What amp problems have you had?

  • Thread starter Thread starter dstroud
  • Start date Start date
I was cleaning up my Bassman RI last night, to take and trade towards something new. I was checking the bias, and it looked a little cold, right at/under 50%. It's a fixed bias setup (you have to change a resistor to change the bias, pre-LTD RI) so I tried another set of tubes. These put it right in spec for the plate voltage, right between 50-60% dissipation. I turned the amp to standby to power down, and I saw a flash on the board. I turn it back on, and sure enough, I have no bias current. A quick poke around with the meter revealed a blown grid/screen resistor. So I replaced both (just in case) and put the old tubes back in, let it burn in for a good hour before powering down. Turned it on and played it for a while this morning, and all was good again. I don't know if the other tubes just pulled too much current (which seems odd at 50-60% plate diss.) or if the resistor was just weak and I got lucky that it pooped the bed at home, and not while they were checking it out as a trade-in. :doh:
 
Had tubes blow up on my VHT UL, Mesa Coli and Mesa recto head. When the tubes blew on the recto, it wiped out a screen resistor too. *!* Easy fix but screwed me at the gig pretty good. When the UL blew tubes at the gig, I figured out which pair were bad, ran the other pair and just had to swap out fuses. Not a big deal.

Had the standby switch cable come loose from a Randall RM100 head, Had a part blow in a Mesa .50 EL84 head that left a dime sized HOLE in the PCB.

That's about it. If you gig with a tube amp, at LEAST carry some spare fuses, and if you can, a spare set of tubes and a preamp tube or two. Hopefully you'll never need it, but if you do it will cover you in about 90% of situations. If your amp has 4 power tubes and blows a fuse, it's likely a bad tube and you can take two out, see if it blows again. If not, then replace the fuse and rock on... if so, take them out, put the other two tubes back in and rock on.

Pete
 
My list would be long. Bottom line, If you own guitars and tube amps, you should invest some time and effort into learning how to use an iron. I'm a novice at best but I do enjoy soldering and can fix quite a few issues. I also love cable ties. A little hot glue and some cable ties can do wonders. I just went over my Friedman modded JMP and secured things a little better, not that Dave doesn't do a great job .Changed all of the caps as well. One was bulging and causing a little hum. Job cost me 70 bucks instead of 200 with a tech. I can do a mean setup on a guitar also, especially Floyds. The only thing I won't touch are frets. Not many techs can do frets correctly, even if they say they can.
 
Only trouble I've ever had and still have is.....Spending way too much money buying and trying amps only to end up right back where I started......Ghetto Rack and an old Marshall half stack
 
I've had bad luck LOL


Countless Marshall and Mesa issues....

Engl Powerball - 43 cold solder joints. Amp would cut in and cut out after an hour or so of use, was traced back to shitty build quality.

Axe FX was dead on arrival, replacement 1 -left output section failed 1 week after arrival. Sold after second replacement arrived. hahah

I've had other issues but can't remember them now, they were several amps ago hahaha.

Cheers!

C
 
I've never had serious issues with my amps other than replacing very old tubes on a Twin Reverb and blowing a fuse once on my Mark IIC+.
 
Only problem that wasn't tube related was a blown on/off switch on a Boogie Mark III, but I don't think it's unreasonable for a 21 year old mechanical switch to fail. Fortunately it happened at home and oddly enough I had a spare switch lying around.
 
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