tilting tubes for service

brad44

Active Member
Im real nervous tilting an amp on its side.... is that hard on the tubes? How durable are they in general?
 
The danger is from the weight of the transformers overturning the amp and crushing the tubes in the process. The tubes themselves will be just fine running on their sides or even upside down for the length of time you will have it under service. Indeed, most tubes are fine spending their entire service life on their sides, as they did in a great many TV's of the 50's and 60's.

Shelly_D
 
There are a few tubes that shouldn't be operated horizontally, or must be oriented in a specific way if they are. These are usually 'directly-heated' tubes such as the 5U4 rectifier, where the hot filament can sag far enough to come in contact with the anode. Here's what the 5U4 datasheet says:

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There are a few tubes that shouldn't be operated horizontally, or must be oriented in a specific way if they are. These are usually 'directly-heated' tubes such as the 5U4 rectifier, where the hot filament can sag far enough to come in contact with the anode. Here's what the 5U4 datasheet says:

View attachment 938191

You beat me to it! Good advice!

Mark T. :music:
 
When laying in different positions, just make sure nothing is pushing on the tube bending the tube pins in the socket. Tubes are durable unless you drop them on a cement floor..
 
I whacked together a couple stands like this to turn my amps upside down, and well supported... the sides are just screwed in from the bottom, and can be easily moved to accommodate a lot of chassis,,, tubes are always vertical...
 

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I'd suggest even the 5U4 is ok if you can justify that it is not running close to it's PIV specs, and the heater is not a highish level. Initial testing for example with a Variac to set up amp stage biasing, and where the diode anodes have ss diodes in series.
 
Tip it over. But please DO make sure the Weight of the transformers is on the BOTTOM. Helps keep it stable.
 
Some tubes have restrictions as to their orientation during operation. The data sheets will spell it out for you.
 
All audio tubes are designed to operate in the vertical plane and some can operate in the horizontal. So, when working on a tube amp i use small blocks of hard foam to place under the transformers and/or chassis to keep the tubes elevated and the chassis more or less horizontal. Sometimes a slight tilt allows better access. Just be careful that the tubes are not touching any of the pads.
 
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Woah, working the chocolate beast on a glass table that is brave. You should get a real work bench with a 6" vise and bench grinder/wire wheel combo. It is amazing how handy those tools are.

I was just setting the bias and balance on its initial fire up. No special tools necessary.
The whole weight of the deuce is on the one OPT. It's remarkably stable.
 
I was just setting the bias and balance on its initial fire up. No special tools necessary.
The whole weight of the deuce is on the one OPT. It's remarkably stable.
Yeah that amp is quite heavy, almost 60 pounds, I was mostly worried about the glass top. Glass , usually, fails catastrophically. And it could be something minor, like dropping a screwdriver or other tool hard end first, on the top that makes a small fault and compromises the integrity of the entire piece.
 
Hey primosounds, I have safety implements in place for such catastrophes.









........my feet ;)
 
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