Troubleshooting Sunn Amp

[Carl]

 My Sunn Solos 2 is dead. It just Quit at a gig with a slight burnt odor. The power appears to not come however if the power on switch is bypassed the circuit breaker violently and immediately pops out and a slight burn odor is present. There is nothing visible and I cannot tell for sure where the burn is coming from. I have worked on tube amps abd can read schematics etc but this solid state stuff is another world to me.
 Any sugguestions would be appreciated.
 
 Thanks in advance.
 Carl

[Don T.]

Hello:
 Well I'm not the Solos expert but the symptoms sound like one of three things.
1. the rectifier is shorted (blows fuse fast and rarely leaves a visible sign.
2. output transistors shorted (same as above)
3. filter cap shorted. (has distictive odor and can sometimes see burn marks or bubbling up of outer covering)

Only these type of high current faults can cause a fast breaker or fuse and not cause severe scorching of components.
Don T.

[Carl]

 Thanks Im checking those tonite. I'll post back

[Carl]

 Nope . I guess its over for this one. New Bridge Rect to replace bad one, New electrolytic caps throughout since the ones in it were over 20 yrs old. I dont know, no shorted trans etc. It just dont work. Oh well it had a good life and the 15" Speaker is worth more than I paid for the amp so Ill try not to mourn too deeply.

[Don T.]

Hello:
 It's not black magic, you now know some things that weren't wrong (to quote T.A. Edison).
Don T.

[HG Thor]

Don is right. There has to be a short in the highest power circuit somewhere. The switch is fried so that indicates it may be somewhere in the 120AC line voltage side of the power supply. One other possibility is the power transformer is shorted. Try lifting the outputs of the power xformer section by section to see if a lower voltage supply is loading it. If it still blows the breaker when the outputs of the power xformer are isolated, them the problem lies in it or back through the AC supply circuit that feeds the xformer.

If these tests allow you power up, then you next find the path that is loading the circuit.

[Anonymous]

a tip for finding high power end short I have used on solid state (won't work well on tube as voltages are all out and filament current screw up method) put a light buld,100 watt ok, in series with amp. Bulb will glow full brightness with short but not blow fuses. Then start troubleshooting by removing loads or testing voltages.