Time for another "Good Idea, Bad Idea" - Page 1
Forum section: electronics / general

author: kolbep
author_rank: Frequent Contributor
timestamp: March 12, 2014, 07:56:06 pm
content: Situation : Washing Machines drain motor packed upUrgency : There are NO clean clothes, and 2 messy children.My Good Idea : Connect an 80W Energy saving lightbulb to the Drain motor, to tell when during the cycle I must drop the drain pipe lower than the machine (for gravity drain), and when the bulb is off, I must raise the pipe so it doesn't drain.My Bad Idea : Not thinking that the manufacturer did not put a relay, or a beefy Triac to run the drain motor.Samsungs Bad Idea : Brake Motor for the Inner Drum is connected to Drain pump motor.The Result : Light at the right times, got washing done fairly quickly,but then in the last 7 minutes, the power driver for the Brake and Drain pumps goes O/C.This causes the brake not to release.This causes the agitator to twist up the clothesThis causes the drum to wobble like crazyThis trips the Uneven Load SwitchThis causes me to bypass the Uneven Load Switch.The Twisted clothes cause the agitator to jamThis causes the Main motor to Jam and overheat (But the motor is still fine after cooling down).This causes me to have to decide :Change the Drain Motor & Remove the Rubberised Gel on the controller, and replace the faulty part. (note : not re-enterable gel)orGet a new (for me) but pre-loved (for somebody else) machine at the Pawn Brokers.Well, that is my Good Idea, Bad Idea for the night.Oh Yes, I just hooked the Brake motor circuit up to a steady supply, just so that I could do the last 7 minute spin cycle, and get the clothes dry enough for the tumble dryer (But I forgot to put the agitator back in, so I had socks etc, jamming between the Inner and Outer Drums at the bracket.Pics or it didn't happen, well here you go :

author: kolbep
author_rank: Frequent Contributor
timestamp: March 12, 2014, 08:00:24 pm
content: Quote from: kolbep on March 12, 2014, 07:56:06 pmNo, I did not put the children in the washing machine, if that was what you were thinking.Wait, Now I am thinking, if I get another machine, I now have an Idea what to do with the old one :-/

author: SeanB
author_rank: Super Contributor
timestamp: March 13, 2014, 07:41:07 pm
content: Want another main board....... I have the baby cousin of that LG washer. Otherwise it is a standard TRIAC driven by the micro.Pump is around R200 from LG direct. Don't ask how I know that price, just that I am looking at one right now. 63096 is the part you are looking for.

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 13, 2014, 08:08:24 pm
content: I'm surprised the triac for the drain pump couldn't handle a light bulb. Motors have a high inrush current.

author: kolbep
author_rank: Frequent Contributor
timestamp: March 13, 2014, 08:46:08 pm
content: What I found strange is that whatever failed has gone o/c.In my experience triacs normallh die s/c.Once I figure out how tomget the rubber off around that section, maybe I will be able to see better.Sean, this is a Samsung washer, and I see you were referring to an lg?

author: kolbep
author_rank: Frequent Contributor
timestamp: March 14, 2014, 06:46:06 pm
content: Success!!!New Triac - Check!New Pump Motor - Check!Machine Put together (with no leftover parts) - Check!Happy Wife - Check!P

author: Smokey
author_rank: Super Contributor
timestamp: March 15, 2014, 12:18:22 am
content: Quote from: kolbep on March 14, 2014, 06:46:06 pmyou should have put that list in order of importance...1) Happy Wife (for now).....2) Other stuffGood job though. I know I always find fixing major appliances really satisfying.

author: SL4P
author_rank: Super Contributor
timestamp: March 15, 2014, 12:42:28 am
content: But the kids are sad... no more cubby washer.Teach them not to climb in the repaired unit !!Great story, well told.

author: nuhamind2
author_rank: Regular Contributor
timestamp: March 15, 2014, 04:13:10 am
content: Is that LG washer, the main board is very similar to mine. By the way, does someone know how the washer know the weight of clothes inside. Since there are no load sensor or anything so my guess is the mainboard monitor the current feed to the motor or by detecting the back EMF

author: kolbep
author_rank: Frequent Contributor
timestamp: March 15, 2014, 04:52:09 am
content: Hi Nuhamind.In response to your question, let me quote Yurgey from armageddon movie:"American Components, Russian Components, all made in Taiwan."The washer is a samsung, but if I understood SeanB, it is similar to the LG. So they most probably use the same parts, just brand it differently.I think monitoring the back emf will be problematic. I cannot see it being too reliable, and can also blow tbe adc monitoring it, just due to the spike.I have not looked at that part of the board, but my guess is tthatwhen they pulse the motor during the load measurement, that they must be measuring the load through a shunt of some kind.I will try to look at it when I open the control panel again to replace the stupid plastic rod for the powerswitch that just decided to malign and snap....

author: Rerouter
author_rank: Super Contributor
timestamp: March 15, 2014, 05:02:06 am
content: most have some kind of anti shake sensor to tell when they are way over loaded, so it could be it pulses the motor one way, measures it, pulses the other-way, measures it, and by knowing its own weight roughly tells how much its been loaded,

author: SeanB
author_rank: Super Contributor
timestamp: March 15, 2014, 05:48:47 am
content: The sensing is done by pulsing the main motor and then measuring via an optoisolator the voltage it generates while spinning down. Small load, short time, large load long run down. It does about 5 cycles then gets the average. This is used during spinning as well to detect the moisture left in the clothes. You hear it spin down a little near the end of the cycle then recover a few times.Samsung, LG same unit just different model number and slightly different front panels. Made in the same factory and from the same moulds. Common parts like motors, drives and pumps and valving. Different inner drum designs and pulsators. No real differences as well between the 7 and 13kg units either motor wise and pump wise. There is also an option ( never seen here) for a pump less unit that has a drain valve. Shake sensor is very simple, if the lid vibrates enough to flap it triggers the lid open reed switch and this then does the rebalance cycle of fill, pulse, drain and start spinning again. More than 3 retries and it gives up and just does the Beep-Boop until you turn it off and manually rebalance.

author: nuhamind2
author_rank: Regular Contributor
timestamp: March 15, 2014, 11:20:51 am
content: A few month ago my washing machine goes beep boop everytime I turn it on. When i fixing it (more like poking everywhere until it work, I still don't know what wrong actually), I really appreciate KISS. The controller is simpler than I tought, If I tasked to design a washing machine with that capability I might end up using load sensor and vibration sensor.QuoteDo you know how similar a washing machine from one manufacture to the other ?, I bought a universal washing machine controller and it's compatible with my washing machine. And becaue it's universal controller it's must be compatible with other washing machine. Probably the difference is on simple trivial thing like the LCD/LED indicator.QuoteDo you know common spec for these part ?, It seem the main component (motor and valve) is off the self component ?QuoteSo the limitation is artificially created ?, even if it is not the difference might just the power rating of the TRIAC. Why upgrading washing mahine is not popular then

author: nuhamind2
author_rank: Regular Contributor
timestamp: March 15, 2014, 11:27:13 am
content: Oh and other thing. I crack open the capacitive water level sensor. I thought the capacitor is custom molded or something, in fact it use two off the self mylar capacitor with the same capacitance and the measuring circuit is classic pierce oscillator (with hex inverter logic chip).It seem that there are not much innovation in consumer electronic, except for making the cheaper.

author: SeanB
author_rank: Super Contributor
timestamp: March 15, 2014, 12:35:51 pm
content: WWW.tecsa.co.zahas the parts catalog online for the washing machines. You will see just how much the parts are either common or universal for many machines.Horrors are older Defy Automaid mechanical switch assemblies, they come with a 2 page installation sheet with them. Changing them is a challenge with all the cables you have to attach.