Weller WR 2 rework station - teardown

[mahi]

I had to desolder a great number of through-hole connectors and was not looking forward doing it with solder braid or solder sucker. Luckily a friend loaned me his brand new Weller WR 2 rework station with Weller DSX 120 desoldering iron which made the job a breeze. Even better, I was given permission to take a peak inside for a mini teardown!

Weller WR 2 specifications

• Temperature control: 50 - 450 .. 550 °C (range depends on tool)
• Airflow control suction: up to 18 l/min and a vacuum of up to 0.7 bar
• Airflow control blowing: up to 15 l/min
• Channels: 2 (up to 150 W per channel)
• Power consumption: 300 W
• Dimensions: 273 x 235 x 102 mm (l x w x h)
• Weight: 6.7 kg

Even though it's a new unit, the WR 2 is actually an older model which has been replaced by the (much more expensive) Weller WXR series. The WR 2 does not support any of the newer WMR or WX tools. Weller probably keeps the station to have a low cost rework solution with built-in pump. That does not make the station obsolete, though. There's still a great range of actively supported tools but keep it mind when considering this station.

The newest Weller hand pieces use fancy acceleration sensors to detect when it is not used to set back the temperature and preserve tip life. The WR 2 and its supported tools have none of that. Temperature setback and standby are supported but only through optional stands which detect the iron. At this price point it's incomprehensible these stands do not come with the station or tools by default.

A simple menu system is present to configure and store a few settings like setback/standby behavior and vacuum pre-feed/run-on. Per channel you can define 3 temperature presets which can be selected quickly - handy if you have frequently changing temperature demands. Under normal operation the display shows the actual temperature of the currently selected tool and in small the set temperatures of both channels. The quick temperature presets are shown for a couple of seconds after selecting a channel.

I did not really like the user interface, though. For example, switching a tool on or off requires pressing both the up and down buttons simultaneously but if not done precisely you either change the temperature or end up in the menu. A backlit display would be welcome as well.

Another thing I did not like is the size. It eats up a fair chunk of desk space but luckily its top side is flat so you can stack other tools on it.

Other than that the Weller WR 2 works as advertised and has plenty of power per channel: two 150 W irons can be powered at the same time. I'm not sure how well it works for hot air but the pump has plenty of suction power for desoldering. Forget about solder braid or the Soldapult Deluxe! Desoldering stations like this one are in a completely different league...

[mahi]

Lifted the lid... The pump and big transformer catch all attention. That explains the weight and size of the unit.











Construction quality is quite decent.

The pump is a rotary vane pump. It does not have manufacturer info on it other than Weller, but it is a Thomas G 24/07-N rotary vane pump (model 50311 or 50220). It does look like a quality pump, though. Quite different from what you find in most Chinese rework stations.

The toroidal transformer is a custom job for Weller by Noratel Germany AG similar to their RT300 series, but with 3 secondary windings. The transformer rates 300 VA with 230 V primary and 3 secondary windings: 24 V / 2 A and 2 times 12 V / 10.5 A.

The "cable" going over the transformer is actually a vacuum tube connection to a pressure sensor on the PCB.

[mahi]

Display and keyboard PCB:



There's not much to see on the display/keyboard PCB. An NXP PCF8576CHL LCD driver and that's about it. The display itself does not have any manufacturer markings but it's clearly a custom job for Weller. There are a few unoccupied islands left from the display. The layout suggests that it's for 2 LEDs and their current limiting resistors. I guess this is for a backlight that, sadly, never materialized.

The small connector in the top left corner is for the status LEDs above the output connectors.



A closer look at the main PCB:



The brain of the Weller WR 2 is a PIC18F6722-I/PT microcontroller. Just as with the Weller WHA 900 I took apart earlier there's an unmarked jumper near the microcontroller. I did not have the guts to try it out. I wouldn't be surprised if it clears calibration or other critical data for operation. Right from the microcontroller, on the edge of the PCB, is a seemingly unused 10-pin header which is most likely the programming interface. Exactly the same header was present in the WHA 900.

The (de)soldering tools are powered through the two TO-220 BT138X-600 triacs and their KTLP160J triac drivers - one for each channel. The 5 V power supply for the electronics is provided by the TO-220 MIC2937A 5.0WT low-dropout voltage regulator in the top left corner. In the center of the board is a TO-220 IRLI530N power MOSFET to drive the pump. In the lower left corner is a pressure sensor but sadly it did not have any part number markings on it. It is used to measure the vacuum during desoldering.

The main PCB is clearly shared with the higher end WR 3(M) which features 3 channels with up to 200 W per channel, an extra pump and USB connectivity. The islands for the third output are visible below output 2, the islands for the USB interface are on the lower right edge and the islands below the heatsink suggest there can be quite a few more TO-220 power houses.

At first I was a bit puzzled by the amount of unpopulated TO-220 components. The WR 2 has 2 triacs and the WR 3(M) has only one extra channel, but there are 8 open TO-220 triac positions on the WR 2 PCB making up for a total of 10 triacs (ignoring the right most unpopulated TO-220 because that's clearly a voltage regulator judging by the layout of the components around it)? In fact some of the pins on output 1 and 2 go to the unpopulated TO-220 triacs. So even the available outputs of the WR 2 clearly do not support some things. What's going on?

The higher end WR 3(M) supports more tools like the WMR active tip series. These are 12 V tools unlike the traditional 24 V Weller tools. The 12 V tools have 2 triacs per channel to support tools with two heating elements (tweezers). So that's one triac per channel for the high power 24 V tools, and 2 triacs per channel for the 12 V precision tools - 9 triacs in total. But wait... There are 10 triac positions on the PCB? That's because output 1 has an extra 24 V triac for the HAP 200 hot air pencil (it has two heating elements). That's why the HAP 200 cannot be used with the WR 2 and even on the WR 3(M) it works only on output 1.



That's it! I hope you liked this mini-teardown!

[hugos31]

I have this 24v :                       What motor do you recommend???  Will be the one indicated   

[hugos31]

ebay  1000  eur   

[KL27x]

That's a sexy piece of equipment, inside and out. Great pics. I love that transformer and vacuum pump.

[darkstar49]

didn't want to disassemble everything, but here a view on the corner of the WR3 PCB, just moved it so that I could replace the fuse (F1) of the pump.
Oddly, the pads are populated, as well as the USB interface...

[free_electron]

pump is most likely a custom jobbie with a Buhler motor.
i have one of these stations. rock solid.

[eeviking]

The higher end WR 3(M) supports more tools like the WMR active tip series. These are 12 V tools unlike the traditional 24 V Weller tools. It seems they have their own triac drives (on different pins of the output connectors). So that's 2 parallel triacs per channel for the high power 24 V tools, and one triac per channel for the 12 V precision tools - 9 triacs in total. But wait... There are 10 triac positions on the PCB? Honestly, I'm not sure about the 10th. I had already put the unit back together when I realized I missed one and I can't make up from the pictures where it goes to (it's the fourth TO-220 from the left in the top view picture).

Could the last triac be for an extra pump for the vaccum pick-up channel on the WR3M ?

Also it's not two parallel triacs for 24V but two independent 12V triacs per channel for the micro tweezers that uses two 12V heaters.

[darkstar49]

And I didn't realise that, but my WR3 has an electro-valve in front of the pump !!
Looks to me like that WR2 will always blow and suck simultaneously (I mean, on the outside terminals)... WTF

[Kirkhaan]

Great teardown, thanks!

[surfaced]

Has anyone else done a backlighting mod like this for a WR2 or WR3M(E) series rework station?

Is it as simple as adding any LEDs are resistor dividers? Would you also recommend adding a reflector or diffuser? Any tips would be appreciated; can't find any other documentation on such mods around the internet.

[mahi]

Has anyone else done a backlighting mod like this for a WR2 or WR3M(E) series rework station?

Is it as simple as adding any LEDs are resistor dividers? Would you also recommend adding a reflector or diffuser? Any tips would be appreciated; can't find any other documentation on such mods around the internet.

After doing the teardown and noticing the unpopulated islands for the backlight, I mentioned this to the owner and we looked for a compatible backlight together. On Aliexpress we found a (different) display with the same dimensions and a backlight (link). The backlight is pretty much a drop-in replacement (you have to remove the red and green LEDs temporarily to slide the backlight underneath the LCD). However, it didn't work out well. The reflective film at the back of the LCD is almost opaque, so even at max brightness the display was very dim and unevenly lit.

LCD displays that are meant for use with a backlight have a translucent reflective film at the back. The display used by Weller is clearly not for use with a backlight.

In theory one could remove the opaque reflective film and apply a translucent reflective film to the display, but it's very difficult to remove just the reflective film and not take off or damage the polarizer film underneath which would ruin the display. Sure, polarizer film can be purchased as well, but in earlier experiments with (a lot of) polarizer films from Aliexpress, I found that none come even close to offering the contrast, blackness or viewing angles of the original films on LCD displays. Not wanting to risk to ruin a perfectly fine soldering station, we decided to not pursue this further and leave the backlight out.

The WR 3M hugos31 found on eBay, must have had a mod like we were doing. Judging by the "hotspot" on the right side of the display, at least one additional led was added to crank the brightness up (the backlight has 2 LEDs on the left side). I'm not sure I like the hotspot on the right, and it still does not look very bright...