Author Topic: resistor over cappacitors  (Read 1155 times)

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Offline spdf

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resistor over cappacitors
« on: July 20, 2017, 11:06:53 am »
Hello guys, recently I've disassembled old faulty amp and I found on one side a small value resistor acros caps. What is the purpose of this resistor? Is it originally from manufacturer or it was repaired somehow?

I have attached a photo of a board.
 

Online Rerouter

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Re: resistor over cappacitors
« Reply #1 on: July 20, 2017, 11:24:37 am »
without knowing where it sits in the circuit its hard to say, however the solder colour is the same as the surrounding components, meaning its likely a factory bodge component,

up to the early 00's it was somewhat common to see bodge components, where they span there first batch, found under testing or heard back from the early adopters that there was something not quite right, and rather than paying new tooling for a board respin they just added a note for the assemblers to fit that component there.

 

Offline Gyro

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Re: resistor over cappacitors
« Reply #2 on: July 20, 2017, 03:25:49 pm »
The end of the orange wire is broken.
Chris

"Victor Meldrew, the Crimson Avenger!"
 

Offline TransistorMan

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Re: resistor over cappacitors
« Reply #3 on: July 20, 2017, 10:25:03 pm »
What is exact value of resistor?

If that capacitor is used for supply voltage filtering, then it's most likely bleeder resistor, and its purpose is to discharge capacitor after amplifier is turned off.

If it's bleeder resistor, it's value should be something like 220-1000 ohms (just my approximation)
 

Offline cncjerry

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Re: resistor over cappacitors
« Reply #4 on: July 21, 2017, 03:49:04 am »
I can't tell from the picture, but in cases where you stacked capacitors to hit a higher voltage, you used a resistive divider network to keep the voltage across each capacitor the same (balanced).  For instance, if you had 120v you wanted to filter with three, 40V capacitors, you would put three 10k resistors (or a lower value) across each cap in series.  This isn't used that often except in much higher voltage supplies.  Lower voltage supplies used a resistor as a bleeder to drain down the capacitors when the power is turned off.

Jerry
 

Offline spdf

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Re: resistor over cappacitors
« Reply #5 on: July 21, 2017, 08:24:52 am »
yo guys, I found it in the schematics :)
 


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