Dumb Luck?

[nevetslab]

AuntieM dropped off a Mesa Lonstar Combo amp with No Reverb working. Though the way it was worded, it also seemed to infer the Amp itself was also not working. Verified it was, so that hopefully led to just repairing the reverb tank.

Got the tank extracted from their better execution of reverb pouch mounting (Velcro strap across the nice pouch, remove single screw holding that down, and extracting the pouch from the floor of the cabinet). Both the input and output DCR measured nominal, indicating a working tank. Points to the drive or return circuits of the chassis, so I thought. Uggghh. Heavy and hard-to-extract chassis from the cabinet, then having to attach wings to the chassis to support it on my lab jacks.

While removing the reverb cables from the chassis, I discovered only one had to be unplugged. The WHT unshielded wire (return wire?) didn't appear to be plugged in. Cable tie just below the cable clamp screwed into the side of the cabinet had that section of cable to the amp chassis VERY TIGHT. Was that UNPLUGGED? I cut the tie, allowing the cable form from the cable clamp on up to the chassis to loosen, and firmly seated that connector. Powered the amp back up, and......I'll be Buggered. GOT REVERB!

Had I NOT found that wire seemingly NOT plugged in, I would have gone thru the aggravating motions of pulling the chassis out, digging thru the circuits to find nothing wrong. Would have let me bill the client for more labor hours, if I chose NOT to cut him some slack for not finding the problem right off, but sure saved me the grief of working on a Mesa amp. Not my favorite repair task. Heavy sucker to lift at my age.

[The Dude]

That is precisely why I check the IN/OUT DCR at the amp side first- cables and all. If you have good DCR there, there's usually no need to even remove the tank. If you don't have the correct DCR, then you remove the tank to see if it's cables or tank. It often saves extra work. In this case you'd have found the problem without even removing the tank. Of course, you could still have broken tank springs, but that's usually obvious via the noise they make rolling around.

[nevetslab]

That is precisely why I check the IN/OUT DCR at the amp side first- cables and all. If you have good DCR there, there's usually no need to even remove the tank. If you don't have the correct DCR, then you remove the tank to see if it's cables or tank. It often saves extra work. In this case you'd have found the problem without even removing the tank.

Normally, when it's a Fender Twin or Deluxe, I do just that. Today, my mind wasn't thinking so clearly, and figuring it WAS a broken wire in the tank, I extracted the tank to find the no problem with the tank. However, I MIGHT NOT have found or noticed that connection wasn't seated at the corner of the amp chassis. I know I would NOT have been good humor had I removed the chassis to find no problem with the amp. Ah, well......at least I didn't have to pull a Mesa Lonestar apart.

[The Dude]

......Today, my mind wasn't thinking so clearly......

Understandable after a dark, powerless, sweltering, sleepless, hot night in the dark!