Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: coreysan on March 14, 2013, 12:39:11 am

Title: AB763 One Channel Project - Schematic vs. Layout vs. Pictures Don't Match
Post by: coreysan on March 14, 2013, 12:39:11 am

Hello all. I'm gearing up to build the AB763 One Channel Project, and I noticed that there are differences between
the schematic and the layout diagrams.

There are also differences between the diagrams and the GIF picture I looked at of the Super Vibrolux that was built.

Since there's differences between all three, which one gets priority, or will all three work well?

For example, the schematic shows underboard wires soldered to the left of a 1K resistor, while the
layout shows the wires soldered to the right of the 1K resistor.

Also, the schematic and layout diagrams show at least 2 resistors that I can't find anywhere on the
board as shown on the GIF picture, and the placement of a few caps ignore lugs that the diagrams utilize.

Just wanting to be sure!

Thanks for any reaction!

Title: Re: AB763 One Channel Project - Schematic vs. Layout vs. Pictures Don't Match
Post by: kagliostro on March 14, 2013, 03:38:32 am

It will be easier to us to follow you if you post the images or link

K

Title: Re: AB763 One Channel Project - Schematic vs. Layout vs. Pictures Don't Match
Post by: sluckey on March 14, 2013, 08:16:58 am

Quote

For example, the schematic shows underboard wires soldered to the left of a 1K resistor, while the
layout shows the wires soldered to the right of the 1K resistor.

The pic with the grey board is in error use this layout instead...
(http://www.el34world.com/Hoffman/images/AB763OldOneChannel.gif)

Quote

Also, the schematic and layout diagrams show at least 2 resistors that I can't find anywhere on the
board as shown on the GIF picture, and the placement of a few caps ignore lugs that the diagrams utilize.

What schematic? Do you mean the pic I posted above? Which 2 resistors are you talking about? Some components are mounted on the tube sockets.

I would use the layout I posted to build the amp. Forget about the grey pic. Use the photos for reference ONLY.

Title: Re: AB763 One Channel Project - Schematic vs. Layout vs. Pictures Don't Match
Post by: coreysan on March 14, 2013, 01:51:32 pm

Thanks Steve - by schematic I should have said the "old" vs. "new" layout.
The layout that's in full color shows 2 underboard wires that connect to
a 470 ohm resistor, and then up to pin 4 of the 6L6.

The non-color layout showed the wires connected to 22 cap, that goes
up through a 100K resistor then a .1 cap.

So if this full-color layout is the correct one, can you confirm?

I'll work on indicating the resistors I was talking about and post them,
unless you can confirm this: if I follow the full color layout, then no matter
what any other pictures look like, if I get confused, I'll just stick to this
one.

Would you agree?

Corey