Mesa Blue Angel burned board

[Gtr_tech]

I had onna these come in with the complaint of instantly blowing fuses even after replacing all output tubes. After doing the requisite resistance checks looking for shorts or low R paths to gnd, I noticed a "funny" looking area of the board under 2 diodes and a 100r resistor. Sure enough....after pulling these components the board has a pretty burned section there. One diode was leaky, so that explains the fuse pops. But.....I was thinking of just "flying" these parts off the board with leads to take that burned part out of the path. I haven't pulled the board to see what is under the burned section....and I'm avoiding this if I can to keep cost down (huge PITA to remove the board) as long as there's no traces on the other side of the board that need repair.

Anyone been thru this situation before and will it work ok to fly in these parts?

[Gtr_tech]

Went ahead and yanked the board out enough to see the damaged area just to satisfy my own curiosity. No burn damage on the underside, so looks like we're ok to proceed as planned.

Just FYI, there is a trace running under that area of the board. So if you have one that is burned real bad, you need to grind out the carbonized board and jumper the trace from the underside.

[Leo_Gnardo]

SGM used to rail on endlessly about just this sort of thing, as if every Mesa was doomed & fixing it was a daily event.

I've encountered it rarely & in brands other than Mesa too.

Now it's your turn.

As long as you grind away the burnt bits of board you should be OK flying the new parts over the void. I wouldn't trust any board bits that are black with char or toasted dark brown. Get out the Dremel & vacuum, goggles & earplugs.

[Gtr_tech]

Oh yea, the carbon gets shitcanned. There will still be plate winding voltage in that area so you don't want any conductive paths from there to the filter caps thats fer sher.

[Gtr_tech]

Just an update on this. It ended up coming together just fine. After the carbon was ground away (verified by shining a flashlight thru the board from the underside), the diodes and resistor were added off the board straight from the recto tube socket to the first filter cap. Burned it in for an hour or so....happy as a clam.

Just a heads up for anyone else encountering this issue.