What is this part and resistor value - Page 1
Forum section: electronics / repair

author: Peter Tryndoch
author_rank: Contributor
timestamp: July 17, 2024, 09:15:12 am
content: What is this component that looks like a diode and is labeled "TRSB1" ?My colour vision is not the best. Is the value of this shunt resistor 4R9?Hopefully the image will get attached to this post Ok.Altronics did not have a 4R9 so I went with a 5R6 5WSome history - if you're interested:This is the low voltage supply for an overly complicated clothes dryer.The shunt resistor failed. I replaced it with the 5R6 and then the control chip let out the magic smoke.I measured the DC resistance of the primary as 0R2.I rewound the transformer and now the primary measures 15R. Much better.Now waiting on delivery of replacement LNK364GN

author: fzabkar
author_rank: Super Contributor
timestamp: July 17, 2024, 03:43:22 pm
content: TRSB1 is a TVS diode (Transorb). The two numbers are wildly different parts, though. :-?http://markingcodes.com/search/c/200ahttp://markingcodes.com/search/c/26aSee the snubber components in this example:https://www.eeweb.com/wp-content/uploads/articles-articles-flyback-transformer-design-1387179412.png

author: Peter Tryndoch
author_rank: Contributor
timestamp: July 18, 2024, 09:01:26 am
content: Somehow I don't think the value of that shunt resistor is 4R9Does anyone want to have a go at reading the colour code?Just blew another shunt, chip and transformer primary.Transformer rerewinding time - fun!Luckily I bought 10 chips. Foresight?What is my luck in getting a schematic?Device: Electrolux clothes dryer EDP2074PDWCircuit board 0194_0003 GBTW Thank you fzabkar for explaining TRSB1

author: PA0PBZ
author_rank: Super Contributor
timestamp: July 18, 2024, 09:45:44 am
content: Unfortunately the service manual does not have schematics but it does have a better picture of the resistor:I'd say it's 47 Ohms.(At least when that's the resistor you are referring too)

author: Peter Tryndoch
author_rank: Contributor
timestamp: July 18, 2024, 10:11:18 am
content: 47R sounds better.The board looks slightly different but the colours seem to match what I have found online.I have attached some more pics of the resistor.

author: bastl_r
author_rank: Regular Contributor
timestamp: July 19, 2024, 10:19:22 pm
content: HiThis is a fuseresistor.Its vaule ist 4R7.Black at the 3th ring is .0

author: Peter Tryndoch
author_rank: Contributor
timestamp: July 20, 2024, 12:02:28 am
content: In my last attempt I used a regular 5R6 shunt resistor (not knowing that it needs to be fusible)I blew the resistor, chip (new replacement) and transformer primary (which was 15R)So I don't know what is left in the primary that could be at fault.Could a failure in the low voltage section cause such a catastrophic failure?The output windings on the transformer measure in the 0R2 range, but this would be typical I would think.Measuring with the transformer removed, on the low voltage side I get readings in the Megohms or open, so no short there.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: July 20, 2024, 12:11:17 am
content: F The last band is white. it is a fusible resistor. Black in this position means wire woundThe other colors are (I Think I can see the Colors)_Yellow = 4Purple = 7Black = 0 MultiplierGold = ToleranceSo47 Ohms FusibleThe original resistor blew because of failure in the circuit. It did it's job.

author: Peter Tryndoch
author_rank: Contributor
timestamp: July 23, 2024, 11:25:02 pm
content: It looks like the primary smoothing capacitor is the culprit.Odd as its capacitance and ESR check out OK.No bulging or leaking.I ran it up on dim bulb and it was passing maximum current.Removed the cap and it went way down.So now I know what to replace.I also want to replace the transient suppressor diode as I don't know how to test if it is good or not,and thought that it would be a good idea.Mouser don't stock it. I have emailed digikey and elemnt14 - waiting for reply.Does anyone know where I can get it?I have attached a fresh pic of it.

author: fzabkar
author_rank: Super Contributor
timestamp: July 23, 2024, 11:39:53 pm
content: It's a Vishay (General Semiconductor) 200V unidirectional TVS diode. Depending on the dimensions, it could be SMAJ200A, SMBJ200A or SMCJ200A.

author: Peter Tryndoch
author_rank: Contributor
timestamp: July 24, 2024, 02:09:17 am
content: Thank you fzabkar.SMAJ200A is what I will go with.I plugged those values in at Mouser and they do have quite a few, just not Vishay.I found one by Yageo which is a good fit.There are bidirectional and unidirectional.Given that the original has a band on it and is in series with a diode.I'll say unidirectional.