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Old 8th December 2011, 12:31 AM   #1
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Default Majestic Quantum 1000watts

Is there a schematic reasonably close to this amp. It is in protect mode and finding it tough to figure out.

TL494
1) 4.172
2) 2.317
3) .535
4) 2.363
5) .792
6) .989
7) 0
8) 1.224
9) 0
10) 0
11) 1.224
12) 1.224
13) 2.4
14) 2.4
15) 1.715
16) 2.399
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Old 8th December 2011, 02:02 AM   #2
ultra is offline ultra  Greece
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You need to find out why pin 4 has 2.36V

This is the reason that the pwm goes to protect.
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Old 8th December 2011, 02:42 AM   #3
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This supply has multiple problems. The 5v supply (pin 14) isn't at 5v. It could be that pin 14 is being dragged down or the 5v regulator in the IC has failed.

If you pull pin 14 from the circuit to check voltage on it, you have to also pull pin 13 and connect them together before you apply power.
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Old 8th December 2011, 02:49 AM   #4
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With 13 and 14 pulled and shorted together I get .3V on them.

VCC on pin 12 is low as well, that could be the reason for the +5 reading.
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Old 8th December 2011, 02:50 AM   #5
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If the IC has 12v on pin 12, the IC is defective.
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Old 8th December 2011, 03:12 AM   #6
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Pin 12 is the VCC pin, does that not supply power for the ref?
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Old 8th December 2011, 03:36 AM   #7
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Pin 12 is the power supply input pin for the logic circuits inside the IC (including the 5v reg).
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Old 8th December 2011, 01:50 PM   #8
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Is there a circuit like this in the DVD you sell. All the schematics I have use the LM339 for the power supply shutdown circuitry. I just ordered the DVD this morning.
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Old 8th December 2011, 05:13 PM   #9
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Check your email.
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Old 8th December 2011, 06:03 PM   #10
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Got it, I will compare the two later today.

I was thinking of using my smaller bench supply to source power to pin 12 and see if the 494 starts running. This would possibly show me if the 5V ref is functional.
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