blown screen resisitor

[bluesboy]

hi all, thanks for the input. i know all about discharging capacitors, so no need for alarm there.

 

anyways, last night i went over to take a look. we pulled the chassis, and looked all around and nothing was obviously damaged or burnt looking. im glad too, because the inside of the TSL isnt exactly "mod friendly" or "tech friendly" looking.

 

we ended up changing the fuses, put new tubes in. biased it, and voila everything worked fine.

[Johnny Z]

 

Screen grid. A 1-2watt resistor for 6L6's in not enough. Fender used low wattage resistors so they would blow and they do, 5 watt rated resistors will last damn near forever. What I use.

 

 

I know some people use higher wattage grid resistors, which is fine. I never had any problems using 1 watt in a Fender, it's what the schematics call for. The usual reason the grid blows is because of a short in the tube. Even a 5 watt will blow if the screen grid in the tube shorts but your risking other damage before it blows.

[Johnny Z]

Not always, 1watt screen resistors blow because they're underratted for the job. They get hot, even 5 watt units get hot. 1 watt is a

 

Are you an electrical engineer?

 

How long have you worked on amps?

 

What ever, better a grid resistor than a melted PC board or a output tranny. I'm not a an expert but I trust Leo knew what he was doing, my vintage Fender amps remain stock and have seldom had any problems. As a hobbiest and old amp and radio junky I've replaced several grid resistors over the last 30 years on many amps, radios and what ever, everyone was caused by a shorted tube. Most of them were in the last 10 years because modern tubes are shit and some new amps are pushed too hard with increased plate voltage for higher gain and output.

 

But what ever, do it your way and I'll do it mine.

[tommythelurker]

Are you an electrical engineer? How long have you worked on amps?

 

http://www.roccaforteamps.com/