[MrFixr55]

Hi Joseph,

Elegant!! Maybe a bit much but elegant!! Maybe not use headers but solder flags to where the pos terminals of the caps go through the board! Nonetheless, you should be proud of your design skills. The parts deserve your name! There is a lot to be said for a complete rebuild.

Consider diking off (cutting with diagonal cutters) as much wire as possible off the connection to minimize contact time between Iron and tube socket pins. I believe that Klondike has stripped and plated chassis in his unbelievably beautiful restorations.
In additio n to his other noteriety, St. Blaise, Bishop and Martyr was noted for curing issues of the ear, nose and throat. In the Roman Catholic Church, St Blaise's feast day is February 3rd. On that day, the priest will bless the throats of those who request it, using 2 candles from Candlemas (Feb 2, the Feast of the Presentation in the temple of Jesus, and the "official" end of Christmastide).

I am 3/4 Irish, 1/4 German (and can't stand beer, ale, Guinness Stout or whiskey). Irish side likely came to the US in the 1850s-1860s during the 1st potato famine. German side were vintners (Strohschnitter meant straw cutter, but they grew grapes and made wine to this day). Great Grandfather came to US in 1883 and was a carpenter. Brother has 2 toolboxes he built. Grandpa was an engraver. Dad was an aerospace engineer.

[morzh]

The document is a bit confusing, when coupled with actual datasheet:

https://suddendocs.samtec.com/productspecs/ipx1.pdf

But OK, they tested it to three times the 750V for DWV. Datasheet uses confusing terminology, for WV it says "DWV" but these are different things. If 750V were DWV, the WV would be 250V. 

Anywho. Just remember, again: this test is for connector itself. Not mounted on the PCB. A clean plastic with controlled humidity of the air will make it to pass pretty high voltages.
However your worry now is your PCB. This connector, soldered to a PCB will not withstand long-term 750V, let alone over 3kV.
So. You probably do not need to meet 750VDC as WV, as maybe 500V is short-term (a few seconds) event, that exists while the tubes are warming up, for a few seconds. Then it will go down to maybe 450V or lower for the first rectifier cap.
But you can meet 500V if you 1) use SMT version, not through-hole (and make sure the solder pads do not protrude too much inside the footprint.) 2) pot the solder side with corona dope or what they have today for electric breakdown varnishes.

Better yet, use IPBS/IPBT connectors if you have space (you should). I think they should meet the same voltages as the otehr one, but over 4mm pitch will make it much better for surface breakdown. And, again, it never hurts too pot the solder side.
And, BTW, with these you could use through-hole versions as you will still have 100 mils board distance after using 65 mil pads, which is much better.

[jrblasde]

Great idea, thanks for the feedback! You know what, I think we’re on the verge of starting a circuit board factory hosted by the Philco Phorum!

[jrblasde]

I've gone for a change in philosophy. I thought for some time about Mike's concerns and MrFixr's input about the flags. And, late last night, it dawned on me. I need to think beyond the PCB. That is, I can reduce all of this to a single disc if I mount the capacitors up and off of the PCB. In doing so, I can reduce their footprints down to only the minimum size needed for their through-hole leads.

I recreated the design with these reduced footprints. Even so, I've got a very small amount of real estate for three capacitors. Let me explain. 

   

   

The solder lugs, twist lock lugs, and capacitors are through-hole mounted. Although the diameter of the capacitor I am replacing is 1.46", I need to fit all of my connectors within this 0.86" cutout on the chassis so that nothing with a potential different than the common negative will make contact with the chassis when the PCB is mounted. This is the same constraint I had when designing the twist-lock capacitor for my 46-480 last year, but it's an even taller order in this case with three capacitors. Basically, everything except for the twist-lock connectors and possibly any other common neutral connections needs to fit within that cutout. In addition, I need to maintain minimum clearance between any components and the outline of this cutout on the chassis.

With this in mind, I reduced the two schematics into one. 

   

I then annotated the schematic, edited the footprints to reduce their size, and then paired the new footprints to their respective schematic symbols. Finally, I created the layout. In a pink or peach color (used to represent the bottom silkscreen layer), you'll see that I added the outline of the cutout on the chassis so that I could use it for measuring clearances.

   

I found that I had enough space to beef up the traces to a full millimeter. I also have enough space to establish minimum creepage and clearance distances of greater than or equal to 3mm (as measured from the edges of any two adjaent surfaces or solder pads; the centerlines are spaced even further), which satisfies the IEC 60664-1 calculations (reinserting because I was actually able to satisfy even more aggressive transient overvoltage assumptions). And, again, the capacitors wil operate normally at 250V but I am designing to an operating voltage of 450V to match the value of the component I am replacing. 

   

Finally, I added in the 3D models and took a look at it. Out of abundance of precaution, when I build this assembly I will sleeve the exposed leads between the PCB and the caps with some leftover braided fiberglass sleeving I have, rated up to 7kV that I have from when I resleeved the power transformer leads on my 46-480.

   

   

[jrblasde]

Oh, I also did some fact checking on myself! I was wrong, Mike. OSH Park now charges $5 per square inch for their standard 2-layer, 1.6mm board. However, you still get three copies of each board. It would seem that their pricing has gone up since I last ordered, but I know that electronics are all increasing in cost.

[radiorich]

Hello Joseph,
nice job on the PCb design and 3d modeling what programs did you use ?

Sincerely Richard

[jrblasde]

Good morning, Richard! I do it all in KiCad.

[morzh]

KiCad is pretty powerful for a free tool. At work I have one project done in it, by the folks from teh company we acquired some time ago.
The folks since retired but the device is there and required some updates, so I had to quickly learned the basics. I was surprised by the amount of features you get totally for free.


Joseph.
Change in philosophy is good.
Don't forget: the PCBs were design to make the assembly convenient and easy.
So, when making it, make sure you do not create any inconveniences you then have to fight by using additional insulation, potting, glueing etc when you are done.

One thing also, I can see a pin soldered from beneath goes under the front-most cap's rim. Make sure it does not come too close/touch. Yes the caps are insulated with that film (usually, not always) but I try to avoid it anyway.

PS> you've mentioned fiberglass sleeving: where do you buy it and what kind? I need some glossy brown for AK10; the old one is all cracked. And I do not want to just use regular heatshrink, it looks wrong.

[jrblasde]

Let me see where I got that. I don’t immediately recall, but let me look into it.

[jrblasde]

Found it! I got it from Antique Electronic Supply, which is now Amplified parts. They have 20 AWG and 11 AWG, available in white or black. It is the woven "spaghetti style" sleeving. THe 11 AWG is the more expensive of the two, at $0.85 per foot.

[MrFixr55]

Morzh, I saw your work, thought of "spaghetti", what we called the impregnated cloth insulation when I was a kid. Someone sold it, but I can't remember who. If I find it, I will let you know. Seems that AES is pivoting more to guitar and musical instrument amp parts.

[MrFixr55]

Sorry, did not see Joseph's post. Left a pic of the stuff on the Amplified Parts Website in your A-K 10 thread. Stuff looks pretty correct, maybe a little newer than what A-K used but certainly more correct than heat shrink.

[morzh]

I just bought som UXCELL silicon impregnated fiberglass black sleeving on Amazon. Seems OK to me. The original is dark brown, but no one sells this.

there is glossy polyolefin heatshrink too. But I decided to have fiberglass.

[morzh]

Joseph

I bought this on Amazon.

https://www.amazon.com/dp/B082KG5BY7?ref...title&th=1


It is the same only $0.46/foot.

And if you have prime, you won't have to pay shipping.

[jrblasde]

Now that’s an excellent price!