Orion 250 HCCA no rail voltage

ECM · 11th March 2010, 07:01 PM

Working on a second generation (Digital Reference) and it will not produce rail voltage.

The amp turns on, doesn't draw excessive current, outputs measure fine in circuit.

The first set of rectifiers after the two rows of PS fets read about +/-22volts.

The main voltage rails going to the outputs do not come up.

Will the protection circuit prevent the rails from coming up?

Thanks,
ECM

Perry Babin · 11th March 2010, 07:48 PM

Did you check for rail voltage on the emitter of the output transistors?

Are you sure you read -22v on one of those rectifiers?

ECM · 12th March 2010, 07:14 AM

Yes, I checked for rail voltage on the output transistors and all read zero.

I'll double check the rectifier voltage again.

If the main rectifiers on the bottom of the board fail by going open, will that prevent the rail voltage from showing up? The red light on the other end of the board was lit as well.

I'll have a look at it again today and take more measurements.

Perry Babin · 12th March 2010, 07:43 AM

Place the black probe on the RCA jack shield. Does that allow the meter to read the rail voltage?

If so, the 120 ohm resistor between primary and secondary ground is open.

11th March 2010, 07:01 PM	#1
ECM diyAudio Member Join Date: Jul 2004 Location: Cyprus	Orion 250 HCCA no rail voltage Working on a second generation (Digital Reference) and it will not produce rail voltage. The amp turns on, doesn't draw excessive current, outputs measure fine in circuit. The first set of rectifiers after the two rows of PS fets read about +/-22volts. The main voltage rails going to the outputs do not come up. Will the protection circuit prevent the rails from coming up? Thanks, ECM

11th March 2010, 07:48 PM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Did you check for rail voltage on the emitter of the output transistors? Are you sure you read -22v on one of those rectifiers? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

12th March 2010, 07:43 AM	#4
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Place the black probe on the RCA jack shield. Does that allow the meter to read the rail voltage? If so, the 120 ohm resistor between primary and secondary ground is open. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

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12th March 2010, 07:14 AM	#3
ECM diyAudio Member Join Date: Jul 2004 Location: Cyprus	Yes, I checked for rail voltage on the output transistors and all read zero. I'll double check the rectifier voltage again. If the main rectifiers on the bottom of the board fail by going open, will that prevent the rail voltage from showing up? The red light on the other end of the board was lit as well. I'll have a look at it again today and take more measurements.

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