Anyone familiar with AA Electronics Solo 100 board?

[GKWallace]

I'm probably in a little over my head, YOLO.
The layout attached shows the 3.15v AC1 and AC2 from the Power. Does that go to the terminals on the DC heater mod covered by the arrows indicating out?
Neither the schematics or the layout show how this should be wired.
It seems there should be a terminal strip somewhere to split the AC1/AC2 to go to the different sides of the chassis to the tubes.

If someone would be so kind as to draw this up I'd be forever grateful.
 

[mresistor]

Hi,  Have you visited the AA Eectronics website created and account then signed in  and then visited the resources page  and then scrolled down to look at the resources available for that particular PCB amp board?


If so you would see some great very helpful information. https://www.aaelectronicspcb.com/resources  Do you have that dc filaments mod PCB board from them?
If not look at their schematic and then devise your own board and a layout of their circuit. 


The circuit is below   I snipped it out for you    which will help you to make sense of how it fits into the entire schematic.  Or you can just look at your layout above and probably make sense of it.

A & B in the snippet go to AC1 and AC2 on the power transformer because if you use the DC heater mod for the V! V2 filaments they would then not connect to the 6.3vac filament line. Look at the schematic and you'll see that.

[GKWallace]

Hi,  Have you visited the AA Eectronics website created and account then signed in  and then visited the resources page  and then scrolled down to look at the resources available for that particular PCB amp board?


If so you would see some great very helpful information. https://www.aaelectronicspcb.com/resources  Do you have that dc filaments mod PCB board from them?
If not look at their schematic and then devise your own board and a layout of their circuit. 


The circuit is below   I snipped it out for you    which will help you to make sense of how it fits into the entire schematic.

I have been there and have all the documentation. Some other people on their forum have had the same question, but no answers.
I just found a post over at pedapcb.com and the builder had the same issue, but got it figured out with the help of Rob at C3 amps.
I'll probably reach out to them since they've been through this before.

[mresistor]

Sounds good  I was trying to find out how much you had already dug into this and what documentation you already had.  I noticed on the AA website that they don't sell the DC filaments Mod pcb.  My thought was why?


Are you in the UK?

[GKWallace]

Sounds good  I was trying to find out how much you had already dug into this and what documentation you already had.  I noticed on the AA website that they don't sell the DC filaments Mod pcb.  My thought was why?


Are you in the UK?

No. Pasadena, CA
After looking at it a while longer I have new questions....
The DC mod wiring makes sense, but what about the 6 other tubes?
I know how I'd wire it without the mod, I'd put in a terminal strip and split the 2 -3v in different directions, to the preamp and the power tubes or just run it in a circle in a series.

[mresistor]

The way I look at it..   Go from AC1 and AC2 3.15VAC to a terminal strip.  Then from that terminal strip take one wire pair to the DC Filaments Mod to V1 and V2. Then from those same two terminals wire V3 - however many more tubes there are just like you would wire up any other amp. IE a 6.3VAC filament string.  The DC Mod for V1 and V2 will be in parallel with the other filament string to the other tubes.

You'll have to get creative on how to physically mount the DC Fil Mod board.

[mresistor]

You do realize the AC heaters are elevated as shown here on the far right? Read the note about the 6.3VAC center tap usage if using the elevation.  The option to elevate the AC heaters is up to you   you don't have to elevate them. 

[GKWallace]

All that makes complete sense. I was considering just wiring it all normally, but I hate when I give up on trying to understand something. (kinda the whole point of doing this advanced art project)

Thanks so much for your help.

[mresistor]

I think I would do one or the other.


1. Elevate the entire 6.3VAC filament line 


2. Use the DC Filament mod for V1 and V2 only all other tubes on 6.3VAC.


Question is    if using the DC Filament mod for V1 and V2 only do we still use the PT filament winding center tap to ground?


I read this and Merlin says not to ground in two places.  Either on one side a bridge or the other  not both.   (bottom of page) https://www.valvewizard.co.uk/heater.html

[GKWallace]

Question is    if using the DC Filament mod for V1 and V2 only do we still use the PT filament winding center tap to ground?

That's where I am now. Or maybe a faux ground on the others?

[mresistor]

The ground on this one is past two filter caps and inbetween two other caps which causes me to be not sure.


Hopefully someone else will be along to shine a light.

[Willabe]

mresistor asked me to look at this post. I have been watching this.

Not to discourage you but this amp has over 200 parts in the BOM list. And a heater dcv preamp option for V1 and V2.

Have you built any amps before? This is is a very advanced build for anyone to attempt.

This is a very high gain amp? That's why they have the dcv preamp heater option. Grounding is going on the complicated side. With all that circuitry it will not be easy especially if your not experienced with good grounding schems.

There is a sub groups favorite that tubenit gathered and posted, look in there. If you ground a dcv heater supply wrong you can take out the PT.

[GKWallace]

mresistor asked me to look at this post. I have been watching this.

Not to discourage you but this amp has over 200 parts in the BOM list. And a heater dcv preamp option for V1 and V2.

Have you built any amps before? This is is a very advanced build for anyone to attempt.

This is a very high gain amp? That's why they have the dcv preamp heater option. Grounding is going on the complicated side. With all that circuitry it will not be easy especially if your not experienced with good grounding schems.

There is a sub groups favorite that tubenit gathered and posted, look in there. If you ground a dcv heater supply wrong you can take out the PT.

I appreciate your concern and I understand it's a complex amp. And you are correct, I may be in over my head.
Again you are correct with the grounding, that's what's got me confused. That and the DC heater mod.

I have built a little tweed and then a JTM45. I don't even have any parts yet, I just ordered my board. That's why I'm here now, to learn everything I can and fully understand what's what. If it wasn't hard I wouldn't do it.

Thanks for chiming in and helping and any other advice is much appreciated.
It's nice to have strangers that actual care if you smoke your amp or yourself.

[Willabe]

I found it, it's top of the list in Archives of favorite topics. Relay circuits and grounding. Thank you tubenit. 

https://el34world.com/Forum/index.php?topic=14348.0

[GKWallace]

I'll do as suggested.
One big question is....
If the center tap is already used in the DC mod is it a reference ground and if so, I've read that having the other non DC heaters grounded is a bad thing, no 2 grounds.

[Willabe]

There is a sub groups favorite that tubenit gathered and posted, look in there. If you ground a dcv heater supply wrong you can take out the PT.

I found and posted the link for you.

It's a long thread, but it has the information you want on how to ground dcv power supplies. Their using it to power a 5v relay, but you can use it to power tube heaters.

Do the work for yourself. 

And in it, it shows the PCB board our host Doug sells for a 6.3 heater to 5dcv. 

[Willabe]

Doug's board could be used with a 6dcv regulator if the board you have doesn't have it.

12A_7 tubes heater supplies can/need to be +/- 10%. so if you can get 5.67dcv.

6.3 x .1 = .63  >  6.3 - .63 = 5.67

I wouldn't trust my math. 

6.3 x 1.4 = 8.82 - 1.4 = 7.42 unloaded, you lose a little from the diode drops, ~1.4v. (?) (and the smoothing cap charging) so it has some room for the regulator, they have low drop out 6v regs.

[acheld]

Couple of comments:

I bought this board awhile back, and am just now thinking of building a low power SLO (eg, with EL-84's in the output section).

It is by far the most complicated board Andrea sells, with options for both elevated and DC heater supply.  It's complicated enough that I recommend drawing your heater schematic with your options on top of the published schematic, and then correlating that with the board layout.   

You can print the schematic and layout in 11x17 format for about $1 per page via Fedex -- the enlarged format makes it much easier to see and follow, especially for a boomer like me with bifocals (but really, anyone).

There have been several folks who had trouble understanding the heater schematics -- you are not alone, and frankly I plan to spend some time going over this in the next month or so, just so I am sure what I am doing.

As always, 1 ground in the heater supply = bliss, 2 or more grounds =HUMM. 

[GKWallace]

I have just figured that out. Neither the schematic nor the layout shows an elevated heater AND the DC mod. Most confusing to me and it was so simple, The arrows on the board show AC1 and AC2 coming off the board. In reality it is AC1 and AC2 coming from the transformer, through the bottom holes and onto the board. That's what confused me and started this whole mess.