5E3 build question

[MarkL8]

Ive started my build and all is going well. Taking it slow and careful triple checking everthing. Heres my question when it is built is there a preferred way for the first startup? Or do most of you pop in the tubes and plug her in ?

THX

[hasserl]

Here's one way to do it. Pull all the tubes and fire it up, measure and record your voltages. If all looks good, no smoke and no popped fuses install the power tubes and remeasure and record the voltages, the b+ and plate voltage should drop considerably. If everything still looks good then install the preamp tubes and fire it up again and check/record the voltages one more time. If all looks good plug in and give it a real test.

Another good thing to do is to plug it into a current limiter for the first fire up to safegaurd against burning something up if you've got something mis-wired. You can build a current limiter using a light bulb as the limiter, into a two outlet electrical junction box. Install a light socket in one space and an outlet in the other, wire them in series so the current goes thru the light bulb first. If all is well the light bulb will light up bright then almost immediately go dim. If there is a short circuit in the wiring the light bulb will light up bright and stay bright. A voltmeter on the b+ at the same time will give more info.

[MarkL8]

Thanks Hasserl I should be ready by next weekend and will use your advice!

[Bruce / Mission Amps]

I like to start the amp with no tubes installed to be sure the filament supply is wired right and the on-off switches work.
I do this by making sure I am NOT touching the amp anywhere, the amp is unplugged from the wall and the main ON-OFF switch amp is on.
Then I use one hand and plug it into a wall outlet.
That way if there is some kind of bad mains 120vac wiring you are only holding onto a plastic and insulate power cord.
If it's all OK, fuse didn't blow and the pilot light is on...
BE CAREFUL HERE or you might wake up in a puddle of your own pee!
Check the HI-V secondary with a DVMM to be sure the rectifier tube has Hi-VAC on lugs 4 and 6 and all the sockets have filament voltage on the proper lugs.
Next I install the recitifer and check for unfiltered B+ at lug 8 and the standby switch.
When satisfied its OK, I flip the standby switch on and off a couple times VERY fast and leave it off, this is just to poke a little B+ into the filter caps.
Measure around the board and see if B+ is at the correct places... it doesn't matter what the value is as long as it was delivered to the right places.

If OK then I insert both preamp tubes.
Turn both volume pots to zero.
Flip the standby to on and in a few seconds you should be able to measure B+ across the plate resistors to lugs 1 and 6 and cathode voltage on lugs 3 and 8 of the nine pin sockets.
It will be a little high because the power supply is not loaded down by power tubes but at least you'll know the preamp tubes are turned on.
If thats all OK, I shut it off and insert a speaker load and the 6V6 power tubes.
Flip the mains ON-OFF to ON and wait a minute or so to be sure the filament supply is heating the power tubes.
IF OK... turn the standby to ON and measure the DC voltage across the 6V6's cathode biasing resistor.
If it is anywhere close to what you expect, 19vdc to 25vdc... it's time to see if makes any sound by plugging a guitar in and turn the volume up a bit.

[MarkL8]

BE CAREFUL HERE or you might wake up in a puddle of your own pee!

I know your dead serious about that but when I read it I damned near blew iced tea out my nose!

Please correct me if Im wrong. On the test points for the hi voltage stuff my DVMM black probe goes to ground then with the red probe the #4, 6 and 8 lugs and standby switch, correct? This same procedure applies to lug 1,6,3 and 8 on the nine pin sockets? Hopefully Im right so far.

Now the 6v6 cathode bias resistors that is the two 1k5 resistors on lugs 5 and 6 of the 6v6 sockets. For this test I would set my DVMM to DC volts black probe to ground and red probe to both lugs 5 and 6 to verify the 19-25 VDC ?? Sorry if this is a dumb question but while Im a Master Plumber by trade I sure aint and electrician..but Im learning. I just want to verify how to test this right...dont wanna wake up in a puddle of pee!!!

Thanks

Mark

[Bruce / Mission Amps]

>>Now the 6v6 cathode bias resistors that is the two 1k5 resistors on lugs 5 and 6 of the 6v6 sockets. For this test I would set my DVMM to DC volts black probe to ground and red probe to both lugs 5 and 6 to verify the 19-25 VDC ?? <<

The 1k5 resistors are grid stoppers and have nothing to do with bias.
The bias voltage of the power tubes comes from the cathode biasing resistor which is connected to lug 8 of the 6V6s.
It is self generated... or self biasing... or cathode biasing... all the same thing.
You would measure across the big blue 5w resistor on the eyelet board or from lug 8 to ground with the DVMM set to low'ish DC volts, looking for 19-25vdc.

You can connect your black lead to the cathodes, lugs 8, and then the red lead to lug 5 of the power tubes and this should give you about the same voltage as above but it will be negative now... that is the bias voltage too.