06/22/2013
PSA CARE AND FEEDING OF TUBE AMPLIFIERS!
Does your trusty tube amplifier need a little long overdue TLC?
An ounce of prevention is worth a pound of cure. This bit of sage wisdom never goes out of style – and for good reason. These days everyone is trying to save a buck and avoid unnecessary expenditures. When it comes to gear maintenance though, there are no shortcuts where long life and reliable performance are concerned.
Today we worked on a well-made small tube combo amp that needed both the output and power transformers replaced. This is an exceedingly rare occurrence in a run of the mill amp, and even rarer in high quality gear. The owner bought the amp used online, played it for a while and then parked it for some time. When an occasion to take it for a whirl arose he took it to the gig where it performed “OK” for the first set. Later the sound started dropping out until finally it began to emit smoke and went dead. The owner brought it to us and expressed great surprise that such a nice amp would go south like that.
Upon inspection we found that the amp had a good fuse in it but the transformer was blown, which was obvious when the amp blew the backup fuse in our test jig. The back-up fuse is there to protect gear under test if something unusual is going on. Something unusual was indeed going on, and it was the classic case of an oversize fuse having been installed in the amp, thus defeating the purpose of the fuse – to protect expensive components from damage. Because the fuse would not blow, the bad power tubes blew the output transformer, which overloaded the power supply and because this condition was allowed to fester, the power transformer ultimately overheated and failed as well.
Had the owner taken the amplifier in to be professionally checked out when he purchased it, he would have learned about the bad tubes and incorrect fuse. This knowledge, a new fuse and a fresh set of power tubes would have cost him around $100. As is turns out, a power transformer, output transformer and a set of power tubes cost him $400 – and we were running a flat rate labor special that week. It would have been over $500 at normal labor rates.
We’re in business to help you keep your gear in good working order and sell parts of course, but that doesn't mean we don’t feel for our customers who end up breaking their wallets over an easily preventable situation.
