Cary Audio CAD-280SA V12R

oldhvymec, I see this post is 5 years old however reading through it my tech needs a schematic and Cary Audio is not providing to him. Do you happen to still have a copy you can forward to me, thank you hope you get this message!

Hello. My 1/2amp fb fuse blows instantly on my Right side. Everything smells and looks clean under the hood. Is there anything I should be looking for specifically that would lead to this current issue? Everything is stock/original.

Hello. My 1/2amp fb fuse blows instantly on my Right side. Everything smells and looks clean under the hood. Is there anything I should be looking for specifically that would lead to this current issue? Everything is stock/original.

@jngrausr is yours the 100-120v or 220-240v version V12R?

My former V12R was the 120v version, and ended up finding out the manual was later updated and I moved from a 4v to 5 volt SLOW BLOW. Found out why though, there was a bad hexfred diode from a former upgrade, had to be found and replaced. There can be a cause if it keep blowing fuses.  1) is an EL34 output tube going bad, 2) is the power transformer and/or rectifier going bad?

BEFORE replacing the fuse and just trying again randomly, it's best to troubleshoot in steps.  

Try this procedure carefully:

1. Remove all tubes, insert a correct new fuse, and power up.

   • If the fuse does not blow, the power transformer and rectifier are likely fine.

   • If it does blow, the issue is in the power transformer or primary circuit.

2. Reinstall rectifier and driver tubes only — test again.

3. Add output tubes one at a time while monitoring fuse and bias current

Best NOT to power back up quickly after each test.Apparently if the main power caps are not discharged a little and you power it back up fast after a test, that alone  can blow a fuse. Take your time with each step above. The next owner who acquired my V12R had to replace the main (large) power transformer after playing the amp super hard for many hours on some large demanding electrostatic speakers.  Best to go through the checks, or find a tech to help if not sure.  Good Luck.  

Hello. Thank you so much for the guidance and encouragement. It is the U.S. 100-120v. I see that you have provided a great deal of info on this amp over the years. I will peruse. 

Will report back if I dont electrocute myself.