Need help fixing my FX-888 - Page 1
Forum section: electronics / general

author: ndmrslp
author_rank: Newbie
timestamp: February 01, 2013, 01:58:54 pm
content: I still can't believe this happened, but I managed to partially cut the cord for the pencil on my FX-888. This happened while the station was on of course. I was able to repair the pencil cord since the cut was only about 10" from the pencil -- it's just a bit shorter now. Unfortunately, I think the incident may have damaged the station itself since I'm getting no heat at all from it now. The heating LED doesn't even turn on. The blue pencil wire was cut completely and the red wire was slightly nicked (no exposed wire, but there may have been a momentary short between them when they were cut).Here is what I have done so far:* performed all the resistance checks for the pencil and pencil cord as listed in the user manual - all ok* checked fuse inside base - ok* looked around the inside of the base and saw nothing obviously fried* realized that I can't remove anything to test it because I can't desolder nowCan anyone point me toward the best approach to troubleshooting this or maybe just some likely suspect parts to check? It would be much appreciated since I'mreallynot looking forward to paying to have it repaired

author: Unknown
author_rank: Unknown
timestamp: February 01, 2013, 02:54:33 pm
content: Assuming you have re-wired the iron correctly, with it's thermal sensing wires in the right place, to the multi pin Din-Plug or it's iron PCB ?... then it's possible the input temperature stage has been damaged !. Without a circuit to understand the station design, it will be very difficult.A look around the Web might find a circuit of this station, you might get lucky; otherwise give Hakko an E-Mail URL:http://www.hakko.com/Here is their contact page:https://www.hakko.com/english/contact/inquiry_form.htmlThey might help you out, since the damage was caused by a miss-judgement of sight event.

author: ndmrslp
author_rank: Newbie
timestamp: February 01, 2013, 08:29:56 pm
content: Quote from: vlf3 on February 01, 2013, 02:54:33 pmYes, that's my fear. I brought the pencil in to work to have it soldered, so I had two sets of eyes on the connections, and I'm as sure as I can be that they are correct. Also, all the cord & pencil resistance tests from the manual check out ok.Quote from: vlf3 on February 01, 2013, 02:54:33 pmSounds like my best bet at this point. Thanks!Quote from: vlf3 on February 01, 2013, 02:54:33 pmWow, how did you know that's how it happened? My vision isn't so good up close anymore so I usually take my glasses off for close work. For some reason I didn't this time and while using a wire stripper to cut a jumper, the stripping jaws caught the pencil cord

author: amyk
author_rank: Super Contributor
timestamp: February 02, 2013, 12:40:39 pm
content: The genuine 888 uses a proprietary ASIC to drive the LED and triac (see Dave's hack video). If 24VAC got into the sensor input it would probably kill the IC.This might be one of those instances where a 936 or any other all-analog clone would've been much easier to repair since the worse that would happen is a blown LM324/358 (although unlikely since they can take 32V at their inputs.)

author: Unknown
author_rank: Unknown
timestamp: February 02, 2013, 02:02:51 pm
content: @ ndmrslp...QuoteI have the reverse of your sight problem, age related and very frustrating thus, I guessed where you were coming from; my commiserations.