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Old 15-04-21, 18:08
David Dunlop David Dunlop is offline
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Join Date: Feb 2006
Location: Winnipeg, MB
Posts: 3,384
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Good Evening, Mike.

I too am about as far away as one could ever get from being a qualified radio tech. My entire training was a one Year Electrical Shop Class in Middle School back when Spark Gap Transmitters were still a popular means of delivering the Evening News!

You are quite right, however, that a logical troubleshooting search can be accomplished following the basic Block Diagram flow of the major circuits from the R.F. Amplifier at the Aerial end to the A.F. Amplifiers at the Loudspeaker/Headphones end. The valve and component layout within the receiver chassis follows this flow visually, in a very good manner. It is the 2nd to 4th Echelon Maintenance Manual that I find very unnerving.

I have the Wireless Set No. 19 Mk III 2nd to 4th Echelon Manual as a comparison. It is a brilliant work. It starts with a brief introduction to the set; a massive Table of Contents (the manual is some 400 plus pages) and a list of test equipment required and support items to be fabricated. Then off it goes with a very logical step-by-step analysis, with relevant disassembly instructions when and where they are needed. It is a very good manual for step-by-step work and how to do it.

By comparison for the 2nd to 4th Echelon Manual for the 52-Set, there is no list of test equipment needed and no table of contents/index at all. The first five steps in the manual are:

- Meter Calibration.
- Switch Connections (pages of exploded diagrams of switch connections).
- Cleaning the Crystal
- Dismantling the Flick Mechanism,

And then suddenly you are in:

Alignment and Specification Testing:

I.F. Alignment.

If you plod well into the manual, about two thirds, you eventually discover 12 Point to Point Voltage and Resistance Charts for the Main Set Components, providing the factory original electrical specifications for each point to point test.

I am currently replicating three of these charts for the two receivers I have available. There are a couple of more for point to point tests from the various valve pins to either switch contacts, or terminals on the 8-Pin Connectors. I hope to replicate them as well.

Time consuming, yes. But what else is there to do with Covid running amuck? Sigh! It should mean I have become very familiar with the innards of the receiver when I am done and given the electronics sections of my brain a good dusting off in the process. My hope is I end up with a set of factory standards and a set of specs from a fully working 75-year-old receiver to compare those to. That would give me an acceptable range of specs the receiver is happy to work within. Then I can see how the specs from the non-working receiver compare, so that I can narrow down exactly what has to be replaced. The more parts I can order in one shipment from a supplier these days, the better.

As long as I don’t grow cataracts in the meantime, I am laughing.

Stay safe Mike!

David
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