WESD51 Upgrade? - Page 1
Forum section: electronics / projects

author: dbranger94
author_rank: Newbie
timestamp: December 13, 2024, 03:56:41 am
content: Hello, this is my first post on here. I was told this is the place to ask this question, so here goes.I was wondering if upgrading the triac in a Weller WESD51 or even the newer WE1010NA would result in any improvement? Perhaps warmup time or something. It looks like the current triac is a BTA12-600 and I have a couple of BTA16-600 triacs laying around. I thought it might be a fun project, unless it's too much for the heating element to handle. Any thoughts? Even a 12A triac seems to be a lot for a 70W iron, but I'm not sure about the relation between the triac and the heating element. I assume the element isn't even pulling enough current to utilize the 12A triac? Thanks for any info.

author: elektryk
author_rank: Regular Contributor
timestamp: December 13, 2024, 05:21:02 am
content: It may change forward voltage a bit, but that difference probably won't be noticeable.

author: pqass
author_rank: Super Contributor
timestamp: December 13, 2024, 05:56:28 am
content: The transformer secondary voltage output is fixed. The heater (iron) resistance is fixed. Therefore, the current through (and power consumed by) the heater remains the same regardless of the current rating of the switch (triac). A switch that is rated higher than the load current demands is just extra safety. All components of a circuit (except the load) need to be rated higher (plus margin) than the fuse otherwise the weakest link will break first (before the fuse).The WESD51 50W station uses the PES51 iron. I made my own station controller with this iron and run it at 20V (vs 24V in the WESD51) thus pulls 2A and takes about 25 seconds to get to 250°C. I find this acceptable. If your WESD51 takes longer than this then it's due to the software (PID algorithm).

author: jwet
author_rank: Frequent Contributor
timestamp: December 13, 2024, 06:51:50 am
content: There is also a PID loop in software in a small PIC microcontroller that is responsible for maintaining control. Even if you got into the source code of the PIC, it can't do much more. Its isn't a hardware limitation, its a design limitation. The heater, heats the tips through a imperfect thermal interface which has a thermal resistance and lag associated with it.High performance irons (JBC, etc) have a much more direct thermal connection between the heat source and the tip, Weller's higher end irons have this property too but they cost a lot more. With the thermal design of the PES51 or WE1010, pushing the iron harder will just make it unstable- there is lag in the thermal path and the ramp is slowed down to maintain stability.I think these types of irons are really perfect for what I do- medium to fine rework on boards, not production. These "direct coupled irons" can pour in more heat than I need at times. I kind of like this higher impedance source of heat- it doesn't get away from me.I've seen Dave Jones do tests where he is heating up 10 square inches of copper clad- this is a very rare case for me. If I need to do this, I have a 20 year old Weller gun that can put 250W into a solid block of copper. I prefer the control with an Iron like the WE1010- its predictable. The ramp time is part of the trade off.My personal opinion, open to dissenters.John

author: dbranger94
author_rank: Newbie
timestamp: January 10, 2025, 06:18:37 pm
content: Thanks for the replies. After staring at the schematic a bit longer, I came to this same conclusion. The resistance of the heating element had to be the current limiter in this design.