Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: ARhodes on November 13, 2022, 08:08:05 am
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Hi everybody! I am a new forum member. I just bought a Mojo Deluxe Reverb kit. I have never built a guitar amplifier, but I have quite a bit of non-professional experience designing and building a variety of fairly complex circuits on custom PCBs. I can hand solder quite well. I have a LITTLE experience with tubes and hand point-to-point circuits with a single repair/refurbish of an All American 5 AM radio. Eons ago I was taught about vacuum tube circuits when I was learning material for a ham radio license.
My first (likely of many) question is about the eyelet board. I didn't like the idea of a big long floppy main eyelet board. So, I got the Hoffman G10 eyelet board in the fender-style layout. It looks wonderful.
But now where do I drill the mounting holes? The G10 board is wider than the original fiber board. It completely covers the pass-throughs from the doghouse. I was planning on mounting it on nylon standoffs anyway, and I think that 4 mounts somewhere near the corners will be sufficient. I am considering a 5th mount near the center of the eyelet board as well for added support.
Related question: How tall do you think the standoffs need to be?
I am looking for advice from people about this first step!!
-Tony
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I like 1/2" standoffs. There's some good info here...
https://el34world.com/Hoffman/instructions.htm
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Totally OK to cover up the doghouse passthroughs.
Some advice on drilling your mounting holes -- in order make sure the holes line up, I securely tape the board to the chassis, and check the orientation of the board relative to the chassis. Use a center punch to mark your holes on the board. Then drill your pilot holes through both the board and the chassis at the same time.
Do read Doug's instructions carefully as per Sluckey. There is valuable information in every sentence!
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Fantastic. I can do 1/2" standoffs easily. I will read that link now. I have a drill press and a variety of tools to get the drilling done and well aligned. I usually start with taping and then drill 2 holes diagonally opposite each other. I then install mounting screws to hold it more securely then drill the remaining holes. for 1/8" holes, I have 1/8" diameter hardened pins that I can insert in order to have less/no play compared to a 4-40 in a 1/8" hole. T think that 4-40 screws (4 or 5 of them) will have adequate strength while not taking up too much space under the board
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The Hoffman board install instructions that Sluckey linked will show you how to mount one of my boards
Standoffs all depends on what is below the board
You can go as low as 1/4" tall standoffs if you need to keep the boards really low