[Ron Ramirez]

Replacement PC boards for classic 1970s (and mid-late 1960s) solid state receivers makes perfect sense. When I was restoring a solid state Fisher 200-T, I could have used two replacement preamp boards - and, yes, I know now that I could have one-offs made if I wished.

PC boards for 1930s-1940s radios is not a good idea. It is best to retain the original design with point-to-point wiring.

[morzh]

Well, I could take a Ford-T, put a DOHC fuel injection motor in it....or even a hybrid one with a battery....sunroof, A/C, electric chairs, windows, and pedals' position memory in it.....and end up with a PT Cruiser.
We are talking of collectable antiques.

I understand if one lives in a 16th century house, then, yes, you probably want to be comfy, and you will put a modern HVAC, water, sever and security in there. And even TV cable. But this is about necessity.
Putting a PCB in a radio to me is not different from making that radio into a kitchen cabinet or a bar, giving it some shabby shick look. Or, better yet, gutting it and putting a Bluetooth speaker inside.

There are things that simply do not belong. Even if they can be successfully done.

[MrFixr55]

@ Morzh, Funny that you should mention gutting a vintage radio, restoring the cabinet and replacing the chassis with a Bluetooth speaker. There is someone routinely advertising on "The Bay" who does just that and sells them (successfully?) for a king's ransom!

Funny, most audio stages of AM radios are rather decent, and since many already have a "phono" or "TV" Input (or can be discretely added with little or no damage), adding an aux or Bluetooth input would be more acceptable. These mods were sometimes actually done by Radio shops in the 30s and 40s, and sometimes with kits made available by manufacturers like RCA. I think this seller probably received a lot of "feedback" ("blow-back?"), as he now offers to ship the unrestored chassis for extra shipping charges.

Agreed, that trying to add a PC Board to a 1930's radio would degrade the value. Think of all of the work that Purists go through to stuff caps, sometimes even hiding the splices in the wax resealing. In addition, adding a PC Board for most antique radios would likely either not improve or possibly degrade performance unless signal isolation was considered. Considering that we are usually talking about a 5 or 6 tube AM or AM Shortwave (less than VHF frequencies), I would not think that any gain would be realized. The average reason for use of a PCB in manufacture was to automate the manufacturing process.

[morzh]

Using PCB even back then would cut the costs a lot by eliminating the poin-to-point wiring that was, I am sure, time-consuming. And you would in essence create a pre-wired module, that only had to be connected to the power, the sp[eaker and possibly (not always) to controls.

PCB became more valuable as the technology progressed as eventually any other way of wiring became impossible (then came the microchips which are micro-PCBs of a sort).

However in old radios PCB actually would add cost. If one uses a PCB strictly as a cluster of wires then what.....every component still has to have a wire going to it. So you have almost as many wires as you had before, PLUS the PCB that interconnects them, at the same time adding the cost of itself and taking space. PCB is only effective if most components are mounted on it, not away from it.

And also, as I noted in the topic about Philco Portable record player, when I was restoring it (same as when I was tinkering with phenolic PCBs as a kid, making radios from kits), I saw lots of PCB traces unglue and separate from the laminate. Soldering of a pad only could take so many solder-desolder cycles, but even in that player, where the traces were quite wide, and Germanium transistors were soldered to them (they did not use lead-forming back then), they would by their own weight tear the traces from the board, and them the fragments of the traces would eventually crack and separate from the rest, so the electronics would cease to function. It took time for the PCBs to become reliable, and for the assembly technology build up the experience knowing what worked and what did not.

[mikethedruid]

Early PCBs did not mix well with vacuum tubes because the heat from the tubes ended up causing problems with the boards. Even when they used special long lead heat isolating sockets this did not fully solve the problem. It was not until things switched to transistor circuitry, and improved PC boards that this became less of a problem. Early PC boards were usually one sided, and used jumpers on the blank side where needed. The traces were kept as large as possible by convention to lessen the chance of the tracks loosening from the board itself. One basically just removed enough copper between the tracks to isolate them.. How do I know? PC board design was one of my specialties when I was working. I went from black puppets and traces on the mylar sheets on a light board, for one sided boards, to black puppets with red and blue trace tape on the mylar on the light board for 2 sided boards, to CAD on a PC board and 4 layer boards.

[morzh]

Mike


Back in the USSR phenolics with one-sided copper were used in 80s. When I repaired TVs, especially the early color ones, made in end of 70-s, the circuits were exactly that - 1-sided phenolics with miniature tube sockets soldered in.
The sockets obviously heated up, which resulted in two sorts of problems:

1. The one I described earlies, where the solder pad (which was not reinforced with a through flared type via) would separate and tear off, and
2. Solder around the socket's pin would become darlk grey powder (beta-tin?) that would create intermittent, and then the absence of, contact of the trace to the pin. Worse yet, whatever that was that the solder would become, would not be melted by the iron, and was hard to clean off. It had to be removed fully, then the pad scraped to the bare copper which then would needed to be tinned and re-soldered to the freshely cleaned and scraped socket's pin. Simple rubbing with iron tip, flux and solder would not work.

[Arran]

I think getting reproduction boards made for some vintage TVs, that had issues with lifting traces, would not be a bad idea, or even tube radios with the same issue. Sylvania radios, and apparently TVs as well, had rather fragile traces that would sometimes be delaminating from the PC board well away from sources of heat, same with some early transistor radios. you can get small runs of P.C boards made to spec, even on phenolic board, and the beauty of it all is that that many service manuals had full size printouts of the traces, and graphics, on the original  boards, so you could get those reproduced. I think that the idea behind using modular chassis, with plug in P.C modules, had a lot to do with turn arounds in servicing, unplug the defective module, replace it with a new or rebuilt one, and send the old one to a rebuilder, in theory a good idea, in practice maybe not?
Regards
Arran