Help with transistor switch  - Page 1
Forum section: electronics / beginners

author: zorthgo
author_rank: Regular Contributor
timestamp: February 24, 2013, 08:10:51 pm
content: Hi Guys,I have a problem with my washing machine that I believe I can fix with a little switch device that my teacher introduced to us during embedded system design. The problem is that I can't remember what that switch was. This is the scenario I have right now. For some reason, the inlet valve is not getting 120v that it requires. It is getting only 5v. Even though 5V is not enough power to run the inlet valve, it is enough to trigger a switch that would activate an external source of 120v to run the valve. So, can anyone tell me what chip I need that I can plug the 120V to one pin, have the 5V connect to the other pin to activate the switch, and the machine to the third pin (so it can receive the 120V).Thanks!

author: Marco
author_rank: Super Contributor
timestamp: February 24, 2013, 08:51:39 pm
content: I wouldn't go messing around with those voltages in a machine with lots of vibrations, water and which is already clearly broken and getting ready to break even more in the near future. Lets say you put the right switch in there (depends on if it's AC or DC BTW) and suddenly the voltage goes back to 120V, what happens then?

author: PA0PBZ
author_rank: Super Contributor
timestamp: February 24, 2013, 09:03:16 pm
content: You should fix the problem.You really should fix the problem.Fix it, don't screw with it.Anyway, I think what you are trying to remember is a solid state relay.

author: Unknown
author_rank: Unknown
timestamp: February 24, 2013, 09:42:46 pm
content: Most modern dishwashers and washing machines are fitted with what's called an "aqua-stop" device; it's purpose is to stop the water inlet if either the pipe is leaking or the polystyrene float switch under the machine is triggered from a leak. You really need to isolate and fix the actual problem because circumventing an anti-leak system is a really really bad idea!

author: zorthgo
author_rank: Regular Contributor
timestamp: February 24, 2013, 09:52:17 pm
content: Thanks guys for the help!I guess I will have to bite the bullet and call a repair person (ouch to my pride and wallet. lol!). I don't suppose there are repair manuals for washing machines. Are there?Thanks!

author: ignator
author_rank: Regular Contributor
timestamp: February 24, 2013, 10:30:52 pm
content: Quote from: zorthgo on February 24, 2013, 09:52:17 pmThe hardest part of working on a wash machine is figuring out how to open it. Maytags (one of many USA brands) has neet hidden catches you use a putty knife to open, and then the top swings open on a rear hinge. Every wash machine I've ever fixed has a wiring diagram hidden inside by the main control unit. You should be able to read this, and figure out where the wire for the water valve is sourced, then see if it's part of a drum switch or more modern electronic board. You did not indicate how old y0ur machine is. But all mechanical units are still sold today, as well as all electronic controlled machines.Don't give up too easy, you really can't hurt anything pulling a few screws out to see what's inside, unless they hid these, and you have to use a BFH and chisel to open.ignator

author: ddavidebor
author_rank: Super Contributor
timestamp: February 24, 2013, 10:59:19 pm
content: You can use triac and optotriac for switch 120v with 5v

author: Paul Moir
author_rank: Frequent Contributor
timestamp: February 25, 2013, 12:14:52 am
content: You need the services of an appliance repair forum, such as:http://appliantology.org/It's almost always better to fix the problem rather than implement a work-around.EDIT: wrong link.

author: SeanB
author_rank: Super Contributor
timestamp: February 25, 2013, 03:43:47 pm
content: What make and model. Eserviceinfo.com has a lot of the manuals there for download ( though some of them are multipart RAR archives) and some have very interesting watermarks on them.

author: Unknown
author_rank: Unknown
timestamp: March 02, 2013, 10:12:14 am
content: I have a Haynes Dishwasher Manual, but they do one for washing machines as well; which would certainly be worth a read! I wouldn't give any money to the repair man without checking over all the switches and solenoids etc first.

author: zorthgo
author_rank: Regular Contributor
timestamp: March 02, 2013, 04:38:59 pm
content: Thanks guys for all the advice! This week was CRAZY being mid-term week and all. Didn't have a second to breath! But answering ignator's question, my machine is a GE GSWF100R10BB and it is about 1.5 years. So, I am assuming that it is electronically controlled. Thanks Paul for the link, I am going to hit that forum also and see if I can fix this thing. I am pumped! %-B