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Overload detection circuit for UPC1237
Overload detection circuit for UPC1237
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Old 10th January 2015, 11:22 PM   #21
andrewlebon is offline andrewlebon  India
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Hello Andreas
greetings could you post correct schematic if possible
warm regards
Andrew
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Old 11th January 2015, 12:50 AM   #22
andrewlebon is offline andrewlebon  India
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Default upc1237 short circuit overload

مدار محافظ امپلي فاير کامل (محافظ DC , تاخير , اتصال کوتاه و...)
Maybe this is useful
warm regards
Andrew
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File Type: jpg 20080107200023A.jpg (46.0 KB, 651 views)
File Type: jpg 20100313191716O.jpg (79.9 KB, 635 views)
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Old 11th January 2015, 02:06 AM   #23
andrewlebon is offline andrewlebon  India
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Default upc1237 short circuit overload

schematic of UPC1237 pcb and files on link
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File Type: jpg dg.jpg (276.1 KB, 638 views)
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Old 11th January 2015, 06:42 AM   #24
Andreas AVM is offline Andreas AVM  Ukraine
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Three schemes that you have shown - it is more appropriate to correct circuit.
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Old 11th January 2015, 06:50 AM   #25
kunalagon is offline kunalagon
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Default How does this works, anyway?

Hello,
I am wondering if I am wrong but those schematic, and all those overcurrent protectors would work OFF/ON/OFF/ON/OFF... infinitly while amp output terminal are shorted and output ac signal is high enough to make voltage drop on Re resistor to make sesning transistor conducting?
When load is connected to amp output voltage on Re wont get high enough to make sensing transistor conducting and relay on upc1237 wont broke off. When output is shorted (or small impedance connected) and output ac signal is high enough, relay of upc1237 will broke off, and disconnect shorted output line, and Re voltage would become small enough to make relay broke off again, and the proces would be OFF/ON/OFF/ON/OFF/ON...

Am I right ?
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Old 11th January 2015, 06:57 AM   #26
Andreas AVM is offline Andreas AVM  Ukraine
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Three schemes that you have shown - it is more appropriate to correct circuit.
I have recently restored an old amplifier Sansui BA150. Protection scheme
created his own without the use of the chip. I like that better.
Attached Images
File Type: gif PR S BA150.GIF (73.2 KB, 622 views)
File Type: gif PR S BA150 2.GIF (50.6 KB, 591 views)
File Type: jpg S BA 150 01.jpg (358.7 KB, 432 views)
File Type: jpg S BA 150 02.jpg (274.7 KB, 285 views)
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Old 11th January 2015, 09:21 AM   #27
kunalagon is offline kunalagon
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Andreas, is this your own protection or Sansui own? Sansui was using BC transistors?
Anyway, I am not sure how is this circuit works but it looks like it needs 0.7V+0.7V+0.7V for VT4 to make it conductive, so 2.1V. And the logic is the same, right? It needs to feel voltage drops to make relay broke off?
I am trying to say this:
1. Output load connected-relay on
2. Output shored - relay off (when relay off, voltage drops down and relay on, when relay on, voltage drops rise and relay off, etc, etc... so it is repetitive on/off/on/off?)

Here is also protection schematic of Denon PMA-2000 implemented via thyristor:
Attached Images
File Type: png 1.png (163.7 KB, 339 views)
File Type: png 2.png (197.9 KB, 288 views)
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Old 11th January 2015, 01:33 PM   #28
Andreas AVM is offline Andreas AVM  Ukraine
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Quote:
Originally Posted by kunalagon View Post
Hello,
I am wondering if I am wrong but those schematic, and all those overcurrent protectors would work OFF/ON/OFF/ON/OFF... infinitly while amp output terminal are shorted and output ac signal is high enough to make voltage drop on Re resistor to make sesning transistor conducting?
When load is connected to amp output voltage on Re wont get high enough to make sensing transistor conducting and relay on upc1237 wont broke off. When output is shorted (or small impedance connected) and output ac signal is high enough, relay of upc1237 will broke off, and disconnect shorted output line, and Re voltage would become small enough to make relay broke off again, and the proces would be OFF/ON/OFF/ON/OFF/ON...

Am I right ?
Greetings Kunalagon.
Yes, that's right, the time interval is off delay time when the amplifier.
It's ugly, but it will give the user know that there is a fault or short circuit. There is also the trigger and protection schemes - after a trip switch is only possible after the power amplifier.
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Old 11th January 2015, 01:47 PM   #29
kunalagon is offline kunalagon
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Thank you Andreas. That is all I need to know. And I see upc1237 have latching function, so it is possible to use it by connecting capacitor between pin 3 and gnd, and then IC needs power off to reset relay
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Old 11th January 2015, 02:04 PM   #30
Andreas AVM is offline Andreas AVM  Ukraine
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Quote:
Originally Posted by kunalagon View Post
Andreas, is this your own protection or Sansui own? Sansui was using BC transistors?
Yes, this is my own design of the amplifier. In Sansui BA150 primitive circuit protection, fuse ... and DC sensor that is triggered thyristors output circuit.
Scheme for Sansui VA150 I could not find, so using a circuit end portion Sansui AU999 - they are identical.
Quote:
Anyway, I am not sure how is this circuit works but it looks like it needs 0.7V+0.7V+0.7V for VT4 to make it conductive, so 2.1V. And the logic is the same, right? It needs to feel voltage drops to make relay broke off?
No, not true, the circuit is triggered when output short circuit when the voltage across the resistor emitter of the output transistor reaches 0.7V.
When there is no output short circuit, the threshold increase - operates a chain of R3 D1. Together with the R2 forms a divider.
Quote:
I am trying to say this:
1. Output load connected-relay on
2. Output shored - relay off (when relay off, voltage drops down and relay on, when relay on, voltage drops rise and relay off, etc, etc... so it is repetitive on/off/on/off?)

Here is also protection schematic of Denon PMA-2000 implemented via thyristor:
Yes, that's right,
1 - in short circuit mode amplifier does not spoil, but the user will know the fault load and must be eliminated.
2 - if the input signal is so high or low the user to connect the load - the amplifier will also be cyclically switched off. If you make less volume - again amplifier will work as usual.
But Denon have to turn off / on, it's uncomfortable.
In my circuit is very simple to build latch mode and it will work as Denon.
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