Just for fun: Attempt at #40 schematic...

[heisthl]

Just attach the print with double sided tape and drill.

[ic-racer]

Here is a rough, rough draft of a layout. Still only about 1/2 way there, but the missing parts are pretty standard.

I wanted to get the unique things done first, like the main board, the single relay wiring, the front switches (slide switches, so the wiring is upside down from the 'usual') and the cathode ground arrangement on the 6l6s.

[ic-racer]

I was curious about the wiring of the relay on #40. The photos show it real well (as shown in the layout I posted), but it did not make any sense in the context of any relay wiring I was familiar with.

However, I found this relay schematic that I bet was similar to the relay on #40. Now the wiring makes sense.

[ic-racer]

Updated #40 schematic. A bunch of small details added and errors corrected.

[Runaway J]

Hi IC,

maybe you could use this pic for your schematic
(if you don't have it already).

BTW great work, many thanks!

Juergen

[ic-racer]

That is very helpful. I can see that there is a second ground coming off the back of the capacitor board. The other pictures did not show this area.

Also I have found the 'hidden' resistors!!! They are right between the two large caps, like I figured, after seeing the Winterland pictures.

[bluesfendermanblues]

Impressive work

- is the schematic/layout identical to the 70's schem?

[ic-racer]

Impressive work

- is the schematic/layout identical to the 70's schem?

On the schematic the component values without anything after them are from the 70s schematic. All others have a letter in parentheses that denotes where the value came from. There are quite a few differences from the 70s schematic.

I'll probably populate the layout with the same values as the schematic. So the layout and the schematic will be as close to #40 as I can get them.

I finished the layout last night and now can start to cut the boards.

[ic-racer]

Well, here it is, the layout for #40. It was a little more work than I thought, because I had to draw all the components, as I did not have any kind of component library or anything like that.

I did not include the PT's main's wiring because I have no clue how that 'international' PT is wired to the switch. I'm going to put a standard US voltage PT in mine, but did not want to put that in the layout because it's not what is in the actual amp. So I just left that portion of the wiring out.

I did not put values on the OD entrance components because I presume I will have to tweak to find the ones that work. Same with the two caps on the Bass pot. Either way, the layout goes hand-in-hand with the schematic.

[UltraHookedOnPhonix]

Beatiful work! Very nice job!

This is probably common knowledge but the Triad xformer marked, "17-7806" denotes batch code followed by a date code (6th week of 1978). Maybe label the filament transformer with F-313X instead.

Here's the datasheet for anyone interested:

[ic-racer]

Beatiful work! Very nice job!

This is probably common knowledge but the Triad xformer marked, "17-7806" denotes batch code followed by a date code (6th week of 1978). Maybe label the filament transformer with F-313X instead.

Here's the datasheet for anyone interested:

I did not know the date codes on these, thanks for the info. I was trying to figure out if the pictures posted by runaway 3 were of an amp earlier or later than #40, but the date codes on the transformers are too close to each other.

[Runaway J]

The pic is one I copied amongst others from ebay some month ago.
Here is the complete set. The amps serial number starts with 3, so it shouldn't be much older.

Cheers,
Jürgen

[ic-racer]

Thanks for posting the pictures.


Well, the more I think about it, actually making this amp won't be that hard. The hard part (the layout) is already done. The rest of it is just soldering everything together.

Here are the boards, ready for components.

[dogears]

Wouldn't that be serial number 3X as in thirty something?? As in the poster did not want to divuge the serial??

The pic is one I copied amongst others from ebay some month ago.
Here is the complete set. The amps serial number starts with 3, so it shouldn't be much older.

Cheers,
Jürgen

[ic-racer]

Re-thinking the cathode resistor on the 6L6s.

When I first saw this resistor (under the 'death cap') I figured it was a one-ohm bias resistor. However, it looks like it is connected to the cathodes of both tubes (via the yellow wire). So, one just halves the value and you get an average for both tubes. But this does not really seem like the thing HAD would do. He certainly would want to know each tubes individual current.

Then I was working on my Sundown amp and realized both of its 6L6 cathodes were also tied together. They run to a rheostat that can limit the output.

Then I thought that perhaps #40 was set up to be a 'low power' or 'half power' amp. Not everyone needs 50W and perhaps if that is like a 200 ohm resistor it would cut the power to like 25W. Sort of a built in power attenuator.