Safely work on Bassman

[TR]

I have a 68 SF Bassman head that I want to work on, mainly a cap job and the Ruhl power/bias mod. I've seen a few different ideas on various posts on how to drain the filter caps. Any advice from experienced, safety conscious people are welcome, but I'd love to hear specifically from people who have worked on similar models. Please confirm or shoot down the following:

1. Clip a lead from chassis to plate 1 of 12ax7 with a power resistor connected - I have a 5 watt 100k. Turn standby switch on, but not power. Ready after a couple of minutes?

2. Lay a screwdriver across from the positive side of the filter caps to the chassis. This sounds like a bigger gamble since no resistor.

I understand the one hand rule. Should I also be wearing rubber gloves until I verify caps are drained? I have no qualms about taking extra precautions, so I'll wear a spacesuit if someone suggests it. I've worked with electronics before, soldered, etc, but this is the first time doing anything with filter caps. Thanks to anyone who can help me not get zapped.

[Jag]

I have 6 Bassmen (BF and SF). My usual procedure is, with the amp unplugged and the standby and power switches in "play mode", connect a lead from chassis to pin 1 of the first preamp tube. I don't think a resistor is necessary doing it this way, I've never welded anything doing it that way at any rate.

I do have a few jumper with in-line resistors that I use directly on the filter caps on occasion. IIRC I used 10K on mine.

I usually leave the jumper attached until I am done working on the amp. Just remember to remove the jumper before powering up.

Alot of people use the screwdriver method. It works but you could end up welding part of your screwdriver to the chassis.

[Bruce / Mission Amps]

I understand the one hand rule. Should I also be wearing rubber gloves until I verify caps are drained? I have no qualms about taking extra precautions, so I'll wear a spacesuit if someone suggests it. I've worked with electronics before, soldered, etc, but this is the first time doing anything with filter caps. Thanks to anyone who can help me not get zapped.

I think anyone who is so scared of the Hi-V filter caps in a little guitar amp.... that they would wear rubber gloves (or a space suit).... needs to find someone else to work on them from now on.
With the power off and the amp unplugged, drain the filter caps (high voltage B+ rail) with a wire using a clip lead on each end and a 1w 10K resistor in series to ground and you'll be fine.
By the way, you are about 100 times more likely to get seriously hurt from the
120v main line coming into the amp then anything else, other then dropping it on your foot.

[Jag]

By the way, you are about 100 times more likely to get seriously hurt from the
120v main line coming into the amp then anything else, other then dropping it on your foot.

Really? That actually gives me more confidence!

[TR]

Bruce,
I hadn't even mentioned the underwear I made out of anti-static mats yet.

I was mostly kidding with the rubber gloves question since I've have never seen anyone mention that, but not 100%. In my job, I've seen documentation on computer issues passed on by several people where all neglected small but important steps because they thought something was a given.

I think my only question at this point is, do I need to do both things (ground tube plate to chassis, connect positive side of caps to chassis through a resistor), or only one of those steps to drain everything? Thanks.