Weller WSD-81 behaves strange (loses temperature) - Page 1
Forum section: electronics / general

author: Arp
author_rank: Unknown
timestamp: May 09, 2014, 11:28:57 pm
content: Been happening quite frequently. While soldering, suddenly the led wont melt. I look at the station and see the temperature has fallen to around ~140C. I have to "reboot" it my powering it off and on. Then the temperature increase back to where I want it. Is this some feature I'm unaware of or maybe there's something wrong with it? Anyone experienced this or something similar?

author: nanofrog
author_rank: Super Contributor
timestamp: May 10, 2014, 12:46:38 am
content: I'd check for an intermittent connection first between the iron and the iron's connector on the power unit (particularly the latter). Could have a cracked joint, which has been reported before on Weller stations. Easy fix if this is the case.

author: Arp
author_rank: Unknown
timestamp: May 10, 2014, 02:10:08 pm
content: Could that relate to older stations? Repaired an old WTCP-S some weeks ago. The station started humming and the fuse blew. It was the isolation around the wires inside the handle that had ages and deteriorated so that the copper wire was touching the metal around it.This station is pretty new. Bought it in 2012. Going to use the warranty if necessary, but still curious what it might be. Maybe it's overloaded, just like with the older station, but goes into a failure mode instead? I'm unable to provoke this from happening by twisting it around and hitting it in the table

author: nanofrog
author_rank: Super Contributor
timestamp: May 10, 2014, 06:18:27 pm
content: Quote from: Arp on May 10, 2014, 02:10:08 pmNot that I'm aware of.Only know of this issue occurring on the newer stations (lead-free joints).Quote from: Arp on May 10, 2014, 02:10:08 pmNice.And it gives you a backup.Quote from: Arp on May 10, 2014, 02:10:08 pmI'd open it up and check for cracked joints, particularly on the connector. Reflow if you find any bad ones (maybe go through the effort of sucking/wicking the lead-free off, and use lead based solder). Past that, it's up to you, but I'd probably send it in if it's still under warranty.You could also request schematics if you want to fix it yourself (they did this for me, though it was out of warranty when I made the request FWIW).Overloaded, it should blow it's fuse just as your old one did. As per not being able to reproduce the issue with physical jarring (unit closed I presume), I suspect it's thermal cycling that's causing it. Maybe open it up and flex the actual PCB if possible.

author: Arp
author_rank: Unknown
timestamp: May 11, 2014, 03:33:19 pm
content: Probably gonna have a sneak peak as there is no warranty void sticker . Don't like the hassle of warranty repair and it would be another repair for the resumeThanks for the heads up

author: retemitlum
author_rank: Newbie
timestamp: May 11, 2014, 05:05:45 pm
content: Sounds like the standby function is activatedFrom the manual :Standard setbackIf the soldering tool is not used within a period of 20 minu-tes the temperature will be automatically reduced to astandby temperature of 150 °C (300 °F). After threesetback periods (60 min.) the ”AUTO OFF” function will beactivated and the soldering iron will be switched off.Activating the standard setback function:When switching on the unit press the ”UP” button until ”ON”appears in the display. The setting is saved when the "UP"button is released.Use the same process to switch the unitoff. ”OFF” will appear in the display (state upon delivery).

author: Arp
author_rank: Unknown
timestamp: May 11, 2014, 05:23:32 pm
content: Quote from: retemitlum on May 11, 2014, 05:05:45 pmI was sure it didn't have such a feature. I'm never gonna be sure againStill curious what "not used" means as I was using it. Tonight I had to power cycle it 3 times. Will have to check that manual. Thanks for the info. I'm going to go stand in the corner now

author: nanofrog
author_rank: Super Contributor
timestamp: May 11, 2014, 08:27:40 pm
content: Quote from: retemitlum on May 11, 2014, 05:05:45 pmCompletely forgot this station has this feature.But it's the frequency of having to power cycle it that still has me wondering if it's still something else though.Quote from: Arp on May 11, 2014, 05:23:32 pmFirst, go ahead and disable theSetbackfeature (text is inretemitlum's post), and see if by chance that solves your issue. "Not Used" *might* be the message displayed when it's gone into Auto OFF, but would think "OFF" or "---" would be displayed instead as it fits on the LED digit display if there's a message at all. Not sure this is the case though, given your statements of having to cycle it so often to make it work again.With Setback enabled, it should pull out of setback when you pick up the iron and use it again instead of Auto OFF so long as this happens > 20min (idle temp kicks in), and < ~1hr (before Auto OFF kicks in). *** Assumes the times weren't changed with a separate device*** (mentioned in the manual; WCB1 or WCB2 IIRC), which I assume you don't have anyway (presume you're the first and only owner, given it's still under warranty).If disabling Setback doesn't solve the problem, I'd say go ahead and open it to check for cracked joints (still thinking intermittent contact issue,ifI understand your meaning of power cycling correctly; i.e. 1x <once> should fix it for setback until it kicks in again if setback is the cause). BTW, the intermittent contacts could be simulating "idle" to the controller, so it goes into Setback and Auto OFF based on the timers. This would also include the iron itself.If you know anyone with a WP80, WSP80, or WMP iron (couple of others listed in the manual), check it with that as it would be the easiest way to find out if this is the culprit. There's a PCB board in the WSP80 or WP80 iron where the cable's individual wires are soldered to, and there could be a bad joint there. See the exploded diagram for the station (has one of the iron as well). If the iron proves to be bad at the connector end, contact Weller for a replacement.If you need, I can take a pic of a disassembled WSP to show the board/how it goes together, but it's not hard to get apart at all (will suffice for the WP80 as well).Past any of this (power unit), send it in IMHO, as it's still covered by warranty.Just in case you've misplaced your manual (or just too inconvenient to locate like mine <buried in a box in the bottom of a closet>),here's a .pdf link for it.

author: Arp
author_rank: Unknown
timestamp: May 12, 2014, 04:08:19 pm
content: Noticed a part in the manual in regard to the setback functionQuoteReckon the power dissipation is so small that it never registers? Tip is a little less than a millimetre. Probably going to turn this feature off all together. Should solve the problem