have wasted all this time and money trying to keep Weller alive.

Edit: although the iron died when it reached 700 degrees F, that wasn't the first time it went that high. So I don't believe 700 degrees F is what killed it (although it could have stressed it); but it should be able to handle more than 700.

[Ian.M]

A temperature controlled Weller iron should be capable of running at 700 deg F all day, every day, for several years, so I doubt its anything you did.

Back in the day, Weller TCP series irons (with the Magnastat temperature control thermostat built into the iron itself, temperature set by the Curie point of a slug of alloy on the back of the bit), came with a PTAA7 bit as standard, which set the Magnastat to 700 deg F.  They were popular with repair shops and on production lines, and it was typical to run them all day, day after day. There were also options for 800 and even 900 deg F bits, but they tended to become severely oxidized if you didn't turn them off after use.  Later production replacement Magnastat thermoswitches had a poor reputation for reliability compared to the originals, and the bits seemed to have less durable plating.

Therefore, as even 25 years ago, Weller had spare parts quality problems,  it wouldn't surprise me at all that the situation has got worse!

[bostonman]

Interesting piece of history. It always amazes me how people have such knowledge regarding the history of a product and how much knowledge is on here.

I didn't think turning the temperature to 700 degrees F could damage it. In fact, usually I solder at 700 due to either myself or someone telling me to use that temp, and just continuing with it, however, I should maybe use a lower temperature like 650. When it comes to ground plans, I've had the iron up to 800 I believe.

In any case, assuming the base station broke the iron (just thinking out loud), the only methods I can think of would be: the transformer is damaged dumping higher voltage into the TRIAC therefore stressing the heater element or the TRIAC isn't pulsing and pumping constant current into the heater element.

If the transformer was damaged and dumping large voltage into the iron, I'd assume the temperature would have come up very quickly; not to mention probably blowing up the iron immediately. If the TRIAC wasn't pulsing, then the temperature wouldn't have settled.

If the TRIAC isn't getting the correct pulses, say it was getting pulsed too fast, could constant current/voltage cause the heating element to get damaged or can it stand a straight DC voltage (although it's really getting AC no matter what since the TRIAC is being fed AC voltage).

Most likely neither of the two above occurred leaving the only answer to be the irons are junk.

Someone on eBay had a non-working Weller priced very cheap which I purchased last week. I hacked my original somewhat bad enough that I'd either spend a few bucks on replacement components, or just swap the whole board. This iron actually seemed to work (I connected a thermistor to the connector and it turned on), so for a few bucks, it was worth getting a non-hacked board (most of my hacking was due to using a junk iron along with wires breaking from moving the board around).

What I'll probably do is use my old junk iron to swap boards (put this board into my original) and then use the second new iron I just bought on that station. If this new iron breaks, it will have happened on another station thus pointing fingers to the irons themselves.

[bostonman]

As mentioned, instead of repairing all the hacks to the board in my original station (that I've owned for many years), I just swapped boards with the one I got cheap off eBay. Turns out the station from eBay wasn't broken and works just fine (the owner must have had a broken iron and thought the station was bad - or thought not having an LED without an iron plugged in meant it was bad), but it had worn numbers on the face which is why I swapped boards into my good unit.

After using the K111 to measure the tip temperature, my opinion is to not bother with calibration offset unless it's for a specific temperature and accuracy is needed. I'm seeing offsets of 10 degrees F (although maybe I need to let things settle for much longer). Setting the dial to 600 degrees F seems to be the sweet spot where the iron temp is almost exact, then the temperature isn't as accurate the further away from 600.

Currently I have two working base stations, my original one with the new (used) board which means it has the original PIC, and the second one I bought to steal the PIC from to upload it here. This second one is all original except it has a new programmed PIC from in message #118 because I had to cut the legs from the original (i.e. sacrifice it) to upload the code for everyone to have.

Thanks to the OSCCAL file in message #118 and the station having just about all the components that can easily be replaced, I think it's safe to say anyone reading this thread can repair their station; and now know how to set the LED to blink or remain constant.

The big issue is the cheap soldering irons. I've bought three (one several months ago but only used it a total of about 20min) and two out of three failed; and I'm holding my breath on this third one.

The company is supposedly sending a replacement for the first one, and I plan to return the broken one I just bought to Amazon, but maybe the quality is so bad that the irons are just junk and dumping Weller is the best option. It won't make sense to continue buying irons in the future if they keep breaking after only 20min.

Yesterday I used my original base station to power the new iron (which was 2of2 I just bought of Amazon) and it seemed to work just fine for about a full ten to fifteen minutes. Wondering if maybe the other base station can be damaging the irons, I tried that station again and the iron remained working.

I previously asked and wondering, does a possibility exist that the station is damaging the iron? I can only think of two situations where the station could do this: the transformer would have be putting out greater than 28V AC (I doubt this could happen and the iron would be heating at a rapid pace), or the TRIAC is sending a constant current into the heater (again though, I don't see this as a possibility since I'm assuming the heating element can just take straight DC without getting damaged - assuming the temp is monitored and the voltage removed to avoid burning out the heating element).

I plan to burn a few PICs to have as spares, but I need to buy more blank ones. Due to questioning the quality of the irons, I may hold off rather than wasting my money. If these irons continue breaking, then I don't see a reason to waste time with Weller stuff.

[bostonman]

Tonight I dismantled a broken old iron. On a new iron, I measured (all in ohms):

Across the heater: 10.5
Across the thermistor: 2.4
Heater A and B side to thermistor: open
Heater to Earth: open
Thermistor side A to Earth: 2
Thermistor side B to Earth: 1

On a bad iron, I measure (all in ohms), note that side A and B may have mistakenly been interchanged at some point:

Across the heater: 10.5 (same as new iron)
Across the thermistor: 2.4 (same as new iron)
Heater side A to thermistor side A: 13 (different)
Heater side B to thermistor side A: 2.4 (different)
Heater side A to thermistor side B: 12.2 (different)
Heater side B to thermistor side B: 1.6 (different)
Heater side A to Earth: 11.5 (different)
Heater side A to Earth: 1 (different)
Thermistor side A to Earth: 2 (same as new iron)
Thermistor side B to Earth: 1 (same as new iron)

When I dismantled the broken unit tonight, starting with the easiest thing to explain, the inside tube which is metal had Earth ground (bare metal wire) going down the side of the inner part, what looked like epoxy, and the two thermistor leads down the center. This seems like the thermistor should be isolated from Earth ground, but isn't due to my measurements above; and I'm baffled by this.

Now the more confusing part is the outer part of the tube has the heater wire wrapped around what seems like a section of non-conductive material sprayed onto the metal tube. Keeping in mind I had to apply some force to remove this and probably some things got jolted, I can't figure out a few things.

The heater wire is bare (or maybe all burned off). If the wire wraps around the shaft on the non-conductive part, how is it not shorting on the windings and reducing the resistance? I tried winding the wire so the windings didn't short together and for the life of me couldn't use up all the wire without turns touching.

Also, one manufacturing mistake and it seems like the wire can touch the metal shaft shorting the heater to Earth ground.

I expected the heating element to be some sort of resistor and never expected it to be a straight piece of wire (unwound it measures 11ohms).

In any case, from what I can tell, the insulation on the heating wire (i.e. element) is burning off and touching the metal Earth ground, but things are so tight in there that I can't figure out how the iron is made with enough room for error during manufacturing. The other possibility is that the inner tube is getting misaligned at some point and touching causing the heating wire to touch the case.

[floobydust]

If you consider the station's schematic, you can see 24VAC power has one common leg earth-grounded, and the triac and the thermocouple as well.
If the thermocouple shorts to the heater, this would normally cause a meltdown due to the heater always being energized, so Weller has the PTC fuse on thermocouple (-) to prevent this from happening. But the TC amplifier would see wild AC voltage. This is my take on the connector:

Pin 1 - N/C
Pin 2 - Heater red J1, 24VAC power
Pin 3 - Thermocouple(+) orange
Pin 4 - Thermocouple(-) yellow
Pin 5 - Earth-ground, tip
Pin 6 - Heater red, triac

WES51 manual:
"1.1   Check heater resistance from pin 2 to pin 6 of the connector, should measure 9-11 ohms."
"1.2   Check sensor resistance from pin 3 to pin 4 of the tool connector, should measure 1-2 ohms."
"1.2.3 Check resistance from pin 3 to pins 2 and 6 of the tool connector, should measure 1 megohm minimum." {I think typo- should be to GND pin 5}

[bostonman]

Am I missing something? Earth ground is only on the primary side of the transformer which is what the soldering iron tip is connected to (once the iron is plugged into the station).

If the iron isn't plugged in, then the tip shouldn't be connected to anything. Once plugged into the station, then one side of the heater should be common to ground through the resistance of the secondary of the transformer and one side of the thermistor should be common to ground.

[floobydust]

Sorry I must be wrong about the 24VAC secondary being earth-grounded, there's not a decent schematic for the station to be found.
In this pic I see the line cord green connecting to the transformer core and to the wand connector, but there's another green wire going somewhere, it's not the PC board though. It might be a double-ground to the transformer core. So the secondary must be floating.
https://www.eevblog.com/forum/reviews/is-the-weller-wes51-(120v-60hz-60w)-safe-to-use/msg2232633/#msg2232633

[bostonman]

It's okay, you just had me second guessing myself.

The green wire from the AC plug screws directly to one screw of the transformer (which is screwed into the plastic case). A short green wire is also on the same screw and the other end is screwed down on another corner of the transformer. The green wire from the iron socket has its own lug and screws onto either one of the transformer screws.

I'm not a fan of how this is done because the wires become loose due to the plastic not being a solid screw mount. if things work out with these irons, I may solder the soldering iron Earth ground directly to the AC line green wire while keeping it all screwed on the transformer.

This way the soldering iron can't have a loose Earth ground connection. I'm uncertain if screwing Earth ground to the transformer does anything such as removing any build up of voltage or if it's a place holder for the wires.

In any case, the thermistors being connected to the soldering iron case (i.e. Earth ground) on a good iron even with the iron not plugged in is a bit baffling.

[Ian.M]

Yes, that's sh!tty grounding, and Weller knew it as evidenced by the short green bodge-wire to the other transformer screw.  The transformer core grounding slightly increases safety, as if the primary burns up, it may short to the core, and grounding the core improves the chances of tripping a breaker before total melt-down!

I'd suggest adding a short two hole plate cut from brass strip, so you can through bolt the three separate ground wire ring terminals together securely, with a star washer and lock nuts or a nyloc nut.

It may well be that the thermocouple is formed by spot-welding two thermocouple wires together to the back wall of the well in the end of the heater core that holds the bit.  It would certainly be cheaper and more robust than fitting an insulated thermocouple in a  well in the back wall.  That's only viable if the whole thermocouple circuit is only grounded at that point.

[bostonman]

I'd suggest adding a short two hole plate cut from brass strip, so you can through bolt the three separate ground wire ring terminals together securely, with a star washer and lock nuts or a nyloc nut.

I'm not exactly sure what you mean, however, I was stuck on the notion that the screws need to be tight in the plastic. I can technically cut off one standoff to gain room for a nut underneath and use a screw through the transformer to Earth ground it; and then solder the soldering iron Earth ground wire to the AC plug Earth ground.

Apex is sending a replacement iron for the one I bought months ago and failed after a total of about twenty-minutes use. I just replied to their email informing them about the new iron that also broke within twenty-minutes (one of two I bought off Amazon) and that I'd be returning it to Amazon. Also, I offered to work with their engineering team on the measurements I took in hopes they want to improve their quality.

I don't do daily soldering, so testing these irons for long periods will take place over time leaving me with the possibility the heater will once again short leaving me not only stranded, but them being out of warranty.

On a side note, I had one blank PIC left that I programmed yesterday to have as a spare. I noticed that the box labeled 'buffer clear on data load with FF' was checked. Seeing it checked implies that's the state it was in during a previous program, and believe this should have been unchecked. Just to confirm, I unchecked it, closed the program, reloaded, and it was still unchecked; so the default doesn't seem to be having it checked.

If I indeed accidentally left this checked during a previous program, would that do anything to the PIC? Since the PIC seems to work just fine, I'm sure it was either unchecked or doesn't matter, but thought to ask.

[Ian.M]

My suggestion is to put one end of the new plate under the head of one of the transformer core mounting screws, leaving the hole in the other end sticking out to through bolt the grounds to.  It avoids giving up one of the mounts to through-bolt through the core.

[floobydust]

There's three elements to the wand - heater, thermocouple, shell. The thermocouple is isolated from the heater but we don't know if the thermocouple is spot welded to the shell, there's no mention in the Weller manual.
That would mean the secondary-side ends up getting earth-grounded by the thermocouple, no biggie it doesn't really matter much.

But the reason I'm mentioning it is connecting an oscilloscope or PIC programmer+PC when there is a short from heater-TC would cause a ground-fault through the scope's earth-ground if the (defective) wand was plugged in. It depends where the scope GND was connected. You might have gotten some oddball waveforms.

Weller has always had trouble with their electrical safety - having a primary fuse they flip-flop around that, some stations have it some don't, and the double-ground on the power transformer core is another silly example of somebody wrongly interpreting a safety standard. I've seen it happen with amateur certification agencies, they'll insist on something stupid like that in order to meet a clause in a safety standard "double bonded", despite it actually being wrong. It's in a plastic case with no locknuts, and a melted transformer bobbin would short primary to secondary and here we have no coverage for that.

[bostonman]

Ironically, at some point today I thought to myself that maybe the thermocouple is welded to the shell. If this is the case, maybe it's done for better thermal transfer so the iron maintains temperature better.

Either the manual or another write up (I found a write up on dismantling the iron, and believe another one on something else) mentioned something about removing Earth ground can affect temperature stability. So maybe a correlation exists between the two, but it's obvious the thermocouple is low resistance to Earth ground.

As previously mentioned, first of all, the heater wire needs to be perfectly wound around the non-conductive section of the tube. If the windings touch each other, then resistance is lowered, and, If the windings touch metal, the heater shorts to Earth ground.

I'm uncertain about grounding codes and what is right/wrong. Personally I wouldn't get involved with designing grounds for safety unless I knew what I was doing rather than risk injuring someone.

From my limited experience, usually transformer plates are coated. Seeing Earth ground screwed into the transformer had me wondering if this actually does anything. Prior to reading the feedback in this thread on the setup, my guess would have been a transformer would short and blow the input fuse (or breaker for the outlet).

At some point I should research grounding methods, practices, codes. A few years ago I designed a basic power supply and the transformer was encapsulated in plastic without an Earth ground terminal. Not sure why this would be safe should a short occur versus the one in the Weller (unless the open concept is considered more of a fire risk than one encapsulated in plastic).

On a side note, my email to Apex was forwarded to a Product Support specialist. I'm sure they'll tell me these iron issues are not common and apologize.

[bostonman]

I took a few minutes to piece together what I think are all the LED status indicators and settings for the WES51 station (see attached).

Although some are in the manual, I figured having one complete document may benefit others; especially since things like setting the blinking LED isn't in the manual.

Apex hasn't got back to me about the first bad iron (I even sent a follow up email), and I returned the other to Amazon requesting an exchange.

Eventually I should have three good irons, but doubt I'll be using them for any extensive amount of time to test them fully. If they are pieces of junk and will also break in approximately 20min total use, then I sense I'll eventually have three broken irons all out of warranty.

Can I test the new iron(s) by leaving it powered at 600-700 degrees F for 20-30min without damaging anything? I'll use a tip I don't really care about and apply some solder, but I don't know if it's practical to just leave in the holder without exercising it by soldering.

[Ian.M]

Thoroughly tin the bit, let cool and wrap tightly in aluminum foil to exclude as much oxygen as possible, and I would expect you can run each iron for many hours as a soak test, without damage other than due to pre-existing defects.  24H, eight hours a day  over three days wouldn't be unreasonable, checking, re-tinning and re-wrapping the bit each day, as that's fairly typical of commercial use in a busy workshop.  If they can't stand up to that, best to find out now.