Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: KimboDb on August 24, 2017, 02:07:41 pm

Title: Stumped. 100 ohm resistors that connect to the heaters just burned up.
Post by: KimboDb on August 24, 2017, 02:07:41 pm

So i completed the build last nite. double checked the work and tested and powered up the amp last nite. The amp worked perfectly after i figured out that i didn't use shielded RCA reverb cables. had the amp on for about 30-45 min last nite. biased the tubes and tested it with a speaker.
Woke up and went to play it this morning and Both the 100 ohm resistor burnt up as i watched. i turned the amp into standby then off. burning stopped when i hit it to standby. then i turned it off a couple sec later.

Title: Re: Stumped. 100 ohm resistors that connect to the heaters just burned up.
Post by: sluckey on August 24, 2017, 02:30:25 pm

Burning those resistors is usually caused by a short between pin 3 and pin 2 on one of the output tube sockets. A short between pin 6 and pin 5 of one of the little tubes would also burn the resistors but not as quickly.

Title: Re: Stumped. 100 ohm resistors that connect to the heaters just burned up.
Post by: KimboDb on August 24, 2017, 02:44:38 pm

ok, ill check it out. Thanks. Ill check it out now