Fender Bassman
There are lots of nice amplifiers from the vintage Fender camp, this one is one of my favourites. This little girl has been around the block a few times, but she looks good, smells good and sounds good.
The report was that, whilst all seemed to be working, there was a problem with random shot noises and various crackles. So, up on the bench and let’s have a look under her petticoat. Out with the chassis and powered her up, checking power consumption etc… Connecting a speaker and no input, there was a slight background hum and yes, the odd pop and crackle. This annoyed the client, especially when he used it in a recording studio. Scoping around, it was seen that the HT jumped around when the shot noises occurred. This suggested perhaps a, electrode short in one of the 6L6G output valves and or HT reservoir capdensors. One of the 6L6Gs did seem to be a little harmonic and played a Gm7 chord when gently tapped.
Off with the HT capdensor cover and it was soon clear where the fault was coming from. All the components here seemed to be original. Two of the larger capdensors had obviously been on a night out and vomited the contents of their tummies everywhere. So, all parts replaced. With the chassis upside down, all out of tolerance resistors and capdensors were replaced, along with new parts in the bias supply. A few of the coupling capdensors were replaced, but others were tested and found to be perfect, so they were left to fight another day. All the resistors around the output stage looked tired so were replaced. The output valves were tested and whist not 100% emission, they were left in place. With the cost of decent 6L6Gs and other valves going through the roof, get the most out of them I say. I still have quite a good stock of NOS General electric valves, but it is dwindling. The thought of buying Psvane valves with glass envelopes the thickness of half a human hair fills me with dread.
All back together and the controls cleaned up, she sounded great. Before being reunited with her owner, I will confess to giving her a cuddle.
Fender Bassman
Hay muchos amplificadores Fender clásicos buenos, y este es uno de mis favoritos. Este pequeño ha estado en el mercado varias veces, pero se ve bien, huele bien y suena bien.
El informe indicaba que, aunque todo parecía funcionar, había un problema con ruidos de disparo aleatorios y varios crujidos. Así que, subimos al banco y echamos un vistazo debajo de su enagua. Sacamos el chasis y lo encendimos, comprobando el consumo de energía, etc. Al conectar un altavoz y no tener entrada, se escuchaba un ligero zumbido de fondo y, sí, algún que otro chasquido y crujido. Esto molestaba al cliente, sobre todo cuando lo usaba en un estudio de grabación. Al observar, se observó que el amplificador de potencia (HT) saltaba cuando se producían los ruidos de disparo. Esto sugería quizás un cortocircuito en el electrodo de una de las válvulas de salida del 6L6G o en los condensadores de cápsula del depósito del HT. Uno de los 6L6G parecía tener un ligero armónico y tocaba un acorde de Sol menor (Gm7) al tocarlo suavemente. Quité la tapa del condensador de alta tensión y pronto quedó claro de dónde provenía la falla. Todos los componentes parecían originales. Dos de los condensadores más grandes obviamente habían salido de fiesta y vomitaron por todas partes. Así que se reemplazaron todas las piezas. Con el chasis al revés, se reemplazaron todas las resistencias y condensadores fuera de tolerancia, junto con piezas nuevas en la fuente de polarización. Se reemplazaron algunos condensadores de acoplamiento, pero otros se probaron y funcionaron perfectamente, así que se dejaron para otro día. Todas las resistencias alrededor de la etapa de salida parecían desgastadas, así que se reemplazaron. Se probaron las válvulas de salida y, aunque no emitían al 100%, se dejaron en su lugar. Con el precio de las válvulas 6L6G decentes y otras válvulas por las nubes, es mejor aprovecharlas al máximo. Todavía tengo un buen stock de válvulas General Electric NOS, pero está disminuyendo. La idea de comprar válvulas Psvane con envolturas de vidrio del grosor de medio cabello humano me llena de pavor. Ya todo junto y con los controles limpios, sonaba de maravilla. Antes de reencontrarme con su dueña, confieso que le di un abrazo.
Already read it and liked it Seth.
Funnily enough Fender are one of the major amps that I’ve never used. Seemed to remember back in the day when I was on guitar playing with a bassist using a Fender combo. Wasn’t impressed, it didn’t have balls but that could well have been the bassist. They’re a strange breed bass guitarists something to do with low frequencies addling the brain I think
Frequencies and beer?