Help identifying a burnt resistor WB27X10438

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Discussion Overview

The discussion revolves around identifying a burnt resistor from a microwave PCB (part number WB27X10438). Participants share their experiences and challenges in determining the resistor's value, considering its potential role in the circuit, and discussing possible causes for its failure.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Jason seeks help identifying a burnt resistor and shares links to similar boards with burn marks.
  • Some participants suggest the resistor may be a low ohm inrush current limiter, potentially in series with the bridge.
  • There is confusion regarding how to read the color bands on a 5-band resistor, with participants discussing methods to decode them.
  • Dave questions the assumption that the resistor is faulty, suggesting it may still function despite its appearance and encourages testing with a multimeter.
  • Jason reports a multimeter reading of approximately 30.1k ohms, raising questions about the resistor's standard value.
  • Participants discuss the possibility of the resistor being a fuse or a symptom of a deeper issue in the circuit.
  • There are differing interpretations of the resistor's color bands, with some suggesting it could be a 28.9k ohm resistor based on visual analysis.
  • One participant provides links to resources for decoding resistor values and emphasizes the importance of understanding the circuit connections.

Areas of Agreement / Disagreement

Participants express uncertainty about the resistor's value and functionality, with multiple competing views on its identification and role in the circuit. The discussion remains unresolved regarding the exact nature of the resistor and the cause of its failure.

Contextual Notes

Limitations include the difficulty in accurately identifying the resistor's color bands due to damage and photographic conditions. There is also a lack of consensus on the resistor's standard value and its implications for circuit functionality.

  • #31
jcy110 said:
I just fixed my GE Microwave XL 1800 for $2.95. I purchased the 1/4W, 30k Ohm resistor and a 220uf 50V capacitor. Soldered them in, put the WB27X10438 control
board back into the unit and it works perfectly. The large black power relay is not manufactured anymore so I figured I would replace the capacitor and resistor, if that didn't work I would have to spring 150-160 for a new power control board.

View attachment 189655

View attachment 189656

jcy110, I believe I have the same problem as you with the WB27X10438 board. What caused you to replace the 220uf 50V capacitor in addition to the resistor? All thread I've read (on this site and others) indicate the resistor as a source of the problem, but not the capacitor. thanks
 
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  • #32
Sgib, as you can see in my pics on page 1, the cap is starting to bulge, that is why I replaced it. For a total of like 3.00 its worth the work.
 
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