Yamaha R-500 Power Supply Schematic

[scootsity5]

Hello all

I'm having a hard time tracking down a high enough resolution picture of the power supply section of the schematic for an R-500.

I switched it on a few weeks ago, smelled some magic smoke and the system stopped working. I noticed that it powers on, all lights come on, but it never puts out sound. I also notice that I never hear the click from the relay closing. I'm assuming the issue is one of the electrolytics (hence the smoke) in the relay delay citcuit. I'm just having a hard time reading the text in the schematic for those caps. Anyone have a picture of that area of the schematic? The ones in the library and at hfe aren't very readable in that area.

Thanks!

 

[clinic-audio]

Hello

Check first if you have any DC offset on relay contacts from output of the amplifier

 

[scootsity5]

Do you mean see if the relay is closing by measuring resistance from the relay to the output? Or, do you mean check the DC offset of the output? I'm confused as to why there'd be a DC offset between the output and the relay. I know roughly where on the board the pop was, I just need to see that corner of the schematic.

 

[avionic]

Do you mean see if the relay is closing by measuring resistance from the relay to the output?

No..... Need to check for DC voltage at the amplifiers output before it gets to the relay contacts. The protect circuit might be working as designed.

 

[avionic]

I'm confused as to why there'd be a DC offset between the output and the relay.

If one or both of the outputs are shorted there will be massive DC at the relay contacts. The protect circuit would sense that DC and stop the relay from "setting".

 

[avionic]

I am assuming this unit has STK2040 outputs.

Just verified..It does.

 

[avionic]

Check the DC voltage using the service manuals procedure's test points for adjusting DC offset. That is a good place before the relay contacts.

 

[scootsity5]

OK, I understand what you're saying now. Thanks. I'll give it a look this week.

 

[scootsity5]

The past few weeks have been insane at work. I'll get to this when I can. Thanks for the help and the patience.