I have a Yamaha A-960 with no output. Testing revealed that the power supply rail voltages are less than half of what they should be, measuring 20V.
This has some weird power supply design I don't understand.
There is a photocoupler. Maybe that is the issue but I'm not sure. There is a voltage check in the service manual, I'm supposed to get 1.2V across a test point and I'm getting half that.
What should I check, and what is even going on here? Schematic is on hifiengine, but here's a clipping.
This has some weird power supply design I don't understand.
There is a photocoupler. Maybe that is the issue but I'm not sure. There is a voltage check in the service manual, I'm supposed to get 1.2V across a test point and I'm getting half that.
What should I check, and what is even going on here? Schematic is on hifiengine, but here's a clipping.
Attachments
That's a Bob Carver designed power supply. "mag coil" type. Check with the Carver gurus on thecarversite.com for information on how to deal with it.
On the chance that it's something simple, I note there's a number of different versions intended for markets--- see page 10 of the service manual. There's a "General model" that appears to have a 120/240 VAC selection.
Can you explore these issues and determine which version you have? Perhaps you are powering a 240VAC model with 120VAC?
Can you explore these issues and determine which version you have? Perhaps you are powering a 240VAC model with 120VAC?