Weller WMD-3 repair - Page 1
Forum section: electronics / repair

author: Baliszoft
author_rank: Frequent Contributor
timestamp: March 31, 2013, 11:07:08 am
content: So i got this soldering station and i thought it would serve me for a lifetime. I was wrong. The other day one of its channels stopped working intermittently and then finally failed permantently yesterday. I opened it up and have found no obvious signs of any damage.I thought that the problem is with the output stage (triac) of that particular channel, because the temperature was displayed correctly (i could heat the iron up with an other channel). The triac (for a channel) is driven by an optocoupler (TLP160J). The other side of this opto is directly tied to 5V and to the micro. The micro did not even want to turn the channel on (though the temperature display was fine).. After poking around the various components i have found that one of the diodes (SM4004) was faulty! This diode should do something regarding to measuring the resistance of (detecting?) the iron itself (just a guess though), because it is direclty connected to the heater of the iron and the circuit after the diode goes into an opamp then into the micro. So after replacing this diode (with the colsest match (S1M) i found in my cabinet ) the channel is working again. I have replaced ALL (12) of these diodes on the board as i do not really have got any confidence left in them. Neither in Weller.

author: nanofrog
author_rank: Super Contributor
timestamp: March 31, 2013, 07:47:29 pm
content: Glad you got it working again.BTW, when did you get it, and was it new (just curious)?

author: Baliszoft
author_rank: Frequent Contributor
timestamp: March 31, 2013, 08:05:43 pm
content: Quote from: nanofrog on March 31, 2013, 07:47:29 pmYes, i am "glad", too. It cost me an arm and leg back in 2009. I got it new from a local authorized dealer (was around usd 2200 with a DSX80 desoldering iron, HAP1 hot air pencil and WP80 iron). It was a "special" price, as they were clearing out new old stock items. It is constructed very robust and good quality no doubt, BUT using these "questionable" diodes (and who knows what else) renders all of these efforts completly unnecessary. These diodes were so heavily oxidized that my fresh leaded solder could not stick to them at all (neither with flux).

author: nanofrog
author_rank: Super Contributor
timestamp: March 31, 2013, 08:27:06 pm
content: Quote from: Baliszoft on March 31, 2013, 08:05:43 pmI wasn't aware that such practices (cheap parts) went quite that far back. My WD1 was purchased in 2008, but IIRC, date codes put production to 2006, and there are similarities in regard to cost cutting (24V power board appears to be outsourced from a company in Asia stuffed with the cheapest parts they could find).The unit I have wasn't nearly as expensive (have a bit under $400 in it with a second iron & stand), but I share your concerns over long-term reliability.

author: Baliszoft
author_rank: Frequent Contributor
timestamp: March 31, 2013, 08:41:48 pm
content: This is an old station (i have no idea about its original release date), it's got a 16C pic in it with plain eprom memory. I wanted to get a newer model oiginally (a 2ch one with the suction pump and hot air pencil), but they offered me this 3ch, but previous model for the same price. Considering that Weller is not really going into the right direction, i was happy with this older one, but it looks like you cannot really trust these either. :-( I also got a single channel WD1 too which i bought earlier than this. It is working OK (yet).

author: nanofrog
author_rank: Super Contributor
timestamp: March 31, 2013, 08:45:21 pm
content: Quote from: Baliszoft on March 31, 2013, 08:41:48 pmHave you opened your WD1?I'd be willing to pry mine open again for comparison's sake if you're willing, as I'm a curious person by nature.

author: Baliszoft
author_rank: Frequent Contributor
timestamp: March 31, 2013, 08:49:30 pm
content: Not yet, but i can do it. Just wait a bit. :-)

author: nanofrog
author_rank: Super Contributor
timestamp: March 31, 2013, 08:56:02 pm
content: Quote from: Baliszoft on March 31, 2013, 08:49:30 pmNo problem.You're welcome to send me a PM when you're ready and able.

author: Baliszoft
author_rank: Frequent Contributor
timestamp: March 31, 2013, 09:12:05 pm
content: Quote from: nanofrog on March 31, 2013, 08:56:02 pmHere. There is nothing much in it. However, i have discovered an SM4004 diode in it (just the same one which failed in the WMD3). It is not *that* well built like the older WMD3 though.

author: M. András
author_rank: Super Contributor
timestamp: March 31, 2013, 09:46:30 pm
content: i dont know what the hell cost this much on these stations, neither the stands but simply insane considering the contained items in it. Baliszoft you know the avarage incomes here in our lovely country compared to the prices of the weller tools

author: Baliszoft
author_rank: Frequent Contributor
timestamp: March 31, 2013, 09:58:42 pm
content: Quote from: M. András on March 31, 2013, 09:46:30 pmI would guess (!) that the total cost of the components/case/etc in the wmd3 was only 15-20% of the retail price.For the others: the price of that unit was half a year's salary of a hungarian worker (not engineer or anything fancy) back in 2009.

author: nanofrog
author_rank: Super Contributor
timestamp: March 31, 2013, 11:12:44 pm
content: Pic of the power board that's in mine.

author: nanofrog
author_rank: Super Contributor
timestamp: March 31, 2013, 11:36:45 pm
content: Seems the display & controller board differs as well.

author: Baliszoft
author_rank: Frequent Contributor
timestamp: March 31, 2013, 11:56:19 pm
content: Hmmm, i have no idea why do they have more variants of a simple unit like this. I got this in 2008, the date code is 40th week of 2007.

author: nanofrog
author_rank: Super Contributor
timestamp: April 01, 2013, 12:14:02 am
content: Quote from: Baliszoft on March 31, 2013, 11:56:19 pmEven though I also purchased mine in 2008, both boards in mine are older (38th & 40th week, 2006 for the controller & power boards respectively). Bought on sale, so presumed they sat on a shelf long enough the seller decided to cut prices to get rid of them (saved ~$70 from MSRP at the time IIRC).Given mine is simpler (fewer parts on both boards), I'd have to guess cost cutting may have gone too far to start with, and they made the necessary changes to fix it (or shifted to a new contract supplier that did). Makes the most sense to me at any rate.Boards in mine are damn simple, especially for the cost.

author: peter.mitchell
author_rank: Super Contributor
timestamp: April 04, 2013, 03:30:55 am
content: I guess the markup on these shows why chinese clones have such an opportunity/market to make money.