Hold My Hand While I Build My First Tube Amp

[NoDough]

Hello internet electron wizards.

So I've been working my way towards building a tube amp over the past 2+ years. Cutting my teeth on guitar pedals, microphones, and preamp kits, but now I've decided to take the plunge into the big time with high voltages and eyelet construction. So I was looking for a place to hold my hand as I started this journey and I'm hoping the intelligent folks I see around these parts can answer the abundance of questions that are popping up on my new foray into this deeper, more dangerous forest.

So this is the current status of my princeton reverb clone kit. Just starting out and installing the hardware.


These are the questions that have popped up thus far:



1) Pilot lamp and filament wires are touching the chassis.
    I reached out to an amp repair technician I know and he suggested electrical tape. I had read on another forum to potentially use rubber. Does anyone have any pros/cons against using either? I'm leaning toward the rubber fix as it will be just a little bigger separation, but I could be convinced otherwise.


2) Determining the bias board / bias pot location
    So I'm trying to figure out an ideal placement for my bias board and the pot. In its current location it is a bit of a tight squeeze with the cap can, board and pot. I could potentially change the output transformer wires to a different grommet, but I kind of like this current location. Would there be a reason my current location would be problematic?

3) Cap can is touching the chassis
    I used the ol' trusty dremel to bore out some of the cap can opening as it wasn't going to fit othewise, but 1 outer tab of the cap can is still touching the chassis. As all of these are going to ground I assume this is not a problem, but I may be misinformed in this thinking. Should I dremel out a little more of the chassis to keep the cap can tab from touching the chassis?

There will be many more questions to come, but for now I figured this would be a nice start and introduction. Thanks!!!!

[shooter]

can you rotate the light assy to clear?
I'd verify twice that tab is ground on the cap can, if so you're good(ish)

[NoDough]

Shooter thanks for the reply! So your suggestion to rotate the assembly has proved to be a solution that creates more questions.

So I turned the pilot lamp and bent some of the metal. This gives me the tiniest bit of clearance from the chassis.



But it also presents what I don't think is a problem, but I just want to check. So now the metal "housing" for the bulb is touching up against the sides of the lamp holder. I assume this isn't a problem? But please educate me if this assumption is in error.



Lastly here a pic from the layout showing the cap can.



To my eyes all of the outer tabs of the cap can will be jumpered together and taken to ground. Let me know if this is incorrect.

Thanks!!!

[acheld]

Curious, which company is the kit from?

[sluckey]

Fender mounted the bias board between the PT and the front panel. Like this...

     http://sluckeyamps.com/64DR/08.jpg

The lamp socket MUST NOT TOUCH THE FRAME! Use your ohm meter to check for continuity between chassis and the two solder lugs on the back of the lamp holder. Resistance must be infinity.

You do not need to run a wire from all four ground solder tabs because all four tabs are just part of the metal can, so they are already connected.

The layout drawing is a Weber 6A14 kit. And no other instructions. Not a good choice for a first build if you need your hand held.

[jordan86]

What chassis is that? Unfortunately the PT cut out is WAY closer to the pilot light and front plate of the chassis than a normal Princeton. I don’t think there’s anyway you fit the bias board and bias pot up there. I’d try to get it somewhere between the cap can and the rectifier tube.

[Blueboozer]

Maybe something like this might be better for the pilot lamp

https://www.tubesandmore.com/products/dial-lamp-front-panel-indicator-light-relampable

[Bieworm]

Why are you worrying the metal part of the pilot light touching the chassis? After all it touches the chassis behind the faceplate... that is the same part that touches the bottom...
Don't let the lightbulb  touch anything else than its fitting... or the fuse will blow. Been there , done that...

[mresistor]

According to the layout the bias board goes up underneath the front panel next to the pilot light like all the other PR chassis.  There should be a hole drilled there for mounting.   https://tedweber.com/6a14-c-kt/


Did that power transformer come with the kit?

[mresistor]

The Weber layout also shows the bias pot mounted between the output transformer holes in the area between the power tubes and preamp tubes, however I usually mount it just to the control panel side of the cap can so the wires are much shorter. See the Deluxe Reverb layout - red circle would be location of the cap can in a PR.

[mresistor]

Here is where I mount the bias pot in a PR chassis.  You will have to drill a hole for it there.

[NoDough]

Curious, which company is the kit from?

As many have said this is a kit from Ted Weber Speakers. Feel free to google if you want more information about them, I won't directly link as I believe this forum is more geared toward Hoffman amplification. 

[NoDough]

The lamp socket MUST NOT TOUCH THE FRAME! Use your ohm meter to check for continuity between chassis and the two solder lugs on the back of the lamp holder. Resistance must be infinity.

You do not need to run a wire from all four ground solder tabs because all four tabs are just part of the metal can, so they are already connected.

Sluckey,

Thanks for the advice!! Really appreciate the insight. So the direction I had turned the lamp holder turned out to be very problematic. Without the jewel installed continuity was fine, but the second the jewel was installed everything started to beep. So I had to turn the lamp holder back to the original direction. Here things got better.

So I found that if I push the lamp holder slightly down into the chassis I have continuity to ground thus resistance (in this case 260.3 ohms)



If I conversely lift up on the lugs to keep them off of the chassis I get infinity resistance as you said.



Now the difference between a problem and not a problem in this position is a little too close for comfort. Do you recommend something other than rubber or electrical tape? I think rubber would ease my mind a little more, but looking for advice. Thanks again for saving me from future pain! 

Also thanks for the picture of Fender's work. I was on the fence between whether or not to use some solid core wire I already had laying around, but it looks like Fender used some back in the day so it probably won't be a huge issue if I save some money and use some stock wire.

[NoDough]

According to the layout the bias board goes up underneath the front panel next to the pilot light like all the other PR chassis.  There should be a hole drilled there for mounting.   https://tedweber.com/6a14-c-kt/

So Weber has not pre-drilled a place for the bias board on the chassis. I have decided to relocate the bias pot to a location that someone on the Weber forums had used.



My biggest worry I think is crosstalk with these wires. Someone with more experience may be able to drop some knowledge on whether this may be problematic or not.

Did that power transformer come with the kit?

No that is not the stock transformer. Another user on the forum had chosen Mercury Magnetics transformers for their build and I followed suit. These are Fender Deluxe Reverb "Clones" as these correctly fit the chassis for Weber's build. I believe they should work, but I am going to e-mail Mercury Magnetics just to double check before I get too involved.

[sluckey]

Now the difference between a problem and not a problem in this position is a little too close for comfort. Do you recommend something other than rubber or electrical tape?

Almost anything that's non-conductive will work, index card, poster board paper, credit card, even a business card. Or cut a rectangle from a plastic gallon milk or water jug. Be creative. Lot's of everyday stuff around the house will work. You're only dealing with 6.3VAC.