Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: YardBirdFan on May 16, 2012, 09:03:48 pm

Title: Power Capacitor Clearance Question regarding safety
Post by: YardBirdFan on May 16, 2012, 09:03:48 pm
Hi,

I have a home built amp head that I am building a cabinet for.  It is a Hoffman H50 with a hotswitch circuit added.  It sounds AWESOME but cuts out a bit due to some loose solder connections soon to be fixed. 

The way I purchased it was simply in the aluminum chassis that holds the parts together.  Transformers and tubes on top, everything else (including power caps) inside.

My question is about shielding, safety and power caps.  The caps are mounted internally, hanging from the top of the inside of the chassis.  I was thinking of lining the bottom of the wood cabinet with aluminum sheet stapled in for an added level of shielding.  The leads for the caps would be only about 1 quarter inch from the aluminum however.

Is there a chance that a spark might arc to the shield?   Should I avoid this extra shielding to be safe? 

Thanks!
YardBirdFan
Title: Re: Power Capacitor Clearance Question regarding safety
Post by: thermion on May 17, 2012, 04:25:12 pm
you could put insulation on the cap leads, like heat-shrink tubing or a piece of stripped wire insulation. you could also paint an insulating layer onto the aluminum shield with a product such as this:

http://solutions.3m.com/wps/portal/3M/en_US/EMDCI/Home/Products/Catalog/~/Scotch-Insulating-Spray-1601-Clear-16-fl-oz-can?N=4294792703+5427538&Nr=AND%28hrcy_id%3AGS158F27QDgs_B8KCK2X5GP_N2RL3FHWVK_GPD0K8BC31gv%29&rt=d (http://solutions.3m.com/wps/portal/3M/en_US/EMDCI/Home/Products/Catalog/~/Scotch-Insulating-Spray-1601-Clear-16-fl-oz-can?N=4294792703+5427538&Nr=AND%28hrcy_id%3AGS158F27QDgs_B8KCK2X5GP_N2RL3FHWVK_GPD0K8BC31gv%29&rt=d)

Title: Re: Power Capacitor Clearance Question regarding safety
Post by: stratele52 on May 18, 2012, 04:51:32 am
Yardbird , 1/4 inches is lot of space . No problem with spark. This is a standard way to mount caps
Title: Re: Power Capacitor Clearance Question regarding safety
Post by: YardBirdFan on May 21, 2012, 01:58:51 am
Thanks for the replies.  To be safe I found some vinyl that was originally designed for protecting the lower portion of your rocker panels from rock chips.