Denon PMA480R protection circuit

ashok · 10th February 2007, 01:19 PM

Does anyone have the circuit diagram for the protection circuit of the Denon 480R amplifier.
My amp remains in standby mode after power up even though the power amp output section ( speaker out ) does not have dc on it .
Once while trying to trouble shoot , rectified itself and worked OK for some time. But now it refuses to do that again.

Must be a cold solder (?). A circuit diagram would be helpful.
Resoldering all solder points around the area did not help.
Thanks.
Ashok.

XEAGLEKEEPER · 10th February 2007, 11:43 PM

A lot of these protect circuits incorporate DC offset at output detection, and power supply abnormality detection.Check for cold solder connections around the power supply also. I have found that using a non-metallic probe to rake over the PC board handy to help locate faulty connections.The relay maybe sticking also. Give the relay a couple taps.

10th February 2007, 01:19 PM	#1
ashok diyAudio Member Join Date: Jun 2002 Location: 3RS	Denon PMA480R protection circuit Does anyone have the circuit diagram for the protection circuit of the Denon 480R amplifier. My amp remains in standby mode after power up even though the power amp output section ( speaker out ) does not have dc on it . Once while trying to trouble shoot , rectified itself and worked OK for some time. But now it refuses to do that again. Must be a cold solder (?). A circuit diagram would be helpful. Resoldering all solder points around the area did not help. Thanks. Ashok. __________________ AM

10th February 2007, 11:43 PM	#2
XEAGLEKEEPER diyAudio Member Join Date: Jan 2006 Location: central Iowa	A lot of these protect circuits incorporate DC offset at output detection, and power supply abnormality detection.Check for cold solder connections around the power supply also. I have found that using a non-metallic probe to rake over the PC board handy to help locate faulty connections.The relay maybe sticking also. Give the relay a couple taps. __________________ Ret. USAF... AKA- Avionic * Solder slinger for hire...*

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