Introduction

Article By Chris Field (The_Teleman)

Below you will find the Murphy Astra television from the early 1960s. This TV being for 405-line operation but was also an early convertible set for 625-line operation, via a module that bolted to the bottom of the TV. These modules are super rare now, see an example below in my collection.

A whole range of Astra sets were available and can be viewed here Murphy B&W TV’s

Oil Filled Line Output Transformer

A well known problem with the Murphy Astra television range and pretty much the Achilles heal of this TV, is the failure of the oil filled line output transformer. However, there is solution and that is to perform a LOPT ( Line Output Transformer) substitution. Other engineers have transplanted in the Thorn “Jelly pot” LOPT, which I believe was the red one as used in the 950-series. However adding the Thorn LOPT requires circuit modifications, my solution of LOPT replacement does not require any modifications whatsoever, it’s a direct drop in.

Chassis below fitted with the original Oil filled LOPT

Close up of Oil Filled LOPT

The HR-Diemen LOPT for Substitution

You might be wondering what on earth you would use as a direct replacement, from my experimentation I have found the HR- Dieman Model HR-651-RSI, is a direct drop in. This LOPT is available at the time of writing this article from E-Bay in Germany. That is where you must search, and the following term will find you the source.

“HR Line Transformer HR-651-RSI for TELEFUNKEN”

As mentioned above, the beauty of this LOPT substitution is that no circuit modifications are required.

The HR-Dieman LOPT

How To Perform the Substitution

Below you will find photos showing exactly how to connect and where the colour coded chassis wires are to be connected to the replacement LOPT tags. When the LOPT arrives it will contain paperwork, but it is in Spanish and there are errors which if followed would result in the LOPT not working. Therefore to save you all the pain I have worked it all that out for you.

The LOPT also comes with a solid state EHT rectifier stick installed, it is entirely your choice if you wish to install the LOPT with this or revert back to original valve EHT rectification. In my experience I have used it with both configurations without any problems. As I say a personal preference, thosw who are keen on originality will likely opt for reverting to Valve.

Note:1 The LOPT also comes with the linearity coil (see last photo) this can be connected anywhere between the scan coils. For example between 6a and the scan coil.

Caveat: Please be aware this has only been tested on a non-flywheel sync TV. If you have plugin module for flywheel sync, you will have to obtain a direct sync module, good luck with that!