Filter caps—Friedman Runt 50

[gkelm]

Hey, been a while! My login still works!

Could use a little help.

There is a low frequency hum, so amp needs new filter caps, according to Dave Friedman (bad batch). I can send it to him, but that’s shipping cost and sounds like he’ll charge me, and there’s a great tech here in Dallas as an option.

I think I want to replace them myself. I’ve done some minor stuff… Modding TS9s, replacing switches and input jacks, etc. I can solder well enough and I like to tinker, and understand possible voltage danger.

The current caps are: 47uf-500VDC 105*
Looking at these…physically smaller, but rated at 85* instead of 105. Does that make a difference?

https://www.mojotone.com/F-T-47uF-500V- ... -Capacitor

Not sure if the pics showed up, so here are links…
https://i.imgur.com/rwCFuDI.jpeg
https://i.imgur.com/YzSBhCK.jpeg

[xtian]

F&Ts are a good choice.

[maxkracht]

physically smaller, but rated at 85* instead of 105. Does that make a difference?

Temperature rating isn't always an even comparison, it's that temperature for a certain amount of time at the caps maximum rated values. An 85c rated cap could have otherwise better specs and perform as well as the 105c cap at 105c when derated for temperature. (have to check datasheets) You shouldn't be hitting maximum ratings or 105c, so this shouldn't matter. F&T are very reliable.

[Lauri]

If I remember correctly Friedmans have a very small thermal relief gap on the ground connections of the filter caps. You need to have a good soldering iron to be able to desolder them.

[gkelm]

Thanks, appreciate the help

[dorrisant]

F&Ts are a good choice.

Mod brand caps are great too... and smaller.

[WhopperPlate]

F&Ts are a good choice.

Fwiw my least favorite power filter cap, especially in a Marshall style circuit. Plenty of threads here where I rant about this.