[morzh]

As an EE, who did design a few commercial PCBs, including an off-line power supply for India Telecom, to another EE, this is what you do: it is called "creepage and clearance". You want clearance. This is simply achieved by cutting slots in your PCB, which replaces the surface creepage by the air gap, which immediately increases the breakdown voltage.
If you build your PCBs online, they are fine with slits; you could define them as a board outline or as a long oval unplated pad.

[jrblasde]

I had read a bit about creepage, but this makes sense. Thank you!

[Chas]

https://grangeramp.com/product/multi-sec...tor-board/

$5.95

   

Search Google: [Capacitor adapter circuit board] Many other vendors and options.

Chas

[morzh]

I see, they are using slots too.

[jrblasde]

Well I’ll be darned! I had no idea that such a product existed.

[morzh]

I learned long time ago that when I think of a product, it has been made by somebody and is being sold.

In mh first house, which was 1-zone heating/AC, I thought of "what if I could have a movable thermostat with a radio connection to the base, that hooks up to the regular thermostate wiring; I would then be able to move the thermostate in the room where I want the temperature to be kept".
Next thing (it was 2006) I knew, I decided to see if it had been made by someone.
Sure enough. Not superpopular, but it did exist, and I bought it and used it for the next 9 years.

So, the lesson here: if you need something you want to make yourself, see if someone has already made it and if it is affordable. It is almost 100%.

[RodB]

I remember when I worked part time for a EE after I retired that he designed a circuit PCB that generated 1Kv and the caps that held the charge for the hv transformer primary all had slots.

[MrFixr55]

Nice job on the schematic! I hear you re the difficulty in determining wire crossing vs "node" on some reprints of the originals. Please do check the resistance readings for the output transformer, they may be incorrect. I would not expect a reading of 11.25 Ohm for the primary and 510 Ohm for a secondary that connects to a 3.2 Ohm speaker. You are doing a great job on a gargantuan project!

[jrblasde]

Indeed, let me get those measurements this evening. I copied them directly from the Philco schematic, and haven’t yet thought to verify them.

My plan is to finish with an entirely correct schematic so that we might be able to share it with anyone else who works on this model.

[jrblasde]

I had time while eating lunch to measure the resistances of the output transformer windings. I measure 450 ohms on the 6V6GT/G side and 1.4 ohms on the speaker side.

This is much closer to what the Rider’s schematic indicates. They have 500 ohms to 1 ohm.

I’ve made the update on my schematic, but I won’t reload it (yet) just for that one little change. I’ll reupload after I finish dismantling the RF chassis to get to the obscured components buried within the wafer switch. I’ll note that so far I’ve found that most components are within 10-15% of their nominal values. Even the mica capacitors are within this range. The parts catalogs specify that most of these had a 5% tolerance, so I plan on replacement.

[MrFixr55]

Hi Joseph,

I understand that you want to get all of the bugs out of the schematic before printing the last version. You do very wonderful work!

[morzh]

A suggestion: increase sizes of yuor passives. They are not well-readable.
Lool at the right upper part of the section 4: the resistor with taps is not readable at all.
I suffer from the same, but then my schematics are for myself mostly. But even there at some point I started increasing caps' and resistors' sizes.

[jrblasde]

Let me see how much I can enlarge them. I had formatted this to plot on an E sized paper, but I do realize that the blocks appear quite small on a screen.