Weller WD1 Discussion and Repair

[quanttrom]

I'll just leave this right here in case it's ever useful to anyone..

I got my hands on a broken Weller WD1. This is the rather basic variant with single output and no USB connectivity but it is still a rather nice soldering iron IMHO.

I managed to get the schematics of it and I will try to explain the working of it to the best of my understanding. Corrections and discussions are welcome.

The soldering iron has a transformer with 2 output voltages on it. One is 12V the other is 24V. There are 2 separate boards. First PCB includes all the 24V electronics while the second board is the control and user interface.
First board:
The 12V AC output is rectified with a single diode and then fed straight into the control PCB.
The 24V AC is used to power the heating element. A TLP160J  optocoupler (http://www.toshiba.com/taec/components2/Datasheet_Sync/210/4350.pdf) is used for isolating the control circuitry from the heating circuitry.  A BTA12 triac is used to turn the heating element on and off.
The zero-crossing detection of the 24V AC is done using a 100k/100k voltage divider with clamping diodes, etc. The output of this is fed into the control board into the /INT1 (pin 9) input of the micro.
Control Board:
The 12V DC from the first board is reduced to 5V through a linear regulator. Run of the mill 7805 (78M05) .
The whole design is based around a PIC18F4620. The buttons on the faceplate are directly connected to the micro. The LCD display is driven by a PCF8576 driver (http://www.nxp.com/documents/data_sheet/PCF8576.pdf) . The PIC and the LCD driver communicate through an I2C bus.

There is some analog circuitry on the temperature probe output that comes in from the soldering iron pencil. It is based around MCP601 op-amp. The positive input is connected through a 1k5 resistor to microcontroller pin 5 -  RD7 (I assume they use it as PWM output from the micro) and fed in the opamp
The opamp is used to prove a (what seems to be rather large ~31) gain to the signal from the temperature probe.  The output of this circuit is fed into pin 20 (AN1) where they use the build in 10-bit AD converter.

There are some other feedback signals used but I am not sure what their purpose is. One is fed into AN4 (pin 24) and another one into RD2(pin 40) .

Header X3 is used for programming.  TE Connectivity 8-215464-0.

And that's all she wrote !

The PIC was damaged...somehow..on the unit that I got. I was able to make a programming header and use it to read the firmware from another good unit and program it into this one. A PICkit2 programmer was used. Overall a rather painless process once I acquired a new micro and the proper connection header. The second unit wasn't mine so I wouldn't be allowed to solder wires and butcher the whole station.

10 bucks and a couple of hours of fidgeting around trying to get all the info proved very useful

Blog post + pics : http://www.quanttrom.com/2013/12/hardware/weller-wd1/weller-wd1-repair/

[M. András]

it would be good to be able to speed up that display it slow as hell and most of the times i dont know what temp is it displaying but not the actual, while the wd1m i have outputs the actual temp trought usb to the weller software intrestingly

[kripton2035]

it is quite extraordinary that you were able to read a PIC' firmware out of a commercial product...

[M. András]

haha i doubt they did even brother to prevent reading it out, wd1m has the option to upgrade the firmware trough usb but there is no firmware anywhere on their sites and doesnt even reply for for it

[quanttrom]

The USB is actually done using a serial to USB converter board. There isn't anything magical about it. I believe a different firmware load is also required.

I've hooked up an oscilloscope to the TX/RX pins that typically go to the USB board and I don't see any kind of signals on them. There is a possibility the software needs to send some magical init sequence before they start outputting info.

Actually I am kind of curious. M. Andras would you be interested in reading out the firmware from your WD1M ?

[nanofrog]

The USB is actually done using a serial to USB converter board. There isn't anything magical about it. I believe a different firmware load is also required.

I've hooked up an oscilloscope to the TX/RX pins that typically go to the USB board and I don't see any kind of signals on them. There is a possibility the software needs to send some magical init sequence before they start outputting info.

Actually I am kind of curious. M. Andras would you be interested in reading out the firmware from your WD1M ?

According to the manual I have, the WD1 & WD2 are upgradeable to an M version by adding the USB interface board.

[M. András]

if you tell me how to do it without taking the thing apart, cos its under warranty for a 1 and a half year, their firmware upgrade tool as i remember only uploads and wont read it back, as for just a serial  to usb coverter its right a small raiser board mounted with a rivet dangling freely from the plugging force of the mini usb cable

[quanttrom]

I don't think you can do it while it is under warranty.

That said, I think nanofrog is right. It is very likely that I just have to pull a signal high or low and it might start spewing some information on the serial port. I will download and have a look at the WD1M software.

[M. András]

pls link it if you find somehow a firmware for it, as i remember it has 1.00 or 1.01, but i highly doubt it


edit: btw i think there are some component differences between the 2 models only the M model supports the wrmp pencil which has a laser engraving on the handle 12V/55w, now the station supposed to be 24v output

[nanofrog]

edit: btw i think there are some component differences between the 2 models only the M model supports the wrmp pencil which has a laser engraving on the handle 12V/55w, now the station supposed to be 24v output

You're thinking of the WXMP, which is 12V. The WRMP is 24V (40W), and designed for the WDxM & WR3/3000M series stations.

I presumed that once a user upgraded a standard WD model to an M version, load the software, and connect the station to the computer, it would download the necessary firmware to support the WRMP & WMRT hand pieces. Perhaps the firmware is already present from the factory? 

[M. András]

if its enough proof for you

[nanofrog]

if its enough proof for you

Wonder what's up with this?

I say this, as I double checked with Apex's site (Weller) prior to posting, which states that the WRMP = 24V.
Source: http://www.apexhandtools.com/brands/CF_Files/model_detail.cfm?upc=037103209047. Same info is duplicated in their brochure (click the literature link).

WTH Weller? 

[M. András]

it had a dedicated station and a vertical stand and these are obsolote now that version was 24v
http://www.weller.de/products/product.php?pid=52

[nanofrog]

it had a dedicated station and a vertical stand and these are obsolote now that version was 24v
http://www.weller.de/products/product.php?pid=52

I knew they changed the stand, but hadn't heard or seen a change to the iron or station.

Wonder why they haven't updated the US site? Perhaps the older 24V version is still being sold here (find it odd from a systems/manufacturing POV since their owners are all about cutting costs, but possible)? 

[M. András]

it was the wrms kit what used the 24v version of this, i dont know if the wxmp different or not but i dont know the reason too why its not supported by the wd series only the wx stations

[nanofrog]

it was the wrms kit what used the 24v version of this, i dont know if the wxmp different or not but i dont know the reason too why its not supported by the wd series only the wx stations

I'm guessing the voltage differences (power boards weren't designed to switch between 12V & 24V irons). At least here in the US, searching (both Apex and distributors), all indicate that the WRMP is coming up as 24V and is compatible with the WD1/2 M variants.

Funny thing is, the link I gave from Apex, states the information is for the WRMP, and the photo is of the WRMS (check the larger image). I know companies don't always use the correct image, but rather a common image for a series/product family, but I'd hope the specs listed for the stated P/N are correct.

Currently, I'm trying not to convert my unit given Weller's QC issues (seen issues of both irons and power heads dying in this and later series; very recent news to find the WMD series is the same).

[Zapro]

I do believe, that you cannot modify a WD1/2 for the WMRP pencil. The WMRP pencil does use a K-type thermocouple, and not a NTC like in all the other stations.

I have a WD1M station, that I have taken apart to see how it works, similarly, i've taken an WD1 station apart to see, what the differences is.

There is no thermocouple-amplifier in the WD1/2 station, so it cannot read a thermocouple iron (e.g. WMRP)

So, it's not all up to software differences.

// Per.

[dungad]

Hi All, I'm new to the forum and need a bit of help.
I've found an old welled WD1 that someone removed bits form the power board(I assume only the BTA12 is missing and have a good idea of where it needs to go) but can someone please post a photo so that I can compare and see what else may be missing form my unit?
Cheers,
Dan

[quanttrom]

would schematics be adequate?

[dungad]

Yes, schematics will help more. Can you point me to where I can find them?

[nanofrog]

Pics can be had too, in the following thread: https://www.eevblog.com/forum/reviews/weller-wmd-3-repair/msg210603/#msg210603

Please note however, that the boards posted by myself and another member (Baliszoft) are different from one another, so there's at least 2 PCB revisions for that model. Specifically, it's the BTA12 that is one of the parts that has a slightly different location. So you may need to trace out your particular board.

Hope this helps. 

[nanofrog]

Here's the schematics for the WD1...

[dungad]

Hi nanofrog,
Thank you for the additional information, my WD1 unit is like Baliszoft's one.
Looks like I'm only missing the triac, will post my result once I get the new triac installed.

[pinkman]

I recently acquired an WD1 station which works fine for a while, but ends with the degree (oF) indicator flashing and the iron OFF. 

Sometimes turning the unit off/on or performing a factory reset corrects this problem for a while, but it always comes back.  I have tried swapping in a brand new iron and it has the same symptom, so it appears that the problem is internal.

Has anyone encountered this problem?  I downloaded the schematics and I'll analyze them later.  I suppose it's time to start poking and prodding this little monster.

[SLJ]

Not to sound obvious but did you check the settings for standby and auto-off time?