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short caps of electrolytics fault goes

looxuser

Dec 28, 2015
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I have an audio device with two caps around an ic amp JRC2073. I replaced these two caps and the no audio fault remained, however by chance i shorted the exposed caps of these two with a finger each on one hand and got audio. My hand resistance was about 0.4mohn so i tried large resistor across instead and got audio to, why is this please? all the solder joints look and test good.
 

Delta Prime

Jul 29, 2020
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You should remember cuz you are dealing with audio AC not DC the resistance measurements you have made on biological tissue is incorrect. You have a capacitance the human body has a capacitance of approximately 200 picofarad in conjunction with the skin resistance we are now in the realm of capacitive reactance XC and inductive reactance XL. skin resistance is now an impedance Z. Therefore...
In the case of biological tissue
photo_1684173616227.png
And in your words by chance

i shorted the exposed caps of these two with a finger each on one hand and got audio
You could have easily been thrown across the room and knocked unconscious or even worse! I have personally seen it happen in the workplace. depending on the values in the DC working voltage of the capacitors.
 

looxuser

Dec 28, 2015
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You should remember cuz you are dealing with audio AC not DC the resistance measurements you have made on biological tissue is incorrect. You have a capacitance the human body has a capacitance of approximately 200 picofarad in conjunction with the skin resistance we are now in the realm of capacitive reactance XC and inductive reactance XL. skin resistance is now an impedance Z. Therefore...
In the case of biological tissue
View attachment 59051
And in your words by chance


You could have easily been thrown across the room and knocked unconscious or even worse! I have personally seen it happen in the workplace. depending on the values in the DC working voltage of the capacitors.
thanks its only 12volts
 

Delta Prime

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thanks its only 12volts
You're most certainly welcome.
That's how it begins."It's only 12 volts"
I like LEDs you like LEDs? My LEDs are the 5 mm, little ones. Just for kicks and giggles I'm going to put a resistor in series to limit the current.The maximum current to LED is 20 milliamps but I wanted to last longer so I want 10 milliamps.
Anything higher than 10 milliamps or
Any current greater than 10 milliamps can freeze or paralyze your muscles.
If you touch that wire or try to grab it you might not be able let go. You might even hold on to that wire even tighter and you won't be able to let go at all. And eventually (one or two minutes) respiratory paralysis will kick in. which means you will stop breathing.I am not trying to scare you. I am telling you how it is. Be safe.
 

Bluejets

Oct 5, 2014
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Any current greater than 10 milliamps can freeze or paralyze your muscles.
If you touch that wire or try to grab it you might not be able let go. You might even hold on to that wire even tighter and you won't be able to let go at all. And eventually (one or two minutes) respiratory paralysis will kick in. which means you will stop breathing.I am not trying to scare you. I am telling you how it is. Be safe.
Think you need to visit a theory doctor real quick.
Load of hogwash.
 

Bluejets

Oct 5, 2014
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I have an audio device with two caps around an ic amp JRC2073. I replaced these two caps and the no audio fault remained, however by chance i shorted the exposed caps of these two with a finger each on one hand and got audio. My hand resistance was about 0.4mohn so i tried large resistor across instead and got audio to, why is this please? all the solder joints look and test good.
Best hang off until one of the audio specialists give you some solid reliable advice.
 

Delta Prime

Jul 29, 2020
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Think you need to visit a theory doctor real quick.
Load of hogwash
You sound like my father.
Tisk tisk. Having a bad day?
I'll take OSHA with me.
Oink! oink!
Occupational Safety and Health Administration, U.S. Department of Labor
Screenshot_20230515_165354.jpg
 

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Delta Prime

Jul 29, 2020
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I have an audio device with two caps around an ic amp JRC2073. I replaced these two caps and the no audio fault remained
Apologies I was suffering a massive brain fart.
Valid nonetheless
So if I'm reading this correctly you still have no audio output from jrc 2073 that is the fault correct?
If so...would you happen to have a schematic or the unit it came out of and your replacement capacitors we'll need the datasheet on those as well. If you have an oscilloscope I would check if you have a good input. The beginning is the best place to start.
Also how many speakers are you driving would you happen to know the configuration.
Screenshot_20230515_180834.jpg
 

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looxuser

Dec 28, 2015
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You sound like my father.
Tisk tisk. Having a bad day?
I'll take OSHA with me.
Oink! oink!
Occupational Safety and Health Administration, U.S. Department of Labor
View attachment 59054
Its right of course to flag electrical danager, I did find this on Google

What is a dangerous voltage?​

It's actually the current that is important rather than the voltage, but due to the resistance of the body you can't get a dangerous current without there being sufficiently high voltage. You can work this out yourself using ohms law, but the important thing as far as this is concerned is to remember the safety principles. Generally you are relatively safe dealing with voltages of less than 50V, but anything above that can be dangerous.

You are generally safe from electrocution on most electronic circuits that run off domestic batteries, including 12v car batteries. There may however be batteries in your home that can pose a real danger, such as the output from a UPS (uninterruptible power supply) for a computer, or if you have a home energy system such as solar panels.

Even if you equipment is designed to run at less than the dangerous voltage for electrocution it may still pose a risk of burns, fire or even explosion - so keep reading.
 

looxuser

Dec 28, 2015
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Apologies I was suffering a massive brain fart.
Valid nonetheless
So if I'm reading this correctly you still have no audio output from jrc 2073 that is the fault correct?
If so...would you happen to have a schematic or the unit it came out of and your replacement capacitors we'll need the datasheet on those as well. If you have an oscilloscope I would check if you have a good input. The beginning is the best place to start.
Also how many speakers are you driving would you happen to know the configuration.
View attachment 59056
Thanks theres no schematic but I was able to draw the attached. Orange signifies the two electrolytic caps I shorted the exposed tops with hand and then soldered in a 1M resistor. The device now outputs sound, there is no longer any volume control but if I increase the resistor from 1M to 2.4M the volume gets lounder, distorted and loud if just a short there instead of resistor. The caps C5 100uF 50v and C2 4.7uf 50v, they are just ebay generic.

amp section.JPG
 

Delta Prime

Jul 29, 2020
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Is there any way you could take a couple photos? is this on a breadboard?
Thank you for the schematic but more information is needed for me I am not an audio specialist anymore. When I was 16 years old perhaps.
 

Delta Prime

Jul 29, 2020
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Also would you happen to have an oscilloscope or at least a digital multimeter I can walk you through the process of troubleshooting .we will be taking those resistors out of there or anything else you add it on.
 

looxuser

Dec 28, 2015
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Also would you happen to have an oscilloscope or at least a digital multimeter I can walk you through the process of troubleshooting .we will be taking those resistors out of there or anything else you add it on.
Wow that would be very very much appreciated Delta Prime, yes I have scope, meters everything really and yes that resistor is only lightly in so can come out no problem. Photos shortly
 

Delta Prime

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Any and all information please.
Link?
Manufacturer name?
Development board ?
Breakout board?
Bluetooth ?
USB power supply?
Possibility of photos both sides PCB?
 

looxuser

Dec 28, 2015
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Bluejets

Oct 5, 2014
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What is a dangerous voltage?https://www.safeworkaustralia.gov.a...ging-electrical-risks_in_the_workplace-v3.pdf

It's actually the current that is important rather than the voltage, but due to the resistance of the body you can't get a dangerous current without there being sufficiently high voltage. You can work this out yourself using ohms law, but the important thing as far as this is concerned is to remember the safety principles. Generally you are relatively safe dealing with voltages of less than 50V, but anything above that can be dangerous.

You are generally safe from electrocution on most electronic circuits that run off domestic batteries, including 12v car batteries. There may however be batteries in your home that can pose a real danger, such as the output from a UPS (uninterruptible power supply) for a computer, or if you have a home energy system such as solar panels.

Even if you equipment is designed to run at less than the dangerous voltage for electrocution it may still pose a risk of burns, fire or even explosion - so keep reading.


Voltage Extra low voltage means voltage that does not exceed 50 volts alternating current (50 V a.c.) or 120 volts ripple-free direct current (120 V ripple-free d.c.). Low voltage means voltage that exceeds extra-low voltage and does not exceed 1000 volts alternating current (1000 V a.c.) or 1500 volts direct current (1500 V d.c.). High voltage means voltage that exceeds low voltage.

Reference.............. https://www.safeworkaustralia.gov.a...ging-electrical-risks_in_the_workplace-v3.pdf
 
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