Voltage checking

[JamieMcC]

Doing the voltage checks on my crack is something I have been very nervous in going about.
This is most probably a good thing. However I would like some advice related more to the best way of supporting the cracks top plate while taking the readings rather than taking the readings themselves.

Some of my thought processes as this is not crystal clear in the manual for those of us prone to possessing special talents.

Upside down in the wood case, this does not seem like a good idea as the switch power switch is not accessible and the power cord means the upside down top plate will not lay flat and is unstable you also have no view of the tube filaments.

Upside down in case with case on its side, I worry about the top plate falling out, but again not very stable hard to reach power switch.

No case with top plate at 45 degrees propped up by something (pliers) put under the edge of the transformer bell housing to keep tubes clear of bench. (this is the how I took them)

None of the above feel like a good way to me of supporting the top plate while doing the voltage checks, am I completely missing a safe and easy way to support the plate for voltage checks?

I don't suppose someone who is familiar with testing could post a picture of how they support their crack whilst its live it really would help. 

I would certainly feel safer taking my readings if I was able to use a tried and tested method to do so.

Cheers

Jamie

 

[kgoss]

I think the most stable way to check is upside down in the case.  You can put some books or other solid material under two edges of the case to give you enough room for tall tubes to clear and a space for the power cord to come out under the case.  Be sure to turn on the power switch and apply power by plugging in the amp once its stable and ready for testing.  Don't try to reach under to flip on the power.

I wouldn't use a screwdriver or anything metal to prop up the chassis for voltage checks.  If you want to do it that way I think a towel is the best thing to use.  You can roll or fold it up to give you the proper support.

Just my 2 cents...

 

[galyons]

...

Upside down in the wood case, this does not seem like a good idea as the switch power switch is not accessible and the power cord means the upside down top plate will not lay flat and is unstable you also have no view of the tube filaments.

Above is my way for all BH products.  I route the power cord out under the base. The feet provide the space to do so.  If the tube doesn't clear, I carefully place the power tranny on the edge of the base.  Alternatively you can prop the base higher, to clear the tubes, with wood blocks or similarly flat material. Either way, flat or angled on the tranny is quite stable if you make sure the base is squarely in the relief. 

Angled on the tranny, the power switch is accessible.  Flat, I just lift the plate by its edge and turn on the switch.  Also it is simple to unplug the unit at the outlet, turn the power switch on before inverting the plate and then when all is firmly settled, plug it in.

Not rocket science,  but a bit intimidating for the first few times!

Cheers,
Geary

 

[mcandmar]

Upside in the base is perfectly fine, or as i built mine upside down in a cardboard box while to varnish dried on the base.

For safety (read the manual intro again) unplug the mains lead from the wall, place the amp upside in the box/base with the power switch on and mains lead connected, connect multimeter - lead, then plug it into the wall and carefully take measurements.  The back of the mains switch/plug on the amp is just as dangerous so you dont want to be fumbling around for the switch when its all live.

The process is a little unnerving, especially on the S.E.X. amp where some of the points are a little awkward to get at and have over 400v DC on them.  It reminded me of the game "Operation" where you had to remove parts with tweezers without setting off the buzzer

Basically just take your time and be careful of what you are doing so you dont short anything out, and again, read the manual as there are some very good safety points in there like insulating yourself by wearing shoes, keeping one hand in your pocket, and especially do not touch the amp with both hands.

As a rule i never lift the chassis plate with the AC cord connected, i'm just paranoid about those live terminals.

 

[Doc B]

The most straightforward approach is to plug the amp into a power strip that has an on/off switch. You leave the amp switched on, set it in the base upside down, plug it into the strip and control the power at that power strip switch.

 

[JamieMcC]

Super, thanks for the feed back guys. I have some work under the hood coming up and will incorporate some of the methods above next time I need to do my checks.

 

[STURMJ]

Power strip with a switch is a good thing to do too.