Military projector amp - last edited 9/26/22 - layout help needed

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yello
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Re: Military projector amp - edited 9/13/22 layout help needed

Post by yello »

I should grab a photo of the switch and the turret board. Convoluted and hard to get to mess of wires. This is an instance where deciphering from the schematic will be way easier than from the real world amp....
JMPGuitars wrote:
Fri 09/16/22 2:31 pm

There are quite a few rotary switch types. As long as you can find the type of switch, the rest is a matter of confirming with the schematic what connects where. And for the layout, you make that clearer than reality.
Bieworm wrote:
Sat 09/17/22 4:16 am
You first have to figure out the way the connections work on the switch. There should be 2 common terminals which connect to one other with every switch.

Draw this out... and then figure out which components should interconnect
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Re: Military projector amp - edited 9/13/22 layout help needed

Post by Bieworm »

If I can find some time to analyze that schematic I will try to help you out.
But I have a lot (7!!) of upcoming amp projects after this Princeton Reverb I'm building (finishing) right now. And there's this guy who dropped 3 hollowbodies at my place to replace electronics... I'm way busy.. but I'll try to help out.
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Re: Military projector amp - edited 9/13/22 layout help needed

Post by Bieworm »

Dayn.. this is not so cleanly laid out, but you can take it from here I guess?
5way switch.png
dayn 5 way switch layout.png
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Re: Military projector amp - edited 9/13/22 layout help needed

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Bieworm wrote:
Wed 09/21/22 8:12 am
Dayn.. this is not so cleanly laid out, but you can take it from here I guess?5way switch.pngdayn 5 way switch layout.png
THANK YOU! This is awesome, I couldn't get my brain to get it this far and its a huge help.

Hope your upcoming projects go well!
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Re: Military projector amp - edited 9/13/22 layout help needed

Post by yello »

I was able to find some more info about the tone control rotary switch I am trying to decipher.

First, a clean picture of this part of the schematic:

Image

Followed by a detailed description of what each switch setting is doing and what related parts it is connecting:

Image

Image

Image

Image

It is becoming more clear what is going on, but I need to review it a few more times.
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Re: Military projector amp - last edited 9/23/22 - layout help needed

Post by yello »

So after digesting Bieworm's great diagram, and looking at the detailed circuit info I found, it seems at first glance and reading that when the rotary dial is in the middle "NOR" position, that the extra caps/resistors from other parts of the switch are all bypassed as if not there?

Given I'd like to create a layout that captures only the "Normal" tone position, and basically eliminates that rotary switch, I think it would therefore be hardwired like this:

Image

My lingering question, that I can't seem to deduce from staring at it, is whether the highlighted portion of the switch wiring stays or is eliminate if the rotary switch and its caps/resistors and wiring are removed?

Here is the original circuit pic for reference:

Image
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Re: Military projector amp - last edited 9/26/22 - layout help needed

Post by Bieworm »

NOR bypasses C209, R210 and R212. If you want NOR you might as well delete C209, R210 and R212.
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Re: Military projector amp - last edited 9/26/22 - layout help needed

Post by yello »

Bieworm wrote:
Mon 09/26/22 1:02 pm
NOR bypasses C209, R210 and R212. If you want NOR you might as well delete C209, R210 and R212.
Thanks, sounds like I had it backwards asking about deleting the highlighted wire connection, instead needing to delete the components below it that are bypassed by the wire.

So like this?:

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Re: Military projector amp - last edited 9/26/22 - layout help needed

Post by Bieworm »

Looks correct to me..
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Re: Military projector amp - last edited 9/26/22 - layout help needed

Post by yello »

Bieworm wrote:
Wed 09/28/22 10:07 am
Looks correct to me..
I appreciate your help sorting it out, I know you are quite busy with the amp and guitar projects! This will help me finalize my layout.
JMPGuitars wrote:
Thu 09/15/22 7:59 pm
I draw components for layouts by looking at the actual component in the amp. Take good photos of it if it's hard to see.
Currently I'm creating a new layout for this amp circuit, so it can be built on a turret board in a typical amp chassis, not in the original projector enclosure which is crowded and convoluted. That means I'm not recreating what I see in person in my layout, but rather translating the original schematic and original layout, into a totally new (better) layout. Its a great learning process.
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Re: Military projector amp - last edited 9/26/22 - layout help needed

Post by JMPGuitars »

yello wrote:
Wed 09/28/22 12:05 pm
Currently I'm creating a new layout for this amp circuit, so it can be built on a turret board in a typical amp chassis, not in the original projector enclosure which is crowded and convoluted. That means I'm not recreating what I see in person in my layout, but rather translating the original schematic and original layout, into a totally new (better) layout. Its a great learning process.
That's great! And it also means you can do whatever you want. ;)
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Re: Military projector amp - last edited 9/26/22 - layout help needed

Post by yello »

JMPGuitars wrote:
Wed 09/28/22 8:01 pm
yello wrote:
Wed 09/28/22 12:05 pm
Currently I'm creating a new layout for this amp circuit, so it can be built on a turret board in a typical amp chassis, not in the original projector enclosure which is crowded and convoluted. That means I'm not recreating what I see in person in my layout, but rather translating the original schematic and original layout, into a totally new (better) layout. Its a great learning process.
That's great! And it also means you can do whatever you want. ;)
I will likely mimic the layout sections of the 18w, as that worked out great when I built my ef86 Lite 2p.
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Re: Military projector amp - last edited 9/26/22 - layout help needed

Post by yello »

Here is a question, as I draw up my own new layout for this circuit:

There isn't anything that connects to filter cap C216B - it is connected to filter cap C216A and C216C via a 350 ohm 3w resistor on either side (R240 and R228). What is the point of that? Can I just eliminate C216B and just up the resistor size between C216A and C216C? Would the resistor be 700 ohms 5w? Or 1k or 1.5k 5w? Or does cap size need to change too?

In other words, can I redesign this filter stage to work better and without (what seems to my inexperienced eyes as) extraneous parts?

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