#124 Layout questions

[lgehrig4]

Hello!

I'm building this amp using an Amplified Nation chassis and boards and, for the most, following the most recent iteration of the layout from the A Collection of #124 Information (Schematics, Layout, etc.) thread.

The amp I am building will not utilize the 10uf/10uf cap and the power supply is different than the layout. I have a few questions about the board. Attached is a photo of the power supply(not mine but the same) and screenshot of the of the section of the board where I have these questions.

1. In the layout there is a red wire running from the 2nd 100K resistor from the 2nd pair, that runs under the board to the 10uf/10uf cap. Since I'm not using this cap should I run this directly to the power board or is there something else that I need to do?
2. Am I seeing this right. It appears that the brown wire from the master center log runs to a rear jack, but instead of running straight through its two separate wires soldered together on tjhe board. Any reason for this?
3. Where does this grey bias wire run to? The center lug of the bias knob? If so am I adding a 220K resistor between the wire and pot? It just says 220k for some reason but there is no resistor drawn.
4. Where does the green wire from the .02uf go? It just cuts off as it intersects with the blue wire from relay, but if green/blue were to be connected I would imagine this would be drawn differently.
5. This is more out of curiosity. Why does the ground from the 1uf (I'm using tantalum) cap run under the board to the jack rings instead of taking a short trip to the ground bus?

Bonus question not numbered in the layout Next to the brown wire from #2, there is a green wire that runs from the same jack and then leads to nowhere. No dotted line showing where it runs to. Where is this one heading?

I appreciate in advance any help I can get. I'm slowly trying to learn to read schematics at the moment its a bit much for me with an amp like this.

Thanks!
Jeff

Screenshot 2025-03-07 at 7.30.54 PM.png

Screenshot 2025-03-07 at 12.52.32 AM.png

[Thomas_H]

help us here and add the schematic you are using to your post. The schematic has all the answers in a more readable form.

[dbharris]

You may get more views in the discussion section...

Hello!

I'm building this amp using an Amplified Nation chassis and boards and, for the most, following the most recent iteration of the layout from the A Collection of #124 Information (Schematics, Layout, etc.) thread.

The amp I am building will not utilize the 10uf/10uf cap and the power supply is different than the layout. I have a few questions about the board. Attached is a photo of the power supply(not mine but the same) and screenshot of the of the section of the board where I have these questions.

1. In the layout there is a red wire running from the 2nd 100K resistor from the 2nd pair, that runs under the board to the 10uf/10uf cap. Since I'm not using this cap should I run this directly to the power board or is there something else that I need to do?
2. Am I seeing this right. It appears that the brown wire from the master center log runs to a rear jack, but instead of running straight through its two separate wires soldered together on tjhe board. Any reason for this?
3. Where does this grey bias wire run to? The center lug of the bias knob? If so am I adding a 220K resistor between the wire and pot? It just says 220k for some reason but there is no resistor drawn.
4. Where does the green wire from the .02uf go? It just cuts off as it intersects with the blue wire from relay, but if green/blue were to be connected I would imagine this would be drawn differently.
5. This is more out of curiosity. Why does the ground from the 1uf (I'm using tantalum) cap run under the board to the jack rings instead of taking a short trip to the ground bus?

Bonus question not numbered in the layout Next to the brown wire from #2, there is a green wire that runs from the same jack and then leads to nowhere. No dotted line showing where it runs to. Where is this one heading?

I appreciate in advance any help I can get. I'm slowly trying to learn to read schematics at the moment its a bit much for me with an amp like this.

Thanks!
Jeff

Screenshot 2025-03-07 at 7.30.54 PM.png


Screenshot 2025-03-07 at 12.52.32 AM.png

1. You are using a single a 20uf cap on the main power supply board. The last one in the chain. You would run the B+5 wire from there to the plate resistors at V1.

2. That is correct.

3. This wire connects to the junction of the 2 220k resistors in the phase inverter section of the main board.

4. It wraps under the board towards the tube side where the other green wire is connecting to the loop jacks. Also, the answer to you bonus question.

5. HAD was particular about his star grounding preferences. There is a ton you can read on here about that. Different blocks of the circuit ground to different locations for lowest noise.

I agree that you will be better served if you try to reconcile the schematic with layout to understand how it all works.

-Dan

[lgehrig4]

Thank you dbharris!

I'm pretty much following this layout and photos so far, but in regards to the #3(bias wire), I can see that it connects to the 2 220k resistors, but I was referring to the other end. If you check this schem it's just labelled Bias. It would make sense that this connects to the other Bias label on the 10K pot, but I don't want to assume since there is no clear line connecting the two.

Also , the layout says Bias 220k. Does this mean that I need to add another 220k resistor or is it telling me that I am resolving this to the other wire labelled Bias that is connected to the 220k resistors?

Screenshot 2025-03-08 at 3.12.53 PM.png

#124 Schematic 1984.pdf

[martin manning]

You are correct, the bias pot wiper (center lug) connects to the junction of the 220k's. BTW for the layout posted in this thread the #124 schematic you should be referring to is the Skyliner version (not the 1984 version).

[lgehrig4]

You are correct, the bias pot wiper (center lug) connects to the junction of the 220k's. BTW for the layout posted in this thread the #124 schematic you should be referring to is the Skyliner version (not the 1984 version).

Thanks Martin!

[GAStan]

#2 seems to have been a common thing HAD did. Here's a pic of a BM he did it on. I do not know why.

Picture 110.jpg