Author Topic: Help Identifying 0805 Resistor Value  (Read 411 times)

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Offline AstutePauciloquentTopic starter

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Help Identifying 0805 Resistor Value
« on: December 03, 2024, 10:49:26 pm »
Hello Everyone, I have been diagnosing this 600Watt PSU. After removing 2 blown Mosfets, I also discovered some blown resistors, and some other resistors that have had their value changed. Such as the two lower 103 in this pic, they should have a resistance value of 10K Ohms but they only read 110 Ohms. I'm confident in Identifying and replacing the faulty 0805 resistors with the values written on them, but what are these resistors that I have drawn a red box around? They all measure as 100 Ohms, but there are others with different values around the board, and seeing that some of these resistors have had there value changed, I can't really trust there measured resistance.

This is such a great resource full of highly knowledgeable people, and it is an honer to be part of this community, thank you in advance.

« Last Edit: December 03, 2024, 10:53:24 pm by AstutePauciloquent »
 

Offline coromonadalix

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Re: Help Identifying 0805 Resistor Value
« Reply #1 on: December 04, 2024, 02:11:07 am »
i would have said diodes,  try testing them in diode mode both ways
 

Offline AstutePauciloquentTopic starter

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Re: Help Identifying 0805 Resistor Value
« Reply #2 on: December 04, 2024, 02:40:05 am »
i would have said diodes,  try testing them in diode mode both ways

Tested them in diode mode, both ways they do not behave like diodes
 

Offline Whales

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Re: Help Identifying 0805 Resistor Value
« Reply #3 on: December 04, 2024, 04:01:50 am »
i would have said diodes,  try testing them in diode mode both ways

Tested them in diode mode, both ways they do not behave like diodes

It's in parallel with a 100ohm or 1k-ohm resistor (marking "1000") next to it.  You will need to remove the diode from the circuit to measure it properly.

Offline AstutePauciloquentTopic starter

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Re: Help Identifying 0805 Resistor Value
« Reply #4 on: December 04, 2024, 07:21:16 am »
i would have said diodes,  try testing them in diode mode both ways

Tested them in diode mode, both ways they do not behave like diodes

It's in parallel with a 100ohm or 1k-ohm resistor (marking "1000") next to it.  You will need to remove the diode from the circuit to measure it properly.

Yes I see thanks, they are indeed diodes!
 
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Offline pcprogrammer

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Re: Help Identifying 0805 Resistor Value
« Reply #5 on: December 04, 2024, 07:35:57 am »
I also discovered some blown resistors, and some other resistors that have had their value changed. Such as the two lower 103 in this pic, they should have a resistance value of 10K Ohms but they only read 110 Ohms.

If you measure components in circuit the values depend on what the rest of the circuit is. Just like with the diodes you have to take the components out to get an accurate reading.

Online fzabkar

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Re: Help Identifying 0805 Resistor Value
« Reply #6 on: December 04, 2024, 08:13:58 am »
... some other resistors that have had their value changed. Such as the two lower 103 in this pic, they should have a resistance value of 10K Ohms but they only read 110 Ohms.

When resistors fail, they usually increase their resistance or go open circuit. It would be very unlikely for the resistance to be lowered. Instead, there must be a low resistance path in parallel with these 10K resistors.
 


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