Weller station repair EC2100

[Trakehner1]

Hello,

New here but have been reading this website for a long time Thanks to Dave`s reviews, I now use a Fluke 179 and am very very happy with it.

My soldering station recently ceased to operate. The model is a Weller EC2100A-ESP and is in use with the EC1201A iron. It won`t heat the iron.

The station works fine, temp display and etc. is fine, the output gives 12.36V on the upper right pin, 3.5V on the pin underneath but between the two I measure 23.96V. How come ( first question )?

The two wires that go to the heating element are white and yellow. Between these pins on the station I get 23.96V as noted above. But when I measure on the iron pins for the same cables - there is no voltage. If I reference to ground I get the same readout on both - around 11.9V. But the station outputs 3.5V on the pin that measures 11.9V at the handle. The heater itself gives a reading of 12ohms so I suspect it is good, the temp sensor also seems good.

My own conclusion is this is a cable problem and one the cables have broken somewhere in the line, maybe either close to the handle or the station plug. But when I check for continuity, they seem fine and not intermixed. Really confused on what could be the problem.

The station has a switch which has "set" and "read" modes, when I put it to "read" it shows about 700C. I have no idea what the read mode is for, suspect it should show the tip temp and switch power being fed to it for safety so you can cool down the station safely ( only guessing hear ).

Would appreciate any input on this matter, thanks a lot!

[Smith]

The read mode shows the actual temperature read back by the unit. Basically the unit doesn't seem to heat up because it already thinks its at 700 degrees already. Of course 700C is too high. I would suspect the wiring over the station itself. A bad wire connection would be my first guess, I have seem this multiple times. If you can find the spot in the wiring which is faulty (which normally is about an inch from the connector, or the heater, you can feel it in the cable) you can just cut away the bad part, and reconnect the shortened cable.

[Trakehner1]

Ok, so the read mode changes the game. I did try it a few minutes ago with no cable connected and it still produces an abnormal temperature of over 600C so whatever it is, it is within the station. I remember it had a transformer and a single board with the display attached to it, must be something on the board.

[Smith]

I would recon it would read a high temp when there is nothing connected. If this wouldn't be the case, a cable failure in the readback would surely fry the heater element.  Just look for a layout of your iron on the internet, and check the temp readback.

[Trakehner1]

Did some more extensive tests today. The sensor gives 22ohms on the pins, the heater something like 12 ohms or so. All cable have perfect connection to the station and from the station plug to the circuit board. I guess the iron and cable are fine so problem must be within the circuit board.

What I noticed today - when I switch it on and is set to read mode, it would go up to about 700C then start dropping to under 80C ( I switched it off at 80C but I guess it would go down to zero ). I replaced one capacitor with the same value but new ( Panasonic AM ) and no change ( the big blue leaded cap ). I get 1.6V on the tip, this shouldn`t be normal, I think?

I searched online but could not find any schematic for this unit, neither anything that looked similar. Can someone help what model is closest or what parts could be causing the problem? The resistors on the board seem fine, the caps measure within the specified uF spec ( still could have a bad one ). The two transistors seem good, so I guess it must be one of the chips?

[Smith]

I repaired some Wellers, but I never had a ceramic board. Seems like they used them in some other series too. I have an EC2002 which is build with simple off the shelf parts on regular PCB, but I have seen people with ceramic PCB's too. It would be best to just test all components. If you cant find anything, you might contact Weller for a replacement PCB.

[Trakehner1]

Hi Smith,

Thanks for offering help. Yes, this one is with a ceramic board.

I did measure the elements today, one ceramic capacitor measures 0.9ohms and no capacitance at all. Moreover, it is on the temp return path, so I believe it is the faulty component. I have encircled it with red. Problem is how to find out its value, letters are unreadable...

I will recap all electrolytics with higher rating ones, have opened it already and they`d eventually fail so why not do it now

[nanofrog]

I'm seeing some sort of marking on the circled part. Do you have sufficient magnification & light to try and read it?

[Smith]

just desolder the thing, and measure it again to be sure it's the broken part. I think you should be fine replacing it with a standard 100nF or leaving it out for testing. Maybe it will give some swing on the temp reading, but it should be fine. I would recommend to place one if it all works.  Maybe someone on the forum can measure his capacitor.

[Trakehner1]

I desoldered the cap and it measures 11nF. I cut the cable and measured the voltage across the heater power wires - got 24.86V without the cap in place. But here starts to get weird - once I soldered these to the heater pins, voltage would disappear. I disconnected the thermocouple and still no voltage. Is it possible to be a dead thermocouple that is left opened?

The increasing temp issue changed, now read remains at around 70C but still this is not correct. If the station reads 70C it should feed the iron to boost temp but this isn`t happening. These seem rare and it has so far been impossible to get a manual or at least a troubleshooting guide.

At least I hope this topic to be of use to others in the future as not much info is available on this model.

[Smith]

Could you heat up the iron (with a second soldering iron or something) and see if the readback temperature changes? 70C would be high, but I have never seen a really accurate Weller of this type. Of course the short could have created an over current in the thermocouple element.

[Trakehner1]

Heat it up with another iron - that was a good idea, thanks. Did it, no reaction on the display.

[Smith]

You could also measure the sensor of the iron while heating it up with anorther soldering iron.  Just measure the resistance between red and black if https://softsolder.com/2011/12/14/weller-ec1201a-soldering-handle-failure/  is correct. I'm not sure about the value, but i guess it should increase quite linear.

EDIT: just read somewhere it should read about 22 ohms at 23 degrees C

[Trakehner1]

I think I mentioned it already but I took another set of measurements today.

Cold iron:
- sensor pins: 22.3ohms
- heater pins: 11.9ohms

Warming up iron ( warmed with another 30W iron ) after about 2 minutes:
- sensor pins: 28.2ohms - slowly increasing in a linear fashion by 0.1ohms/1.5 seconds
- heater pins: 12.2ohms

Hot 30W iron:
- sensor pins: 34ohms
- heater pins: 12.3ohms

The Weller tip was hot but I could touch it for a second or so ( when at 34ohms ). Station showed no indication of changing temp on the read setting. To me, the iron is fine, problem is somewhere in the station. yesterday checked the transformer - fine, so its the PCB only that is left. It has a triac, two control chips, one branded Weller, some ceramic caps, two shotky diodes and six electrolytic caps. To me the most obvious component to check would be the electrolytic caps, this unit is 23 years old and they`re usually the first to go. I already ordered Wurth 2000h @ 105C ( original ones are 1000h @ 85C ) and a few ceramics to replace the one that gave weird readings, will first replace these. If problem persists, then it should be one of the chips. If its the Weller chip, that would be a bad surprise.

[Bud]

I have a Weller which after 15 years developed similar symptoms, i.e. Temperature drop in both the handpiece and display. I bought a replacement heater assembly and reused the existing thermal sensor, i also cut the power cable an inch behind the handle and resoldered to the heater socket. This fixed the problem. I do not really know if it was the heater or cable, i did not care and did not have time to dig deeper, i just wanted the iron back.

[Trakehner1]

While browsing for more info and getting ready to test the triac for gate current, I stumbled across this thread concerning the very similar EC2002M with ceramic board. See post 15. Will try what he said.

http://www.electronicspoint.com/threads/weller-ec2002-erratic-temp-display-on-set-mode.233710/

[Trakehner1]

Ok, an update.

I bought new caps but for the sake of the test - assembled the station without the new caps, just cleaned the board. The tracks were all covered by wide black compound, probably some copper or tin oxide and this substance appeared to be well over a few nearby tracks. The station worked like a charm after a clean up, seems the ceramic ones may develop such issue over time.

I then replaced the cap with the new Wurth ones ( nothing changed, still worked as in the initial try ). Then, assembled the station, mounted the board and it doesn`t work again...Initially it would show 666 for a fraction of the second and then it would switch off the display and the iron won`t heat. Then, after some time it would start producing nonsense readings that would change by 30-40 grad per blink. When this blinks and I connect the iron, it would switch off the display again. I double checked the iron, all fine, but it presents a load so I guess something is overloaded. I did change nothing and it just stopped working after it was assembled. Will track this symptom today.

[Trakehner1]

Today it all came to an end. The issue was micro cracks on some of the tracks. I did repair them and while soldering the main ribbon cable, I cracked the board. I think this is beyond repair due to the multi layers.

Is there a way to acquire a new board, but not a ceramic one? The model does not even appear online, but the board looks the same as the EC239.

I have to admit I am pretty disappointed by the quality of the board and the components, not sure why we pay such ridiculous money for a transformer in a case with a £3 PCB which appears well backed with engineering flaws. Weller support on this issue has been non-existent, not even offering to sell me a board ( they did not reply at all ).

[Trakehner1]

I cannot find a part to replace the ceramic board and this weekend started to copy it to Sprint Layout. I plan to design a new PCB, have already desoldered most of the components from the original ceramic one. It had more cracks which became evident under light.

The question is - on some spots of the ceramic board, there is a black plastic film which connects separate tracks. What is it, to me it seems like high resistance but why not just put a resistor? I think these are visible on the board pics above.

Would appreciate some input.

[Andy Watson]

I see some blue film - which is used as a layer of insulation to allow additional conductive tracks to be laid over existing tracks. The only black parts that I see on the ceramic are resistors that are etched-in or deposited as part of the fabrication process.

[PA0PBZ]

The question is - on some spots of the ceramic board, there is a black plastic film which connects separate tracks. What is it, to me it seems like high resistance but why not just put a resistor?

Yes, these are resistors. The main reason to do it this way is they can be laser trimmed, as you can clearly see on the one just above the Weller DIP. Then when your process needs resistors like this it makes sense to use the same process for the other resistors.

[Trakehner1]

An update. I did get pretty frustrated by the design flaw of these ceramic boards - mine had about 3 cracks in it, easily visible, some of the film resistors had multiple discontinuations too.

The replacement board is hard to find, what a shame for an otherwise good tool. So, I decided to go the long way and did my own version of the original PCB - made of standard material and with 70 micron foil ( thickest I can get to here ). I did modify some parts of it to be able to accommodate higher rated parts and use through hole capacitors instead of the annoying SMD ones. I will replace the film resistors with SMD/throuhg hole ones too and will add extra cooling to the triac and Weller branded chips.

Wasn`t easy as the blue coating mentioned already is actually ceramics and is impossible to remove with steel tools, perhaps a diamond coated blade would do it easily. The coating separates the tracks and creates a dual layer board on one side only. I had to trace the tracks one by one on light or with a multimeter but, here is the final board ( same size as original ).

I had to order a total of six as the board is smaller than the minimum size, will test it very soon, if it works - the remaining ones are available. For non-European countries, might be easy to send you the Gerber/Excelon files and produce your own

[Trakehner1]

Ok, I got the new boards, transferred all the components and after I plugged it, same issue as before - random erratic temp numbers on the display. So, it appeared the problem was elsewhere.

I moved on to the display board and noticed that when I desolder one of the 1uF caps, the erratic behavior stops. Moreover, I did detect between 2 and 2.8VAC on this cap leg, which was swinging in the same manner as the display. This cap is connected to one of the IRC pins. Following it brought me to a shotky diode, one of two, which, apparently leaks full AC current through it and it goes into the regulator which then spreads it even more. I think the diode has failed and will be the first thing to replace, although it measures good.

[midsomerdave]

Aarrgh! What happened next??   

[w9gb]

Weller Document Repository (Scanned from my library) for
North American Weller Soldering products.  EU/UK had DIFFERENT handpiece designs.
BAMA Mirror
http://bama.edebris.com/manuals/weller/

Check the Control Boards: EC242, EC2000, EC2002 (EC214 control board in this directory)
EC Plug Wiring (late 1970s, 1980s) IMPORTANT ... since 5-pin Amp plug wiring was different until 1990s.

Distribute files as needed, but realize that Weller still owns rights ...
and I have copyrights for original repair notes.

g. beat
w9gb
chicago