First D-style (102) build opinions solicited & build thread:

[Raoul Duke]

Does it matter that my J/R switch is two position? The three position-type switch wasn’t apparent to my novice eye and I installed and wired a two position in its place. I can replace it if it’s necessary - but given where I’m at now; it’ll be a delicate surgical operation for me, lol.

[GAStan]

The center position gives PAB from the front panel.

[ijedouglas]

Does it matter that my J/R switch is two position? The three position-type switch wasn’t apparent to my novice eye and I installed and wired a two position in its place. I can replace it if it’s necessary - but given where I’m at now; it’ll be a delicate surgical operation for me, lol.

Dumble initially used a 2 position until a customer worked out that balancing the switch gave you PAB. I have a 3 position on some amps but I honestly don't use it as there is a switch on the back as well as a pedal.

[Raoul Duke]

Ahh, ok - I think I understand. The 2 position will work for J/R, but no PAB from the front; but otherwise is fine as wired in the original 102 layout?

I appreciate both your quick responses guys, thanks!

[martin manning]

What you need is to have both rear panel switches grounding their respective relay coils when switched to "manual," and connecting the relay coil lead to the footswitch jack when set to "pedal." They should both be wired like the OD rear panel switch in the 102 layout. See modified 102 layout snip below. Note for toggle switches the pin connections are flipped vertically.

[Raoul Duke]

I don’t know why I’m not picking this up quicker; seems like a simple thing. Had a few head injuries over the years, maybe that’s it?

Anyhoo, what you’re saying is to wire the pedal switches as you’ve indicated in the 102 snip then Martin? And if so, is the black line under the caps on the bottom row of switch pins connecting pins 6, 3, and 6 running under the caps? Also, would the cathode of the LEDs both go to pin 1 on each switch then?

Apologies for all this. I really am frustrated with my inability to grasp this and feel like I’m probably frustrating you all as well.

[martin manning]

...wire the pedal switches as you’ve indicated in the 102 snip then Martin?

The schematic snip above is from #124, but wire your footswitch just like the part at the bottom showing the LED's. Note when the switches are closed they connect the LED cathodes to ground; you have +12 coming in on two of the jack pins.

...is the black line under the caps on the bottom row of switch pins connecting pins 6, 3, and 6 running under the caps?

Yes. This refers to the #102 layout snip I modified. The relay coil leads are connected to the poles (center lugs), one side of both switches is ground (black wire that does go under the caps), and the other sides go to the footswitch jack. You will be able to get PAB and OD using either the rear chassis switches or the footswitch. If you replace your R/J switch with an On-Off-On, you could get PAB from the front panel as well.

Below is the exact schematic you need.

[Raoul Duke]

Thanks Martin, I appreciate the visuals and have tried to understand the schematic (still am). I’ve referenced a few videos and web pages, but my understanding and interpretive skills are still evolving. Based on what I think I see:

LED cathodes go to pins 1 and 4 (determined by orienting by the caps). I think the pins are the connections shown by the red blocks at junctions?

But then I look at the snip…

I think what I get out of this is that the LED cathodes go to pins 2 and 5 on each switch and the plug’s 2 and 4 connections stay as shown in the 124 snip - coming from pin 4 of both switches?

I know my lack of understanding schematics is the problem. Trying to cram that right now, but you guys are the only sounding boards I have - which leads me to my stupid questions. Ugh!

[martin manning]

Yea, schematic reading is a skill, as is drawing an easily understood schematic. Maybe this helps? The other side is the same.

[Raoul Duke]

Tremendously! Thanks Martin!
Just giving the switch some context made all the difference. I truly appreciate your patience and willingness to help others learn.

Seeing this is both a relief and somewhat embarrassing, lol.

Onward…

Got myself a 40w clear appliance bulb today and will begin setting up tomorrow for the power amp testing hopefully this weekend

[Raoul Duke]

Had a couple of minutes to tinker this AM and this is what I have so far. Before moving to the other side, I wanted to see if I’m on the right track.

IMG_0172.jpeg

Also got the heater wires up to the PI in:

IMG_0173.jpeg

[martin manning]

Move the LED lead to the center switch contacts. I has to be on the same side as the relay coil lead so that when the switch closes it connects both the LED cathode and the relay coil lead to ground. The cap goes across the switch contacts, so it's correct as you have it.

Do you have a signal source to feed into the power amp?

[Raoul Duke]

Thanks, I’ll move the LED cathode. Do I leave the pin 4 lead where it is so that they’re on the same switch pin, or does either pole pin work for either connection? If I’m understanding correctly, I think either will work - just testing myself, lol.

I don’t have a signal source as in a bench-top device; what sort of signal coming in will work?

[martin manning]

Thanks, I’ll move the LED cathode. Do I leave the pin 4 lead where it is so that they’re on the same switch pin, or does either pole pin work for either connection? If I’m understanding correctly, I think either will work - just testing myself, lol.

Either one works. You are paralleling two switches.

I don’t have a signal source as in a bench-top device; what sort of signal coming in will work

A phone app and a cheap Bluetooth adapter will work. Not strictly necessary, but you could use that to set the PI trimmer.

[ijedouglas]

A phone app and a cheap Bluetooth adapter will work. Not strictly necessary, but you could use that to set the PI trimmer.

Martin, are you suggesting to set the PI trimmer before wiring up the rest of the amp?