Weller WR3ME channel 1 won’t shut off - found it! - Page 1
Forum section: electronics / repair

author: mkinn
author_rank: Contributor
timestamp: August 18, 2025, 04:25:30 am
content: Finally found the problem, it had a shorted diode on Ch1 near the front panel connector. I removed it, but can't find anything online about it. Does anybody know what diode is used across pins 3 and 4? I suspect a protection zener diode, but it could be anything, I still can't find a schematic for ANY Weller station from this time. They all just show an image of the PCB layout, where the diodes are on the board. I did find a schematic for a DIY station for Weller RT tips showing a pair of BAS316 100V 250mA SMD High speed switching diodes, with cathodes reversed, + and - shunting to Gnd after a 5.6K ohm buffer resistor in series with the the input of the temp sensor op-amp. There's a 1M ohm pull-up resistor to 3.3V VDDA before that, but I'm not sure how that circuit is supposed to work, unless they act as protection diodes. I guess the temp sensor voltage never exceeds ± 0.7VDC? They are not the glass type on the Weller PCB. Does anyone have an old, junk Weller PCB with these diodes on it? Or a part number/where to buy? the only thing I could find similar was a Vishay BAV303-TR3, but I'm not smart enough to make that substitution without asking here 1st...Photos show the glass diode before & after removal, the rear of the PCB, and that DIY schematic.

author: mkinn
author_rank: Contributor
timestamp: September 03, 2025, 04:21:58 am
content: Well, no replies from this forum, so I swapped the connectors from the channel 1 and 2 front panel jacks at the main board, to check whether it was the main board or the wires/sockets. I then ordered and replaced the 2 diodes with the Vishay BAV303-TR3 diodes, much smaller than the original ones, and MUCH harder to hold in place, even with non-wetting Weller RTWPS tweezer tips. Channel 1 is now fixed, works perfectly. This will save you ~$800.00 for a new main board, if yours fails with this problem and you don't know where to begin. All the triacs and opto-isolators tested the same, and all work perfectly. I would still ask if anybody EVER finds a schematic or internal parts list, PLEASE post it here, you will get a BUNCH of thank-you's! Also, still looking for a way to hook up a footswitch to these WR3M stations. the catalogs say it's possible, and some resellers even say that the T0051312099N footswitch is SUPPOSED to come with the T0058738850 adapter. I've yet to find one.

author: mahi
author_rank: Regular Contributor
timestamp: September 03, 2025, 09:02:39 am
content: Thank you for describing the repair of your WR 3M(E)! Might come in handy if someone faces the same problem.I have never seen schematics for the Weller WR 3M. I only know of the PCB component layout that a user got from Weller to identify a blown fuse on the PCB (attached). Not that helpful without component list or schematic.As for the foot switch... I was not even aware the WR 3M supported a foot switch, but I checked the user manual and, sure, it is listed as an accessory. The user manual nowhere mentions how to use it. There's no dedicated foot switch port on the back of the WR 3M like on some other stations. So, how is this supposed to work? Does it connect between the handpiece and the WR 3M with the adapter?I doubt the adapter comes with the foot switch. The foot switch part number corresponds with that of the Weller WRS3000 Repair System. That station is much older than the WR 3M and does actually have dedicated foot switch ports at the back. Why would the foot switch of the WRS3000 come bundled with an adapter for a station that did not yet exist at that time.Also note the foot switch can be used only with the hot air pencil. I understand why you'd want a foot switch for hot air, but do you think the HAP 1 or HAP 200 hot air pencils are any good? In my opinion the air volume and thermal power is way too low for serious work. I think the WR 3M is a great station for tweezers and vacuum desoldering, but for hot air you are much better off with a dedicated hot air station.

author: mkinn
author_rank: Contributor
timestamp: September 04, 2025, 03:51:26 am
content: The WR3ME doesn't have a button or a port for the WVP vacuum pickup pen, but the WR3M does. I have both of them. I was hoping that there was a way to hook up a footswitch to the USB jack, maybe the adapter would shed some light on that. If I had a schematic, I could probably do some testing in that regard. Some data capture with GPIB on an o'scope might be rewarding using the Weller control/logging software install CD. If I do this, I'll publish the results here for IO protocols. I was hoping to find all this out before anyone who actually knew anything about this topic left the chat. Otherwise, it might be easier to just add a 1/4" or 1/8" mono jack on the back and run wires in parallel to the front panel VAC button. You could then just use ANY footswitch off Amazon with the correct plug on it. I'd probably add a fast acting 7.5V Zener diode on that wire at the PCB for static protection. The WMA3V/WRS2000 has a wire that changes what the footswitch does depending on which tool you connect to the 7 pin DIN plug. Vacuum for the de-soldering tool, air for the hot air pen, or vacuum for the WVP otherwise. Pretty cool! For special needs, maybe?

author: mahi
author_rank: Regular Contributor
timestamp: September 04, 2025, 02:36:11 pm
content: The foot switch can't be connected to the USB port. The Weller WR 2 lists the same foot switch and adapter as accessories, and it does not have the USB port.The only way I can think of is that the adapter is connected between handpiece and station. The foot switch will be in parallel over the finger switch of the HAP 1/HAP 200. So, I wouldn't waste my time with the Weller foot switch and adapter...