Replacement DP3T slide switch - Page 1
Forum section: electronics / repair

author: Ranayna
author_rank: Super Contributor
timestamp: December 05, 2018, 08:22:46 pm
content: Hi everyone,I am looking for a somewhat specific replacement part for a bicycle lamp (labeled "LUMOTEC IQ Cyo T") that has intermittent function. After disassembling the thing I identified the slide switch as the most likely culprit. It is (was) a very cheap looking slide switch, already rusty, and I was not able to desolder without destroying itso I will need a replacement anywayAfter quite some searching I found one switch that would fit mechanically:https://www.digikey.de/product-detail/de/te-connectivity-alcoswitch-switches/1825163-2/450-1618-ND/1202239Datasheet:https://www.te.com/commerce/DocumentDelivery/DDEController?Action=srchrtrv&DocNm=1825163&DocType=Customer+Drawing&DocLang=EnglishBut that switch is shorting, and I am quite sure that the existing one is non shorting...Also it seems to be somewhat on the expensive side, but I really do not know what those switches reasonably costAm I missing something, or are switches really that specific?Parameters of the existing switch, mechanical:Length: 16mmWitdh: 6mmHeight: 5.5mmLength of the "nub": 5mmHeight of the "nub": about 4mmSliding path of the "nub": 10mm (the "nub" parameters are important since the switch is actuated indirectly)Pin spacing in both directions: about 2.5mm, I assume 0.1 inchThe metal part of the switch has the letters "KD" stamped in, but otherwise no markingsNo mounting holes are available on the pcbElectrical: Voltage and current rating unknown, but the light itself is fed by 6 voltsTwo neighboring pins are connected in each switch position, with two separated poles. ON-ON-ON was the term that found me the switch I linked above.I'm not a switch guy, so I hope I am not mixing up the terminology.A replacement for the whole light was quoted to me at about 100 euro () so i hope I will find a proper switch with your helpEDIT: Wrong forum... Now wasn't there a way to move topics ourselves?EDIT2: Found it, the move function, that is

author: ArthurDent
author_rank: Super Contributor
timestamp: December 05, 2018, 09:14:12 pm
content: I'm not sure if you're describing the switch correctly. I 'think' what you may want is a 2-pole 3-position switch so you might have an off, low beam, and high beam light output. You may want to check eBay because switches there are fairly cheap and some are good quality. I don't know how your switch is mounted but you can get switches with or without panel mounting tabs.I don't even know if this is what you need, you'd have to check the listings out carefully, but this is an example of a switch made for panel mount.https://www.ebay.com/itm/5-Pcs-x-5mm-High-Knob-8-Pin-3-Position-2P3T-DP3T-Panel-Slide-Switch-0-5A-50V-DC/310569757685

author: Ranayna
author_rank: Super Contributor
timestamp: December 05, 2018, 09:38:38 pm
content: The diagram for the switch you linked does not match what i see after the switch broke, and what i measured before...What I see now with the switch apart are two rows of four contacts. In the plastic moving part there where two copper sliding contacts, both in the middle, and just wide enough to bridge 2 of those contacts.So, with the switch to the left, the first two pins had contact, with the switch in the middle, the middle pins had contact, and with the switch to the right, the right pins had contact.But anyway, yes, i mixed up poles and throws in the title...

author: Nusa
author_rank: Super Contributor
timestamp: December 05, 2018, 10:43:39 pm
content: Actually, I think you got it right the first time. What you describe sounds like what they call DP3T in slide switches.To answer your original question, stock switch specifications are typically either make-before-break (MBB) or break-before-make (BBM). There are valid reasons for wanting either specification. If the original was BBM, you probably don't want to change that.See if any markings on the original switch are visible. Identifying the original manufacturer could go a long way to finding the exact replacement. Another thought is to contact the light manufacturer support people and ask about either a buying a replacement switch or a part number for it. Sometimes it's just that easy.

author: johnkenyon
author_rank: Regular Contributor
timestamp: December 06, 2018, 12:49:17 pm
content: Quote from: Nusa on December 05, 2018, 10:43:39 pmIf the switch is being used in a "low-off-high" application then it doesn't matter if the switch is MBB because there will only be a simultaneous make with the "off" terminals which won't be connected to anything anyway.

author: Ranayna
author_rank: Super Contributor
timestamp: December 07, 2018, 12:05:54 pm
content: So, I attached croc clips to the first and third pin of one of the poles, connected to a multimeter with fast continuity.I then manually slowly moved the copper slider along the contacts. At no point there was even the suggestion of a beep, so if I am not completely mistaken, this confirms that the original switch is BBM, aka. non-shorting.The light is MCU controlled, I think, but I did not have the time yet to check if the switch itself is in the current path of the LEDs...

author: Ranayna
author_rank: Super Contributor
timestamp: December 12, 2018, 09:49:35 pm
content: Well, since after a lot of searching I did not find another switch with the same layout than the one I linked, I bought a couple of those.Figuring it could not break anymoreThe replacement switch looksexactlylike the broken one, except that it does not have that stamped "KD". I measured it, and indeed the switch-positions measured the same. I also did the same test, attaching a lead to PIN 1 and PIN 3 of the same pole to a DMM in continuity, that I tried to to with the remains of the broken one, and got the same result: no beep. So I figured there is something wrong with that test and went ahead replacing the switch.After having trouble with a clogged ZD-915, I finally managed to replace the switch, and success, the lamp works again as it should!At least one small project that i actually finished