Wireless Set No. 52 Canadian - Project

[David Dunlop]

Back to this portion of the project once more, to get a couple of things done.

The first will be a close inspection of the surviving wiring inside the switchboard to determine what is still factory correct, and why has been reworked for whatever reason. Fortunately, this task got a lot easier with the help of two members of this forum who took the time to send me some very good photographs of the original wiring inside their Switchboard, Charging No. 5C Canadians for me to reference.

If the two additional pairs of input terminals were not present on this Mk I Switchboard, the rest of the terminals and switches are identical between the No. 5C and No. 5C Mk I Cdn versions of this switchboard. How the additional two terminal sets were actually wired in is not currently known to me, and un til it is, I am not going to mess with them, so my intent at this point is to just replicate what I know to be correct and workable. If and when I can obtain photos of the original internal wiring of an actual Mk I switchboard, or circuit diagram for same, I will go back in and finish this task quite happily.

The first requirement t was to get a supply of solid copper 10 Gauge wire in red and black loom to fabricate the missing wiring from. It took few days for me to remember I had purchased a spool of 10/3 copper wire for some household work a number of years ago. Took a little longer to recall where the heck I put it, and that got real embarrassing when it turned out to be on an open bottom shelf of a cabinet about 15 feet from my work table...in plain sight.

From initial inspection, there looked like 12 wires were either missing, or looked suspect in where they were installed. From the photos I received from our members, the longest wire runs were just a stink over 20 inches, so I decided to cut five 2-foot sections from what turned out to be a 75 metre spool of the 10/3 cable I had on hand. I had forgotten just how challenging it is to unwind the stuff from tightly wound spool and cut it, even with a good pair of shears.

Once the pieces were cut, I had to split open the wire plastic loom to expose the red, black, white and bare copper ground wires and remove them. They are all held together in a rather loose twist, so the next step was extracting the required red and black wires and leaving the white and bare copper for future considerations.

As you can see, these wires have quite a few twists and curves to them once freed up and I needed them to be as close to straight as possible to blend in with the surviving originals. They are also a heck of a lot easier to handle and work with when as straight as possible. I got the last of that work done this afternoon. It took a small bench rise with padded jaws, and some followup palm rolling on a thin dense carpet to get each piece to where I liked it, but I am now ready to open up the back of the switchboard once more and dive into its wiring restoration.


David

[Chris Suslowicz]

Um... hold fire for a bit. Later today (it's 04:00 here) I will drag my Switchboard, Charging, No.5 out of the shed and photograph both sides, plus draw out the wiring diagram and the switching "truth table" and measure the wiring.

It's not the same as your switchboard, but some of the basic wiring should be the same and you may be able to derive the connections for the missing terminals.

(I still think yours is an early Air Ministry version that bears little resemblance to the WS52 or WS19HP (Canadian) switchboard. Mine is intended for permanent installation in a Wireless Truck and I suspect there was a demountable switchboard issued with the "Truck & Ground Station" kit.)

Right now I need sleep.

Good Morning!

Chris (G8KGS)

[David Dunlop]

Thanks, Chris and Sweet Dreams.

I pulled the plywood back cover off the switchboard this morning and started a detailed visual. There are nine factory original, lacquered, cloth loomed wires surviving, all related to the INTERNAL LIGHTING Switch on the upper right of the switchboard, and the BATT, No. 1 ON CHARGE FROM Switch directly below it. Only one is still correctly installed.

The bank of input terminals down the right side of the switchboard all have red, positive leads fitted to negative terminals and black negative leads fitted to positive leads and when I compare to the circuit diagram, not even the correct input terminal pairs have been connected correctly.

The INTERNAL LIGHTING Switch has absolutely nothing to do with the 12-Volt OUTPUT TO WIRELESS Terminals in the centre of the switchboard, yet is the switch the leads for these two terminals come from. Have yet to trace where that mystery circuit ends up.

In addition to this major issue, I can see where at least two negative leads are no longer in their original factory positions and have been refitted to the switches with great creative licence and likely a high risk factor if any significant DC Power was ever applied to this switchboard anywhere.

On the positive side, however, speaking visually, I took advantage of the time looking at the wiring to also map out the terminals on the backs of the four switches for easier identification and cross reference to the circuit diagram. I sketched the layout of the terminals and posted a photo of same below. The identification codes are stamped into the porcelain by each terminal. The three across the bottom are in small, near square, depressions. The three across the top are noticeably larger, more rectangular depressions.

Be interesting to compare how these AH&H Switches in Canadian Switchboards compare in layout and coding to their British counterparts which I recall might have been made by "Arrow".


David

[Chris Suslowicz]

Originally Posted by David Dunlop

The bank of input terminals down the right side of the switchboard all have red, positive leads fitted to negative terminals and black negative leads fitted to positive leads and when I compare to the circuit diagram, not even the correct input terminal pairs have been connected correctly. David

Idle thought: was it wired/rewired by a German?

(The German standard for DC wiring used Red for Earth and Black for Power, based on the original telephone and telegraph polarity where the signal wire in a Central Battery system was supplied with negative voltage to remove the risk of electrolytic corrosion, and the common Earth used a red (or brown) insulator on the top of each pole, connected to a substantial earth electrode that wouldn't be bothered by a bit of corrosion.)

The magic phrase is "Let the cat out of the bag at the CAThode" - metal ions have a positive charge so are attracted to the negative electrode, so a ground current wouldn't strip metal from the signalling wire, only the "earth return" that was much easier to replace. (Also the principle of "Cathodic Protection" on ships: zinc or magnesium electrodes are higher in the electrochemical series than iron or copper (Let alone Lead!), so will always be positive with respect to the actual vessel and will be preferentially dissolved.)

Galvanized iron (e.g. wriggly tin roofing) is the same principle, and you have to lose a LOT of the zinc protective coating before the exposed steel begins to rust. Tin cans have the opposite problem: Tin is lower than Iron, so a scratch through the very thin tin layer will cause the can to rust very rapidly if wet.

Rhode & Schwartze circuit diagrams carried warnings that Red was Negative and Black was Positive to prevent REME blowing the kit up by connecting the power supply backwards when repairing stuff.

Best,
Chris.

[David Dunlop]

Hello Chris.

Thanks for the trip down Memory Lane. Somewhere, ages ago. I ran across that information and mentally misplaced it. My first thought was somebody colour blind had been mucking about. When I put the wiring to a continuity test, nothing useful was going anywhere, so I was quite pleased to pull it all out.

Most of the wires had been reworked from wherever they had originally been installed but a week of staring at the wiring photos I have on hand, and studying all the bumps and bends on the wires got all but one of them back in their original spots The last, shortest, black wire, I now have a strong hunch about but a little more thinking is needed.

In the attached photo, six of the wires have been put back on the two switch backs on the left, and two more are roughed in on the lower right switch back. The really short black wire still sits on the bench immediately left of the switchboard. The only things I know about it at the moment are which ends went on the switch and terminal post and the orientation of the end loops when in place.

I also spent two days disassembling the two larger, central terminal posts for the Wireless Set. The Positive one of them was a half inch too far forward on the front side and the back ends of both had been so heavily varnished the brass nuts were frozen. I had to take the front end apart to remove it and soak it in solent for a day to get the nuts loose enough to work them free. Wire brushed a bunch of goopy varnish off the studs and then worked the nuts back and forth along the stud for about 30 minutes with light oil to get them all back to normal. Then it was just a matter of reinstalling them to get 1.25 inches of stud showing on either side of the bakelite panel.

Incidentally, all this wiring is essentially 10-guage, silvered, solid copper wire with either a black, or red cotton sleeve, loosely slipped over the cut pieces. In the photos I have available, most of the switchboard wiring is this original stuff, but about one quarter of the wiring has been replaced with more modern red, or black, plastic loomed, 10-guage solid copper wire. So the missing pieces of wiring I have to make up replacements for, will look appropriate when done.


David

[Chris Suslowicz]

Originally Posted by David Dunlop

Incidentally, all this wiring is essentially 10-guage, silvered, solid copper wire with either a black, or red cotton sleeve, loosely slipped over the cut pieces.

It will be "Tinned copper wire" Mouser sell it as "Busbar Wire" but you don't want to know the price!

On the other hand, there's the "Scientific Wire Company" that supplies 500gram or 1kilogram quantities in a variety of sizes, see:

https://www.scientificwire.com/acatalog/tc-wire.html

The varnished cotton sleeving ("Systoflex") seems to have disappeared decades ago, to be replaced by synthetics.

In the photos I have available, most of the switchboard wiring is this original stuff, but about one quarter of the wiring has been replaced with more modern red, or black, plastic loomed, 10-gauge solid copper wire. So the missing pieces of wiring I have to make up replacements for, will look appropriate when done.

I've just had an unissued British switchboard delivered (bought on eBay) and the wire is all plastic sleeved (no dates on it). It was also extremely heavy, which raised my suspicions... I thought the switchboard was a plastic laminate (there was a lunatic in Italy trying to sell a scrapped, dug up, one for ridiculous money, it had a chunk broken off one corner and looked as though it had delaminated while in the ground), but this new one feels more like a paving slab, and I think it's actually _slate_! That might explain why the lettering is stencilled rather than being engraved and wax filled.

I suspect the slots in the top and bottom bearers are for airflow. (To allow any heat to dissipate and also to prevent condensation that might cause corrosion of the wiring and switches.)

Anyway, I now have one with four mounting screws, and a second one with the brackets and studs, etc. in a cloth bag that make it demountable.

Best regards,
Chris.

[David Dunlop]

Congrats on the new switchboard, Chris.

After a couple of days trying to figure out where that short black lead had originally come from in the switchboard wiring, I was about ready to set it aside and move on when I remembered I had just been looking at all the standard Switchboard, Charging No. 5C possibilities. This switchboard was actually a No. 5C Mk I, with two additional sets of Battery terminals, so I took a closer look at the two negative Terminal Posts.

From the back of the switchboard, the additional negative terminal on the right hand side was too far away from any negative terminal on the lower switch, that it could logically tie into. Likewise, the upper switch. On the left side, things were suddenly looking up big time. With the curve of the wire for engaging the new negative battery terminal, properly oriented on the terminal stud, the smaller end for wrapping around a switch terminal, was properly oriented for engaging a terminal on the left side of the lower switch, and just the right length to engage the same switch terminal as the standard negative battery terminal wire was connected to already.

The current school of thought for the creation of the Switchboard, Charging No. 5C Mk I Cdn is that it was developed to help solve the thirst for Amps that the 52- Set and 19-Set HP had, in comparison to the basic 19-Set. The easiest way to do that is to connect a second set of wireless batteries in parallel with the original set of batteries. This preserves the critical 12 Volts DC in the system for providing the required Low Tension feed to the wireless set. The big gain, however, is that instead of say just 175 Amp Hours from the original set of wireless batteries, the available Amperage doubles from 175 to 350. The higher the available amperage, the longer the wireless set can run before the batteries need recharging. What I am unsure of at this point, however, is how lone would it take for the standard 300 Watt Chorehorse to fully recharge two sets of wireless batteries connected in parallel, and could it handle the load of doing so easily?

In the attached photo, the top left terminal is the original N0. 5C Negative Battery Terminal, and the inboard is the new addition on the No. 5C Mk I switchboard, paralleled to the same switch terminal.



David

[David Dunlop]

The two wires that were roughed into place in Post #1265 above have now been installed onto the lower right switch.With all the surviving original wires accounted for, I can start adding in new replacements for the missing wires with plastic loomed 10-guage solid copper wire.



David

[Chris Suslowicz]

Originally Posted by David Dunlop

Congrats on the new switchboard, Chris.

Thanks I need to trace the switch paths and match that with the front panel markings. The odd part is that they appear to have used "inactive" switch terminals as anchor points, because the upper switches have three "OFF" positions and only a single "ON" marking.

Your switchboard (despite claiming to be a Mk.1) is later than, and different to both of mine. It also doesn't match the one that Guy (in Belgium) has got for his wireless truck. I'm convinced yours is (or was) an Air Ministry "special" that has been re-purposed before being sold off and gutted/rewired.

After a couple of days trying to figure out where that short black lead had originally come from in the switchboard wiring, I was about ready to set it aside and move on when I remembered I had just been looking at all the standard Switchboard, Charging No. 5C possibilities. This switchboard was actually a No. 5C Mk I, with two additional sets of Battery terminals, so I took a closer look at the two negative Terminal Posts.

Are they Battery terminals though? Starting at the top, you have:

*. *
12V+. Batt
BATT No.1. No.1
12V- CHARGE
* *

*
+
CHARGER
No.1
-
*

...and the equivalent terminals for BATTERY No.2, CHARGER No.2 and INTERIOR LIGHTING on the opposite side of the board.

I think the additional terminals were for the connection of an AC Mains powered trickle (or float) charger to maintain the batteries when not in use in the field and an AC supply was available. (To avoid the need to run the charging set(s), saving fuel and reducing noise, etc.)

From the back of the switchboard, the additional negative terminal on the right hand side was too far away from any negative terminal on the lower switch, that it could logically tie into. Likewise, the upper switch. On the left side, things were suddenly looking up big time. With the curve of the wire for engaging the new negative battery terminal, properly oriented on the terminal stud, the smaller end for wrapping around a switch terminal, was properly oriented for engaging a terminal on the left side of the lower switch, and just the right length to engage the same switch terminal as the standard negative battery terminal wire was connected to already.

The current school of thought for the creation of the Switchboard, Charging No. 5C Mk I Cdn is that it was developed to help solve the thirst for Amps that the 52- Set and 19-Set HP had, in comparison to the basic 19-Set.

I'll (politely) disagree on that. The Switchboard 5C that Guy has appears to have the same stores code (with CAN/BR/ inserted because it's Canadian manufactured), and was issued with the WS19 Truck & Ground Station as well as the WS52 - it's the same switchboard apart from the lettering changes (Vehicle Dynamo and Power Unit to Charger No.1 and Charger No.2).

I think that change was made for the WS 52 ground station which was supplied with two charging sets. (Some WW2 vehicles carried a pair because they had multiple wireless sets, e.g. command vehicles.)

The easiest way to do that is to connect a second set of wireless batteries in parallel with the original set of batteries. This preserves the critical 12 Volts DC in the system for providing the required Low Tension feed to the wireless set. The big gain, however, is that instead of say just 175 Amp Hours from the original set of wireless batteries, the available Amperage doubles from 175 to 350. The higher the available amperage, the longer the wireless set can run before the batteries need recharging. What I am unsure of at this point, however, is how lone would it take for the standard 300 Watt Chorehorse to fully recharge two sets of wireless batteries connected in parallel, and could it handle the load of doing so easily?

The WS19 was supplied with either 6 Volt 85 Amp Hour accumulators (in pairs) and a power lead with Niphan plugs that would connect them in series and to the set supply unit, or 6 volt 100/125 Amp Hour ones (with butterfly nut terminals) - Command vehicles and tanks could get 170 AH batteries (again, 6-volt units).

The WS52 (I think) got 6-volt 200 Amp Hour batteries, and a Chore Horse could recharge those in 10 hours, so not a problem - but you would need two Chore Horses to bring everything back from "flat".

"Front Line" (static) units would not have charging sets as they would give their position away, so freshly charged batteries would be delivered along with rations and ammunition on a regular basis and the discharged batteries returned to a central recharging station (with 1260 Watt (or larger) charging sets and dedicated maintenance crews).

Best regards,
Chris. (G8KGS)

[Chris Suslowicz]

F*** these web designers that delete multiple spaces so you can't draw a layout using f***ing keystrokes.

I can't be bothered to redraw it at this time of night (00:15) - use your imagination.



Chris.

[David Dunlop]

I have a 4MB photo of the Wiring Diagram for the Switchboard, Charging No. 5C Cdn I will dumb down and post tomorrow.



David

[David Dunlop]

Photo of Wiring Diagram attached for No. 5C Cdn.

Note the same switches and identifications are used on both this switchboard and the No. 5C Mk I Cdn. The switches are all 2-Position "OFF", in a vertical orientation, and 2-Position "ACTIVE CIRCUIT" horizontally. The top pair control Batteries and the lower two control Chargers. So with the exception of adding the two new pairs of Terminal Posts, the internal wiring and functionality between the two switchboards is identical.

Looking at the front panel, the left pair of new terminals have the following ID stencilled between them:

BATT
NO. I
CHARGE

The right side pair of new Terminal Posts show:

BATT
NO. 2
CHARGE


David

[David Dunlop]

A little bit more progress yesterday with both output terminals to the Wireless Set, at the centre of the switchboard now wired back into the system.


David

[David Dunlop]

Working late on a project like this is never a good idea.

This morning, I was reviewing the wiring I had done so far and discovered an 'Oops' in the system. Take a look at the vertical black jumper cable on the far left side. It is installed between the correct two switch terminals, however, for some reason, I ran it directly between said terminals and in the process passed the wire directly over the top of a terminal on the lower switch that had not yet been wired into the circuits. A quick check of the wiring photos I have on hand confirmed the original factory wire in this location actually dog-legged to the left, beyond the switches, in order to clear the backs of both the upper and lower switches. So out went last nights piece of wire and in went a corrected new one. A few more wires later and this work was done.

Out of five, two foot sections each of red and black 10-guage wire I prepped to start with, just one piece of red wire was untouched, and if I had not 'Oopsed' that one black lead I probably would have had a 2-foot spare of it left over as well.

Now all I have to do is flip the switchboard over and run a test of all the circuits and switches to see if they all perform correctly.


David