Hakko 936  - Page 1
Forum section: electronics / repair

author: Cameron Kover
author_rank: Contributor
timestamp: March 12, 2015, 08:36:47 pm
content: The iron heats up, but the temperature doesn't adjust. The LED just stays on no matter what the temperature is set at, doesn't blink just stays on. Could one of the IC gone bad? Or could the calibration just be out? The Tip really gets oxidation really bad, like the temperature is staying at the highest, Thanks.

author: lowimpedance
author_rank: Super Contributor
timestamp: March 12, 2015, 10:43:07 pm
content: Sounds like the temp sensor in the hand piece is faulty (maybe!!). Should be plenty of info including schematic if you search around.So here is an excellent fault finding exercise. Is it the base station or the hand piece or the connector between the two or a break in the cable etc ?.Do you know anyone else with the same unit that you could try your hand piece on so as to eliminate that as the cause?.At any rate you will probably have to hunt down parts on ebay, either clones or real.

author: Cameron Kover
author_rank: Contributor
timestamp: March 12, 2015, 11:02:08 pm
content: I have another hand piece and it does the same, when I turn the station on (Without the iron plugged in) the LED still comes on? Isn't the led supposed to be off when the iron is unplugged?

author: lowimpedance
author_rank: Super Contributor
timestamp: March 12, 2015, 11:16:00 pm
content: Ah ha step 1 complete, looks like the station is the problem.Trying a different hand piece eliminated the original one and the connector as the possible culprits.The LED does go off if the hand piece is unplugged.Also the LED goes off above the set point, and then cycles on and off around the set point.next step, get the circuit.Do you have a DMM ?. Hopefully yes, so check Q1 for short cct.(make sure its unplugged from the mains before opening the case!)

author: Cameron Kover
author_rank: Contributor
timestamp: March 13, 2015, 12:16:08 am
content: Doesn't show any resistance between collector and emitter?

author: lowimpedance
author_rank: Super Contributor
timestamp: March 13, 2015, 12:42:22 am
content: Q1 is a triac, see this PDF for info on a quick operational test for example .www.ab.com/support/abdrives/documentation/fb/1012.pdfCould be the upc1701 triac controller is toast, check ebay for those. (cheapest source)Do you have access to another iron ? since its likely you will need it to repair the Hakko !.

author: Cameron Kover
author_rank: Contributor
timestamp: March 13, 2015, 12:48:41 am
content: Yea the 1701C gets really hot.

author: BravoV
author_rank: Super Contributor
timestamp: March 13, 2015, 01:49:21 am
content: Assuming you're using a genuine Hakko 936, have you check the heater & sensor resistance ?Below pic is posted from this threadHERE

author: lowimpedance
author_rank: Super Contributor
timestamp: March 13, 2015, 02:00:14 am
content: He did try another hand piece with the same result ,unless both are faulty!.But since the LED stayed on without the iron plugged in which its not supposed to do then its a good bet the station is the fault.Still its not a bad idea to check anyway for peace of mind.All assumptions are its not a clone!.

author: BravoV
author_rank: Super Contributor
timestamp: March 13, 2015, 02:02:09 am
content: I missed that, yeah, its the station.