Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: ncusack on April 06, 2011, 10:03:04 am

Title: 10w resistor in 5w format
Post by: ncusack on April 06, 2011, 10:03:04 am

Hey everyone,

I'm working on a fender performer 1000 and there 2 5w 47R resistors in the dropping network for the power supply that keep overheating. I remember reading somewhere that there is a manufacturer that makes 10W resistors in a 5 W size and am wondering if anyone knows anything about this.

I can't for the life of me remember where I read about this but im hoping someone can suggest something here as they would solve the problem for good.

Cheers,

Neill

Title: Re: 10w resistor in 5w format
Post by: bobmegantz on April 06, 2011, 11:19:06 am

both 5 and 10W resistors come in a variety of sizes - check Mouser or Digikey.

Title: Re: 10w resistor in 5w format
Post by: overtone on April 06, 2011, 08:51:53 pm

I have found the Mills 12W wirewounds to be a similar size to the usual blue MOX 5W size.

But three things cross my mind in your case:
1. the heat will be the same for both Wattages because they are dissipating the same power.
2. have you calculated the expected Watts dissipated at these locations?
3. the overheating may be a symptom of some kind of issue elsewhere in the amp.

Best, tony

Title: Re: 10w resistor in 5w format
Post by: mageerc on April 07, 2011, 07:12:02 am

The Hot Rod series of Fender amps are famous for the problem you describe in your amp... what I have done in the past with the Hot Rod series is to mount the 5W resistors on a separate board from the PCB and wire jumpers to the PCB... this eliminated burning the traces on the PCB from the resistors being directly mounted on them...