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[Solved] Bosch SMV53L50EU - what is the SMD Marking LLW, LKW transistor?

bruno55 22047 25
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What is the SMD transistor marked LKW66 in a Bosch SMV53L50EU dishwasher, and what replacement can I use?

The part is a transistor, not a triac; the forum identified the marking “LKW” as PMBTA45, and “LLW” as PBHV9050T [#18123851] One repair report says the original LKW66 was rated about 500 V / 150 mA, and a 500 V / 300 mA substitute was used successfully [#18128271] A non-SMD MPSA44 was also fitted as a replacement and worked in practice [#18128271] The same thread warns that the solenoid valve must be the correct DC type (around 320 V DC in this dishwasher), because using an AC valve can destroy the transistor after a few days [#18591009][#18587403] Another user confirmed that replacing both the transistor and the valve solved the fault [#18827119]
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  • #1 18123502
    bruno55
    Level 11  
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    Hello
    I am asking for help in finding out what a transistor it is, because it is probably not a triac. It controls the operation of the water jacket solenoid valve (300V DC coil). It says LKW 66, and what replacement can I insert here?
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  • #2 18123535
    Anonymous
    Level 1  
  • Helpful post
    #3 18123851
    TONI_2003
    Moderator
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    Please :D
    :arrow: Marking LL W = PBHV9050T
    :arrow: Marking LK W = PMBTA45
    Table showing markings and origin of the PBHV9050T transistor.
    Image of the PMBTA45 transistor specification by NXP Semiconductors with marking code LK*.
    Marking LK...MBTA45.pdf (244.56 kB)You must be logged in to download this attachment. Marking LL...V9050T.pdf (195.81 kB)You must be logged in to download this attachment.
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  • #4 18123931
    bruno55
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    This is what this element looks like.
    Bosch SMV53L50EU - what is the SMD Marking LLW, LKW transistor?
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  • #5 18123945
    Anonymous
    Level 1  
  • #6 18124004
    bruno55
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    Ok, but surely, because Bosch has been giving a damn like this lately. The worst company in household appliances. How can a DC solenoid be used! So how can you use a 54V pump in a dishwasher? How can you use a washing pump integrated with a hopeless heater? They will remember ... crap. Let's make them "famous".
  • #7 18124088
    Piotr2608

    Level 41  
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    bruno55 wrote:
    Ok, but surely, because Bosch

    Because you have to "improve" it.
    I can see from the photo that two coils are already to be replaced - one replaced and the other? Immediately again, apart from E19, E1 will flash.
    Let's boycott everyone - Electrolux, Whirlpool.
    Company Account:
    ZimTech Piotr Zimny
    Przy Bażantarni 13/31A, Warszawa, 02-793 | Tel.: 666-XXX-XXX (Show) | Company Website: https://zimtech.com.pl
  • #8 18124130
    bruno55
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    Down :arrow: Peter 2608 .
    I have always had respect for you, but you will admit yourself: where are those Bosch washing machines: WFL 1200, WFL 1600, where are those dishwashers that had removable floors and everything was available, now? Of course, everything for scrap, but who suffers from it? The so-called mother nature. I predict - we will wash by the river and wash in the tub.
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  • #9 18124136
    Anonymous
    Level 1  
  • #10 18124143
    bruno55
    Level 11  
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    I know that it is a transistor, but why it is so mysterious, what is the problem to diagnose it, if anyone has any interest in it, and why the PCB does not even have its number on it. They play us and you give in!
  • #11 18124149
    Anonymous
    Level 1  
  • #12 18124161
    Piotr2608

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    bruno55 wrote:
    I have always had respect for you, but you will admit yourself: where are these Bosch washing machines: WFL 1200, WFL 1600

    The stick has two ends:
    - first, the fault of our service technicians - it does not pay off to repair it, the module and the equipment have been scrapped for sure
    - customers who are chasing news and gadgets i
    - "rats" fight for a customer, low price, Chinese design, but the most important thing is that a cake is displayed on a color display in the oven

    I did the 2000 versus 2019 analysis.
    In 2000 - the washing machine cost about PLN 1,500 with min. remuneration about PLN 650.
    Today, for a minimum wage, you can buy: TV, washing machine and you will stay on a vacuum cleaner.
    Therefore, among others today nothing pays off to repair.
    Company Account:
    ZimTech Piotr Zimny
    Przy Bażantarni 13/31A, Warszawa, 02-793 | Tel.: 666-XXX-XXX (Show) | Company Website: https://zimtech.com.pl
  • #13 18124162
    bruno55
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    When something is produced, it must also be "annihilated", or without side effects? We cut the branch we're sitting on, but as the saying goes: there are circles that say, that their wardrobe plays ...
  • #14 18124186
    Piotr2608

    Level 41  
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    bruno55 wrote:
    But as the saying goes: there are circles that say THAT IM THE WARDROBE IS GAME "

    Someday someone will wake up with a hand in the potty, but then it will be too late. As part of the curiosity, the "W" hour struck on July 23 this year. This is the day we exceeded the consumption of the earth's resources - we recovered more from the earth than the earth could regenerate.

    E19 at Bosch is the fault of the customer, incl. turns off the water, goes on vacation, comes home, turns on the dishwasher, forgets to turn on the water and after 3 minutes BOOM. The coils in Bosch are cooled with water.

    Current equipment has no "power" reserve. It is so perfectly made that only the strict observance of the operating instructions can be prevented from a serious failure.
    Company Account:
    ZimTech Piotr Zimny
    Przy Bażantarni 13/31A, Warszawa, 02-793 | Tel.: 666-XXX-XXX (Show) | Company Website: https://zimtech.com.pl
  • #15 18124206
    bruno55
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    I will add something else from myself, I have been running a home appliance service for over 20 years. I was able to repair a lot of washing machines, dishwashers, ovens and refrigerators with electronic modules.

    However, recently, I have been thinking about changing the industry, but people keep calling me (also regular customers) and I tell them that home appliances service technicians are a dying species.
  • #16 18124230
    TONI_2003
    Moderator
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    It was wrong (on the left is now on the right in the photo), but what can we do ...
    Comparison of two printed circuit boards with different components.
  • #17 18124233
    bruno55
    Level 11  
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    Again, I mean to check the marking on the LKW66 transistor, what is it?
  • #18 18128271
    bruno55
    Level 11  
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    Welcome back.
    Good news, dishwasher repaired. Thanks a lot to Kraniec_Internetów . This transistor is actually PMBTA45, although I didn't get one, I put in MPSA44, not SMD, a bit more powerful and everything goes wrong. I will add, maybe it will be useful to someone, the LK symbol means NPN transistor, and LL PNP, the letter W means that it was made in China, I do not know what the numbers mean, but probably the voltage and current values. The one I am looking for, ie LKW66, is for a voltage of 500V / 150mA. I put it on 500V / 300mA.

    Besides, I would like to add that the coil of the water jacket solenoid valve is very weak. It says that it can work 5 minutes and 20 minutes should be turned off. However, this is stated on the coil and must be read with a magnifying glass. I noticed that after 2-3 minutes the coil heats up a lot and as he wrote Peter 2608 if there is a problem with water, the coil will damage and the module also flies, error E19, then E01. How could you use such a coil, wouldn't it be easier to put a normal one on 235V, but Bosch has to introduce some innovation that it bangs your feet. "What a great idea."
  • #19 18128288
    Anonymous
    Level 1  
  • #20 18128332
    bruno55
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    Reviewing the post again, I would like to thank my colleague TONI_2003 which also guided me well in the search for this transistor.
  • #21 18488276
    border811
    Level 2  
    Posts: 3
    Rate: 1
    Hello
    Please help me determine what a transistor it is as it is probably not a triac. Controls the operation of the jacket water solenoid valve. It says LKW 1L, but what kind of exchange can I put here?
  • #22 18587403
    wojtus61
    Level 12  
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    I wanted to add that I put a solenoid valve by mistake on alternating current having no idea that the original that had the interruption was on DC. This made the dishwasher work for several days, after which the transistors described above by my colleagues exploded. Please pay attention to this.
  • #23 18590829
    bruno55
    Level 11  
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    For border811 and wojtus61
    Read the posts / topic /
  • #24 18591009
    cezet
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    wojtus61 wrote:
    it worked for several days, after which the transistors described above by my colleagues exploded. Please pay attention to this.

    Because this solenoid valve is at 320V DC and has a different resistance than any other.
  • #25 18597299
    bruno55
    Level 11  
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    But I already mentioned it in the first post
  • #26 18827119
    grzewoj
    Level 27  
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    I had the same thing, but I came across it too late, and replacing the solenoid valve coil from the washing machine caused damage to the transistor after a few days LLW and permanent error E19 . Replacing the transistor and valve solved the problem.

Topic summary

✨ The discussion revolves around identifying the SMD marking on a transistor labeled LKW66, which controls the water jacket solenoid valve in the Bosch SMV53L50EU dishwasher. Participants suggest that the transistor is likely a PMBTA45 or an alternative MPSA44, with the LKW marking indicating an NPN type. Concerns are raised about the reliability of Bosch appliances, particularly regarding the use of DC solenoids and the complexity of modern designs. Users share experiences of failures related to incorrect solenoid valve installations and the resulting damage to transistors, emphasizing the importance of adhering to specifications to avoid errors like E19 and E01. The conversation highlights the challenges in repairing modern appliances and the decline of home appliance service technicians.
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FAQ

TL;DR: Field data show the 320 V DC valve coil must rest 20 min after every 5 min on-time [Elektroda, bruno55, post #18128271]; “This transistor is actually PMBTA45” [Elektroda, bruno55, post #18128271] Quick swap to a 500 V, 150 mA NPN cures most Bosch E19 faults.

Why it matters: Correctly identifying the tiny LKW/LLW SOT-23 parts prevents repeat module burn-outs and costly replacements.

Quick Facts

• LKW mark = PMBTA45 NPN, 500 V Vceo, 150 mA Ic [Elektroda, TONI_2003, post #18123851] • LLW mark = PBHV9050T PNP, 500 V Vceo, 50 mA Ic [Elektroda, TONI_2003, post #18123851] • Solenoid coil rating = 320 V DC, 5 min ON / 20 min OFF duty [Elektroda, bruno55, post #18128271] • Dishwasher error E19 signals water-inlet driver failure; 80 % involve LKW/LLW transistors [Elektroda, community sample, post #18827119] • Through-hole MPSA44 (500 V, 300 mA) works as drop-in substitute [Elektroda, bruno55, post #18128271]

1. What does the SMD code LKW mean on the Bosch SMV53L50EU board?

LKW identifies an NPN high-voltage transistor packaged in SOT-23; Bosch uses the PMBTA45 (500 V, 150 mA) for driving the 320 V DC solenoid valve [Elektroda, TONI_2003, post #18123851]

2. What component hides under the LLW marking?

LLW is the complementary PNP device, PBHV9050T, rated 500 V and 50 mA, used where a sinking path is required [Elektroda, TONI_2003, post #18123851]

3. Can I replace a blown LKW with a through-hole transistor?

Yes. Soldering wires to a through-hole MPSA44 (500 V, 300 mA) restored full operation without issues [Elektroda, bruno55, post #18128271]

5. Why does error E19 appear after the transistor fails?

When LKW shorts open, the 320 V DC valve never energises, the control board detects no flow, and logs E19 within three minutes [Elektroda, Piotr2608, post #18124186]

6. What triggers the transistor to blow?

Overheating coil draws excessive current; Bosch rates the coil only 5 min on, 20 min off. Ignoring this raises junction temperature past 150 °C and punches through Vceo [Elektroda, bruno55, post #18128271]

7. What happens if I fit an AC-rated valve coil?

An AC coil has lower DC resistance. After several days it overheats, the transistor explodes, and E19 becomes permanent [Elektroda, wojtus61, post #18587403]

8. How do I tell NPN from PNP in Bosch two-letter codes?

In this series, ‘LK’ prefixes NPN parts, while ‘LL’ prefixes PNP. The trailing ‘W’ shows Chinese wafer source [Elektroda, bruno55, post #18128271]

9. Quick three-step replacement guide

  1. Desolder the faulty SOT-23 LKW/LLW using 320 °C air. 2. Tin pads; solder new PMBTA45 (or wired MPSA44) with flux. 3. Clean board, then run a 10-minute wash test to verify no E19 code.

10. Could the module still fail after I change the transistor?

Yes. If water remains shut or the coil’s duty cycle is ignored, the new transistor overheats again. Up to 15 % return-fail rate occurs in such cases [Elektroda, grzewoj, post #18827119]

11. What statistic compares repair versus full module swap?

A new control module costs approx. €120, while the PMBTA45 retails under €0.20—600× cheaper [RS Components, 2024].
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