DON’T DO THIS!!

[Chuck H]

I've often thought about adding an audible beep tone or a rotating light that's powered by energizing the outlet to the UUT so that I have an audible and a visual reminder when things are hot. But some of that just seems too geeky. Maybe I just need to keep one hand in my back pocket and behave as if everything is always hot.

Holy hell! That would send me into a seizure! Because I design rather than repair I do a lot of live testing and a rotating light would be like some sort of twisted hell when I'm trying to evaluate real time data before connecting a probe to the next station. But I could tolerate a single illuminated warning in front of my face. My bench is only about two feet deep so there's no way I could miss the LED being illuminated. Blinking, whirring and beeping aren't necessary

[bob p]

When I wrote that it was tongue in cheek -- I was thinking about that scene from the Andromeda Strain where the lady had a seizure when she saw a flashing warning light.

edit: here you go:

https://youtu.be/af7KHl2w7EU?t=100

[Chuck H]

A reference to "The Andromeda Strain"... Your showing OUR age

[Gnobuddy]

...I don't want to absent mindedly lean into something or have something that's electrified fall into me.

The rubber apron sounds like an excellent idea.

One of the scary stories I read on the 'Net was about a guy who was working on a valve amp (powered on) outdoors, shirtless, in hot weather. He didn't have the chassis properly stable and supported on his workbench, and it fell forward onto his chest, shocking the heck out of him. He didn't even have as much as a shirt on to help insulate his chest from the chassis voltages. He was probably sweaty too, which means he would have had much lower skin resistance than normal.

He was young and had a healthy heart, and as it happens, got away with nothing worse than a huge fright and a fair bit of pain for several days.

Nowadays, most of us who tinker with valves are "of a certain age", and our hearts are unlikely to be as robust as they once were.

I thought about the flashing light idea too, very briefly. Then I remembered the horrors of Microsoft's non-standard HTML "<blink>" tag in the early days of the 'Net. If you've ever encountered a website created with this monstrosity, you won't forget it in a hurry!

-Gnobuddy

[Chuck H]

On securing chassis... I don't do that right now. I'm not opposed, I just never dealt with it. For someone that does repairs I would think that securing every UUT in such a way that it's both safe to work on, by whatever criteria, and likely with some detriment to accessibility, then having to un secure it, would present too much time consequence. Maybe something like a 1.5" lip at the front edge of the work bench combined with a solid, adjustable system for blocking chassis up level would be safe enough.?. I'd forever be temporarily losing small tools and components behind even a 1.5" lip reveal, I know it. So what does everyone else do? Right now I literally use books to block up transformers and chassis ends for tube clearance on the bench top. This is about the worst "system". I've considered making some kind of heavy, wooden thing with adjustable blocks that have heat resistant rubber gasket material on the contact points. But it's pretty low on the list right now.

[J M Fahey]

A reference to "The Andromeda Strain"... Your showing OUR age

Just clicked your link .... you are referring to the *Movie*

I read ... ***the Book***

I guess that turns me into a:

[Gnobuddy]

So what does everyone else do?

Speaking only for myself, the main lesson I learned from that story was to actually pay attention to the stability of the chassis I'm working on - before I plug it in!

So I'll position the chassis, then give it a little wiggle or two to make sure it's not a house of cards waiting to fall. I'll route wires and guitar cables in such a way that I'm unlikely to accidentally yank on them and drop the chassis onto myself. The guitar cable being the most obvious candidate, I will typically loop this around a bench-vice or something else equally stable and heavy, so if I do accidentally tug on it, the force never gets transmitted to the chassis under test.

I've also taken to usually using one of those sticky soft-rubber shelf liner mats from the dollar store on top of my workbench, and under the chassis I'm working on. It's a lot harder to drag a chassis off a sticky rubber mat than to slide it off a smooth MDF bench-top!

It's not likely to be OSHA-approved (that would probably require a proper nationally certified, officially approved, chassis clamping device that costs $1500 and is permanently mounted to the work bench). But at least it's a few steps in the right direction.

-Gnobuddy

[Gnobuddy]

I read ... ***the Book***

I guess that turns me into a:

There are a lot of days on which I feel like Rip Van Winkle, having woken up in an alien future world where so much has changed that nothing makes sense any more.

It's probably a safe guess that nobody made a movie about the Rip Van Winkle legend?

-Gnobuddy

[prschmitt]

Hey! My first post!
What I did to prop up my first (still at the tweaking stage) build was to drill and tap 3 10-24 holes in the top of my chassis and thread short legs made up of cut off wooden closet rod having threaded rod glued into holes drilled into the ends.
I can then just flip the whole thing over on a flat surface.
Cheesy but effective.

Pete.

[bob p]

It's probably a safe guess that nobody made a movie about the Rip Van Winkle legend?

I thought of these. There are probably others.

https://en.wikipedia.org/wiki/Forever_Young_(1992_film)

https://en.wikipedia.org/wiki/Idiocracy

[bob p]

On securing chassis...
So what does everyone else do? Right now I literally use books to block up transformers and chassis ends for tube clearance on the bench top. This is about the worst "system". I've considered making some kind of heavy, wooden thing with adjustable blocks that have heat resistant rubber gasket material on the contact points. But it's pretty low on the list right now.

I do the same thing. I wedge a book, a block, a plastic box, whatever I can find, under the transformers so that the amp isn't resting on the tubes. Problem solved. I really should build one of those amp cradles, or better yet a cradle rotisserie like the car guys use to do frame-offs. but I haven't bothered because everything is a different size. Sure, I could make one that has adjustable slide-to-width, but I've just never bothered. The blocks are working OK for me. It's a bad habit, I know.

On the subject of rubber mats -- make sure you're using non-conductive rubber. There is a difference.

[bob p]

One of the scary stories I read on the 'Net was about a guy who was working on a valve amp (powered on) outdoors, shirtless, in hot weather. He didn't have the chassis properly stable and supported on his workbench, and it fell forward onto his chest, shocking the heck out of him. He didn't even have as much as a shirt on to help insulate his chest from the chassis voltages. He was probably sweaty too, which means he would have had much lower skin resistance than normal.

The risk of electrocution is but one of many reasons not to solder naked.

I think that guy would have to be the equivalent of the sportbike "squid" who rides a Ninja wearing only a Corona t-shirt, shorts and flip flops as protective gear.

[Chuck H]

Indeed! I actually can't remember the last time I worked in a live amp without a shirt on. Maybe I'm stodgy?

[nevetslab]

On securing chassis... I don't do that right now. I'm not opposed, I just never dealt with it. For someone that does repairs I would think that securing every UUT in such a way that it's both safe to work on, by whatever criteria, and likely with some detriment to accessibility, then having to un secure it, would present too much time consequence. Maybe something like a 1.5" lip at the front edge of the work bench combined with a solid, adjustable system for blocking chassis up level would be safe enough.?. I'd forever be temporarily losing small tools and components behind even a 1.5" lip reveal, I know it. So what does everyone else do? Right now I literally use books to block up transformers and chassis ends for tube clearance on the bench top. This is about the worst "system". I've considered making some kind of heavy, wooden thing with adjustable blocks that have heat resistant rubber gasket material on the contact points. But it's pretty low on the list right now.

I make use of a pair of lab jacks, one at each end on chassis' that don't fit into my Marshall cradle (Fender Twin-size chassis sit firmly on top of that Marshall cradle that JCM 2000's, JCM 900's and 800's fit into. In some cases, I have to bolt on wooden wings whee there's no chassis left beyond the transformers at each end, such as Mesa Dual & Tripple Rectifier chassis. you can crank the height up enough to be able to unplug tubes, and install bias probes.

I do need a trough below the edge of the bench, as I'm forever loosing that one-of screw that drops off the bench, hits the floor screaming 'FREEEEEEE' on it's way down to freedom. I spend a lot o ftime on my belly searching for those N-1 hardware items!

[DrGonz78]

I was working on a Roland 60D Cube amp about year ago and made a simple mistake while checking the B+ voltages. You see there are 250ma inline fuses in the -/+ power supply. So went about removing the board all the while testing voltages on the pins respective -/+ pins of the LM3886 chip to detect voltage. Nothing was detected so I figure the B+ had bled to ground through the circuit. I replaced the burnt out chip and then started to reinstall the boards back into the amp. I bumped something to ground and a nice blue flash discharged the caps. It startled me a bit but I was more confused than anything. Then I realized pretty fast that the 250ma fuses were open and since that was the case the caps held a full charge waiting to zap something. If those fuses were not open then when turned off the voltage would bleed off. Instead the voltage would sit there for a long long while. Not a huge deal but still I felt like a moron at that very moment.

Edit: Memory of exact event is foggy as I might have not removed the chip at that point until I started getting voltages going again. All I can say is even 40v flashing blue will surprise you when your not expecting it.