Weller WR3M Vacuum Pump broken ?  - Page 1
Forum section: electronics / repair

author: darkstar49
author_rank: Frequent Contributor
timestamp: August 10, 2020, 03:10:52 pm
content: Hello,the vacuum pump of my WR3M just died, after having made some strange noise... the other parts of the station seems to work OK.The red and green leds around the 'Vac' label (on the front, to the left of the screen) are blinking when activating the pump (well, trying to...).Any advice or piece of real-life experience to share before I open the beast ?? ;-

author: mahi
author_rank: Regular Contributor
timestamp: August 10, 2020, 06:05:32 pm
content: You may find myWeller WR 2 teardownuseful. It shares a lot with the WR 3M. The pump is the same.The Weller part number for the pump is 0058739707 (supersedes 0058739704). Better hope the problem is with the MOSFET driver instead of the pump because the price is quite hefty...I did not see any manufacturer markings other than Weller on the pump but I don't think Weller makes it. Maybe you can find an alternative 24V rotary vane pump that fits although these pumps tend to be fairly pricey. The user manual states a maximum vacuum of 0.7 bar and a maximum delivery rate of 18 l/min.

author: darkstar49
author_rank: Frequent Contributor
timestamp: August 10, 2020, 07:52:32 pm
content: Thanks a lot for the info !!!here's what happened to mine.... somehow unbelievable !!!!!Don't know what blew up, but removing the fan didn't help, something's broken...I mean, the station works OK, just the pump not (got the DSX80 on channel 3 when it happened... that channel still heats the DSX, but the actuator doesn't trigger anything, no noise or so, apart from the red light near the 'Vac' label on the front-panel...)Just drove the pump 24V, no issue, runs perfectly... so the issue is on the board...

author: Fraser
author_rank: Super Contributor
timestamp: August 10, 2020, 09:14:51 pm
content: To me that looks like an over speed failure of the cooling fan. The motor rpm rose to the point that the blades flexed towards the rear ventilation slots and hit them. I would suspect either a shorted through speed controller or a failure in the controller circuit that drives the active element controlling the fan.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: August 10, 2020, 09:19:19 pm
content: You should test whether the air pump impeller (not the cooling fan) is still attached to the motor shaft. It acts like a form of air break so a failure in the air pump impeller can cause an over speed event in a motor. Powerful motors can hit very high RPM if the Primary load is removed from them. Just look at modern Radio Control model electric motors.... amazing “No load” RPM capability.You need to take a close look at the circuit that drives the pump motor. Is it a simple on/off type of motor control or is it driven by PWM ? A simple on/off motor switch would not normally cause an over speed situation but a PWM drive failure to 100% drive could if the motor is never supposed to see 100% drive.Fraser

author: darkstar49
author_rank: Frequent Contributor
timestamp: August 10, 2020, 09:42:44 pm
content: as stated, pump works alone, but never starts in the WR3... just checked voltages on the IRLI530... 2.4V between pins 1 & 2, as well as 1 & 3 when activating the pump with a HAP200... WTF?I'm really dumb at electronics,, I'm more a software guy... so given the circuit depicted in the mentioned WR2 article, what could be wrong here

author: darkstar49
author_rank: Frequent Contributor
timestamp: August 10, 2020, 09:44:17 pm
content: Quote from: Fraser on August 10, 2020, 09:14:51 pmThe fan sits directly on the shaft of the pump... no control logic whatsoever...And btw, the pump is driven on/off, nothing more... just the timing (pre/post running) is configurable, and there's also a limit to prevent continuous usage, as well as some protection linked to the pressure (for vacuum), to prevent the pump from running for too long with dirty filters. But none of those apply here...

author: darkstar49
author_rank: Frequent Contributor
timestamp: August 11, 2020, 07:34:20 am
content: Got it... Weller called back this morning, the F1 fuse is blown.I cannot say enough how seriously "service" is being taken in south Germany !!! ('lived there for 7 years a while ago)Not many companies would offer support, schematics, and eventually free parts for a 10-years old device...Will definitely consider a WXR3 soon...

author: Fraser
author_rank: Super Contributor
timestamp: August 11, 2020, 09:38:37 am
content: Great news but that fan did not get shredded by a blown fuse so something else is going on within your unit.Fraser

author: darkstar49
author_rank: Frequent Contributor
timestamp: August 11, 2020, 09:45:58 am
content: Quote from: Fraser on August 11, 2020, 09:38:37 amThat's for sure !! But I guess we'll never know... maybe the "extreme" heat these days (36+°C) have led to the blades becoming softer and bend to the point they touched the casing...?But nylon blades were a bad idea from the start... ABS or something similar would have been much better, as much stiffer, given the tight tolerances inside the casing.A pitty also that the propeller itself is not orderable (outside from the pump's assembly for 400 bucks !!!), although Weller was quite helpful, and said they'll look in their stock of dead pumps...

author: Fraser
author_rank: Super Contributor
timestamp: August 11, 2020, 11:01:02 am
content: I am pleased to hear that Weller are trying to help you. I had wondered about heat affecting the fan blade rigidity but thought Weller would have considered heat in their design as these units are used all over the World and some regions get very hot indeed. As you say, a poor choice of material. I like good old Aluminium fan bladesThankfully a large range of cooling fans are available for other equipments and maybe one could be modified for your needs if Weller cannot supply the part. There would also be the option to but a common electric fan of the type used in computers etc and either install it in your station as an independent cooling fan or dismantle it and modify the fan section hub To mount on your motors shaft. There could even be a good match of fan available off the shelf from a central heating boiler blower motor cooling fan or similar. The diameter will be the challenge as many are larger than your fan.Can you tell us the diameter of the fan and the motor shaft hole diameter ?There is always the option of a 3D printed fan using ABS if all else fails.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: August 11, 2020, 11:07:42 am
content: There will be a choice of 3D print designs for motor cooling fans on Thingiverse etc. Here is just one I stumbled upon....https://www.thingiverse.com/thing:3680874You could get one made by Shapeways etc to get a nice quality product at a good price.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: August 11, 2020, 11:14:52 am
content: I think I found a search term fir the sort of fan that you need. Look for “hairdryer fan” as that will be the smaller diameter that you need. Make sure the fan blade direction is the same as your original fan and you will need to drill the central mounting boss to your motors shaft dimensions. This is a very inexpensive solution. The option to disassemble a standard small low voltage computer fan remains a good backup plan as well.https://www.ebay.com/itm/Small-Power-Mini-Plastic-Fan-Blade-4-6-Leaves-For-Hairdryer-Motor-Hot/283208600839?var=583634569990

author: Fraser
author_rank: Super Contributor
timestamp: August 11, 2020, 11:18:44 am
content: https://www.ebay.com/itm/1-Pcs-Small-Power-Mini-Plastic-Fan-Blade-6-Leaves-For-Hairdryer-MotorW-MO/313165968854?epid=9035389617&hash=item48ea2575d6:g:84wAAOSwDwhdzLvg

author: darkstar49
author_rank: Frequent Contributor
timestamp: August 11, 2020, 11:28:12 am
content: The shaft is 4mm, and there's 15mm between the pump's fixture plate (at the back of the pump) and the casing, and the shaft extends 10mm from there...The propeller itself is 60mm in diameter.So you basically need a propeller that is 9-10mm thick, and 60mm wide, and that will leave you with 5mm spacing... (hence, no 'bending' permitted !!)There are many propellers available from 60mm cooling fans, but those have a central motor, so indeed some sort of (printable) adapter will be required, or you could also fill the center part with resin and bore a 4mm hole, but you'd have to be very precise to prevent excessive vibrations...The most 'realistic' option if one can't get his hands on a propeller from Weller, would be to cut the shaft at the back of the pump (to free the 15mm space behind the pump), and install a 60mm fan (5V models typically draw less than 1W, and the 5V LDO that feeds the board is a 5W model, so that should be OK... but 12V might also be available, TBC...)Or couple it with the pump (24V), and use this:https://www.amazon.com/WINSINN-Brushless-Cooling-Computer-Graphics/dp/B07GX9P48F

author: darkstar49
author_rank: Frequent Contributor
timestamp: August 13, 2020, 10:49:52 pm
content: Pump is back online (F1 replaced), but just a last feedback from Weller:while the idea of a (possibly 24V) fan at the back seems cool, I requires some butchery (in particular, cutting the pump's shaft on the back of the pump's assembly), not complicated but... Weller made it very clear : if a unit comes in for servicing, whatever the problem, it needs to leave in its original state... in other words, one might have fixed the pump's fan, but if he/she has to send in the unit for some other, unrelated problem, Weller will restore the initial state, i.e. replace whatever is needed to get the unit in its original state, whether those (other) components did work or not...So unless there's 0 zero chance of ever sending the unit back to Weller, I'd leave it 'as is'...

author: Fraser
author_rank: Super Contributor
timestamp: August 13, 2020, 11:03:35 pm
content: So the question remains..... why did the fan impact the rear casing and can Weller offer a replacement fan ?Do Weller have anything to say about this unusual, and embarrassing, failure in their equipment. I hope they can be shamed into providing a new fan for your unit but what is to prevent it happening again ? This is an unusual failure that I hope Weller take seriously.It would be worth checking the environmental temperature rating of the unit in the user manual and ask Weller why their fan appears to have become distorted whilst running within its environmental specification. Could it be that the fan started to slide off of the shaft and that caused the impact against the rear casing ? If this is a possibility, I would add something to the fan central boss or motor shaft to prevent a re-occurrence. I would use open or blind press fit starlock washers as pictured in the attachment.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: August 13, 2020, 11:15:06 pm
content: Another option to prevent a re-occurrence might be to move the whole pump assembly bracket further forward towards the front panel to increase the fan to rear casing clearance distance. That looks to be a relatively simple mod that can be reversed at any time for servicing by Weller.Fraser

author: darkstar49
author_rank: Frequent Contributor
timestamp: August 14, 2020, 09:16:48 am
content: Weller committed to provide a new fan at no cost, but I'm not too sure that this is "by policy", but rather because I had a very constructive personal contact with one of their support engineer...And again, the problem is not that the fan did slip somehow along the shaft, the fan's centrepiece was still perfectly against the back of the pump assembly, but the blades had deformed to the point their tips collided with he casing, check the attached pic...On the other hand, I don't know why this happened to me... but if this was a 'structural' problem of all the WR stations, I guess this would already have been mentioned/discussed elsewhere, and it wasn't, so my belief is that this was an isolated issue...

author: Fraser
author_rank: Super Contributor
timestamp: August 14, 2020, 10:10:57 am
content: I am pleased that Weller are going to provide a fan. As you say, it may be an isolated incident. It is certainly unusual for a fan to distort like that.All the bestFraser