Help determining resistor and a diode values(picture attached) - Page 1
Forum section: electronics / beginners

author: Dalek84
author_rank: Newbie
timestamp: November 05, 2013, 10:43:24 pm
content: Hello,I need help determining values on resistors and a diode (picture attached)The resistors (labeled R30 and R31 in the attached picture) I know are 470 ohms, but I am not sure what wattage. What would be the easiest way to determine this? Also, as the resistors have gotten hot enough to burn away their coating, I cannot tell if the final color band is gold or silver. What would be an easy way to determine this?The diode (labeled D16 in the attached picture) is marked "1N47 46A 933". I am having trouble locating this particular diode online.Any help would be appreciated for this keen electrical amateur!Thanks

author: ElectricGuy
author_rank: Regular Contributor
timestamp: November 05, 2013, 11:43:26 pm
content: Quote from: Dalek84 on November 05, 2013, 10:43:24 pmHi;1N4746A its a 18V Zener. The resistors looks like 1W or 1/2W.

author: kxenos
author_rank: Frequent Contributor
timestamp: November 06, 2013, 12:04:49 am
content: If you're going to replace the resistors and diode, it would be nice to lift them just half a centimeter off the board just to avoid heating. The yellow marks you see is from heat. Also, if the diode is burnt, you can install somewhat bigger wattage diode.

author: hanndoddi
author_rank: Contributor
timestamp: November 06, 2013, 12:11:27 am
content: I found this on yahoo1/8 watt carbon resistors are about 3/8" long x 1/16" diam.1/4 watt carbons are about 3/8" long x 1/8" diam1/2 watt carbons are about 1/2" long x 1/4" diam1 watt carbons are about 3/4" long x 1/4 " diam2 watt carbons are about 11/16" long x 5/16" diamhttp://answers.yahoo.com/question/index?qid=20080129191043AA91Wzt

author: Kryoclasm
author_rank: Regular Contributor
timestamp: November 06, 2013, 12:12:11 am
content: Is that a washer machine control board?

author: trackman44
author_rank: Regular Contributor
timestamp: November 06, 2013, 01:01:45 am
content: Do you have the basics for repairing electronic circuits? (i.e soldering iron, pair of pliers, multimeter). If so, pull out one of each of the leads on the resistors and measure the resistance. They look like 470 Ohm 5% 1/2 Watt resistors. If they measure within tolerance ( between 446.5 - 493.5 Ohms) resolder their leads back to the board. By the looks of the picture nothing seems out of the ordinary ( other than the heat marks on the PCB). It's possible that D16 could be shorted or open and the only way to find out is to check it with a meter.Will

author: Dalek84
author_rank: Newbie
timestamp: November 06, 2013, 01:07:34 am
content: It is actually a control unit out of a really nice dishwasher that a friend gave me. I figured there was nothing to lose in experimenting.Thanks for the advice. I do have everything I need, I dabble from time to time, but unfortunately only enough to ensure that I stay an amateur.I have not had the opportunity to check the resistors just yet. I am familiar with checking them. What is the best way to check the diode with a multimeter?

author: Dalek84
author_rank: Newbie
timestamp: November 06, 2013, 01:42:59 am
content: http://www.amazon.com/pcs-1N4746A-1N4746-Zener-Diode/dp/B00DWU6SPQ/ref=sr_1_1?ie=UTF8&qid=1383696326&sr=8-1&keywords=1n4746a+DiodeWould this diode be an adequate replacement for the one on the board? The specs appear to be same, but it looks different. The one on the board is labeled "1N47 46A 933".

author: c4757p
author_rank: Super Contributor
timestamp: November 06, 2013, 01:51:16 am
content: It's fine. That's just a generic picture of the DO-41 package, which is more commonly plastic.

author: Dalek84
author_rank: Newbie
timestamp: November 06, 2013, 01:55:42 am
content: Ok Thanks,The one that is on the board has a metallic cover, and this one is plastic, so I just wanted to be sure. Thanks for the help.

author: c4757p
author_rank: Super Contributor
timestamp: November 06, 2013, 01:56:49 am
content: Oh, I didn't even notice the picture...I assumed it was a glass DO-41 like many Zeners. That's not even "metallic", it's just painted in inverse.Er... I think. On a second look, maybe it is?Doesn't matter though, it's close enough.

author: Dalek84
author_rank: Newbie
timestamp: November 06, 2013, 02:05:17 am
content: Here is a closeup. How would I go about checking this with a multimeter?

author: c4757p
author_rank: Super Contributor
timestamp: November 06, 2013, 02:11:50 am
content: Lift the cathode (the end with the stripe) off the board, then test like this. You should read about 17-19V.

author: SeanB
author_rank: Super Contributor
timestamp: November 06, 2013, 07:36:57 pm
content: Those resistors are actually 1W fusible resistors. They either measure the right resistance or will be open circuit. As they have been getting rather warm I would suggest replacing with 2W units, providing there is enough height above the board to accomodate a resistor that will be 3 times the diameter. Check the diode as mentioned above, or simply use the diode test function on most DVM's to see if it conducts one way and not the other, which means it most likely works and is not open circuit or shorted. While you are at it replace the 2.7 uF capacitor with an identical value and voltage film unit, it will most likely be low in value.

author: Dalek84
author_rank: Newbie
timestamp: November 06, 2013, 10:33:35 pm
content: I actually picked up some new 470 ohm1/2 watt resistors today and they are the same size as the ones on the board. Are these not the correct ones? What is the difference in a fusible and regular resistor, and how would I go about finding them?

author: Dalek84
author_rank: Newbie
timestamp: November 06, 2013, 10:46:29 pm
content: Also, would this be an adequate replacement for the capacitor you were talking about?http://www.digikey.com/product-detail/en/ECQ-E2275KF/EF2275-ND/56507

author: SeanB
author_rank: Super Contributor
timestamp: November 07, 2013, 07:30:01 pm
content: It will work for a short time, but is not the right capacitor for this application, you need a class X capacitor rated for connection across the mains.http://www.epcos.com/inf/20/20/db/fc_2009/X2_B32921_926.pdfIs the type you want.http://www.digikey.com/product-search/en?pv13=116&pv5=10136&pv5=10140&pv5=10137&FV=fff40002%2Cfff80010&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25