Wireless Set No. 52 Canadian - Project

[David Dunlop]

Cleanup and inspection of the Remote Receiver was completed this week, short of currently not yet being able to test any of the valves in it. So some may be weak or dead. Fingers crossed in that regard for the time being.

Before anything else, I cleaned the Connector Plug No. 1, checked it visually for anything obvious and hooked it up to the Remote Supply to test the continuity of it with the supply. Output was perfect so next step was connection of the Connector Plug to the Remote Receiver and turn the supply on.

The only thing that happened was a soft, steady hum from the speaker that was appropriately interrupted when the selector switch was toggled between 'SPEAKER" and "PHONES". No Indicator Lamp, or Meter readings and no response from the Calibrator when turned on. Supply 'off' and think for a bit.

I then pulled out my tired looking parts receiver and decided to hook it up to the supply after a quick inspection and see what it did when activated. How sweet. When the supply was turned on the Receiver On lamp lit and the HT reading on the Meter jumped to 160 and slowly dropped to around the 155 mark. Switched on the calibrator and it's lamp lit. And the meter readout dropped another couple of needle widths closer to 150 Volts.

That got me thinking the problem with the Remote Receiver must be close to the Input Socket since the inactivity of the set was so comprehensive. I could not see anything out of the ordinary around the socket assembly, but did notice that the three countersunk, slot head screws that mount the socket assembly to the chassis all had damaged slots, strongly suggesting somebody had it off at one time. So I pulled the screws and took a look behind the assembly. First thing I noticed was an unconnected wire waving at me. A careful check of all terminals at the back of the socket compared to those on the working backup supply, confirmed where the wire had broken loose from. Out came the jumper cables, as per the attached photo.

With ground for the socket assembly jumpered, along with the broken connection, I turned the Remote Supply back on. Happy Dance! The Meter came to life with the correct HT reading, the receiver lamp lit and so did the calibrator lamp when activated.

Seems a soldering project is in store this afternoon!

David

[David Dunlop]

While I think of it, has anyone had experience disassembling the large Bakelite Connector Sockets on this equipment? It is hanging down with the supply plug attached to it in the last photo, but a better view is in Post #28 of this thread.

One of the contacts had been broken off on this Remote Receiver, and there is a large relay mounted on the back of it that would have to be unscrewed. I am curious if replacing the broken contact would be a purely mechanical process or if a soldering iron is required. A large, heavy duty terminal strip runs along the inside lower end of the socket that likely feeds to the individual contacts. My guess is these contacts are probably mounted via screws to their respective terminals.

David

[Chris Suslowicz]

Originally Posted by David Dunlop

While I think of it, has anyone had experience disassembling the large Bakelite Connector Sockets on this equipment? It is hanging down with the supply plug attached to it in the last photo, but a better view is in Post #28 of this thread.

One of the contacts had been broken off on this Remote Receiver, and there is a large relay mounted on the back of it that would have to be unscrewed. I am curious if replacing the broken contact would be a purely mechanical process or if a soldering iron is required. A large, heavy duty terminal strip runs along the inside lower end of the socket that likely feeds to the individual contacts. My guess is these contacts are probably mounted via screws to their respective terminals.

David

It's easier than you think (probably). All the connectors are identical bakelite mouldings and the contacts are fitted 'as required'. the connector body is attached to the chassis by two screws from the rear (between the rows of contacts) which go into threaded brass inserts in the bakelite moulding, and the contacts are fitted from the front with a lock washer, tag, and nut on the rear, then the nut is sealed with varnish to prevent it working loose. (Do NOT try unscrewing the contact from the front, you will just deform the contact and possibly shear the screw head off.) The 'terminals' are actually tags; short straight ones for the contacts on the bottom row, and longer 'L' shaped ones for the top row. They fit into grooves in the bakelite moulding so that they cannot move sideways. You'll need a thin, broad-bladed screwdriver for the contact side, and a box spanner or nut driver for the terminal side. The screw slot is in line with the slot in the contact and the screwdriver is used to hold it in place while you attack the nut on the back. I'd advise softening the varnish with something (Acetone?) before attempting to undo the nut. (Of course, if the contact is missing because the screw is broken, you may just be able to withdraw the broken screw with nut attached and fit a new contact fairly easily.)

I have your valve holders / tube sockets and will include a scrap WS52 connector that you can use for parts. Hopefully this week if I can get to the Post Office.

Chris.

[David Dunlop]

Thanks for that, Chris. Let me know the postage and I will send it off to you.

The spare connector may come in very handy. The broken connection behind the connector socket assembly was one of the Aerial Circuit Relay terminals and that relay is inactive normally in the Remote Receiver. Good to now have it reconnected though and the free wire out of any future harms way all the same.

However, (Interesting how that word can pop up so often in restoration work), once the connector socket assembly was remounted to the chassis and power reapplied, I no longer have +12 V anywhere in the system and no +150 V showing on HT Mode on the meter. Every valve is stone cold inactive.

I switched the Remote Supply to my backup receiver and that receiver lit up straight away. All voltages normal and the meter shows about half the valves with normal readings, the remainder with nil readout. While hooked up, I took readings from the terminal strips on the back of the connector socket. The HT was 155.5 V with the meter showing spot on 150 V. The LT reading at the connector terminal was 2.39 V. Struck me as a bit low but all items downstream from there on the LT side were responding correctly.

Back to the Remote Receiver chassis to check the same two connector socket voltage values. The HT terminal came in at 218.5 V. This is very close to the raw output HT from the Remote Supply. The LT reading was 0.75 V.

What initially comes to mind is a short in the system and with the missing contact on the connector socket, I am wondering if the screw stub and/or nut inside may finally have broken free and moved into contact with internal circuits. I briefly had a working system when I first jumpered the broken relay wire behind the connector socket assembly. Maybe all the jostling about of the socket assembly while resoldering bumped the broken hardware free inside to run amok.

Sigh!

David

[Chris Suslowicz]

Originally Posted by David Dunlop

However, (Interesting how that word can pop up so often in restoration work), once the connector socket assembly was remounted to the chassis and power reapplied, I no longer have +12 V anywhere in the system and no +150 V showing on HT Mode on the meter. Every valve is stone cold inactive.

I switched the Remote Supply to my backup receiver and that receiver lit up straight away. All voltages normal and the meter shows about half the valves with normal readings, the remainder with nil readout. While hooked up, I took readings from the terminal strips on the back of the connector socket. The HT was 155.5 V with the meter showing spot on 150 V. The LT reading at the connector terminal was 2.39 V. Struck me as a bit low but all items downstream from there on the LT side were responding correctly.

Back to the Remote Receiver chassis to check the same two connector socket voltage values. The HT terminal came in at 218.5 V. This is very close to the raw output HT from the Remote Supply. The LT reading was 0.75 V.

What initially comes to mind is a short in the system and with the missing contact on the connector socket, I am wondering if the screw stub and/or nut inside may finally have broken free and moved into contact with internal circuits. I briefly had a working system when I first jumpered the broken relay wire behind the connector socket assembly. Maybe all the jostling about of the socket assembly while resoldering bumped the broken hardware free inside to run amok.

Sigh!

David

What you've got there is no heater supply, so there's no load on the HT. The very low heater voltage could be due to a short circuit (loose bit of metal in the back of the connector, shorting something to ground), or to a high resistance (dry) soldered joint in the LT circuit.

You could remove all the valves and measure the resistance between +12V and chassis - with no valves fitted it should be very high resistance (or open circuit).

If it is a short circuit, don't risk the power supply by running it for more than a few seconds - I don't think there are any fuses in the LT circuit, and it will overload the transformer.

Chris.

[David Dunlop]

Hi Chris. I initially thought a short might have been in one of the AF Amp valves, so pulled them to see what happened. Nothing, so decided to pull all of them with no ultimate change. That had me leaning towards the absence of B+ creating the inactive valves, resulting in the HT electrons with nothing meaningful to do. Thanks for the confirmation I was on the right track.

After you mentioned it, I realized I had checked the 12 V terminal to chassis and got a very high value. My brain must have been in ‘volts mode’ and did not make the connection to the fact that particular test had been resistance related, and what the result actually meant.

I’m hoping that a disassembly of the connector socket will reveal loose hardware bits floating about inside, and solve the problem.

A previous owner of this Remote Receiver had drilled holes in the rear of the case to mount a modern Coax Aerial Socket. Have since discovered this was done with liberal application of cutting oil and with the receiver chassis still in place. The bottom back edge of the case was wet with oil and metal chips stuck in it. Spent a while cleaning it all up and also found the same crude sitting in the bottom lip of the rear chassis. Visually, the lower chassis floor looked OK but when I pulled the V1G and V1H valves, I found a sweat of oil between the sockets and valve bases. More cleaning done there as a result and another reinspection.

David

[David Dunlop]

Thought I would take a break here to poll the collective wisdom of the MLU Group.

I will start by referencing back to Page 2 of this thread, Post #46, Photo 3. This is an interior shot of the ZE-11 Remote Supply cover. Of interest here is the nature of the interior finish that is visible.

My first thought was this finish was just another metallic looking paint, although what stood out with it was the extremely fine metallic powder that must have been used to make it. it does not look at all like the typical aluminum finish paints available today. Curiosity got the better of me eventually and I tested the surface of the finish with a multimeter and was very surprised to see how conductive it was. A closer inspection of the Remote Supply revealed the entire cover assembly AND the base assembly had this coating under the paint.

A closer look at the Remote Receiver Case revealed it too had a complete coating of this finish on it, covering the entire finished assembly, with the exception of the Grounding Post Screw on the lower rear right side. The finish paint was then applied to the case, reaching into it only two inches from the leading edge of the case. I have yet to see one in person, but strongly suspect the entire basic, sheet metal case assembly of the Carrier No. 4 for the 52-Set is also finished in this coating. The heavier metal parts of the Carrier Assembly, possibly not.

I am pretty certain this is an electroplated finish and have narrowed the possibilities down to three metals: cadmium, satin nickel and zinc. I am presently leaning towards the satin nickel finish. From what I have seen of 75 year old cadmium and zinc plated items, somewhere, to some degree, one can find traces of humidity induced oxidation of the metal. The finish on these 52-Set items is pristine.

Once the dust settles with the new school term at the University of Manitoba, I would like to take the Remote Supply cover over to their Chemistry Department and see if they might have a none destructive means of testing this finish to determine what metal it is. I will need to know since several holes drilled into the back of my Remote Receiver case will need to be repaired and I would like to then have the case replated to completely restore the original look before painting.

I have run across a few references to satin nickel plating being used on wartime electronic items intended for navy use and shiny nickel pated finishes show up quite regularly on valve covers in army equipment. Has anyone encountered written references to the use of a satin nickel electroplating on components of wartime wireless gear?

David