Pye 14 inch monitor type 842822

This is the only known surviving Pye monitor of the type that was originally installed in MCR21. This example was made in late 1963, so could have been in one of the MCRs, or installed elsewhere. There is no record of it’s use.  It is serial number 130.

Controls:- H. position, H. width, H. hold, AC on, Brightness, Focus, Contrast, I/P 1 or 2, Sync int/ext,  V. height, V. Centre

Rear of the monitor

The monitor rear with 2 inputs & Ext. Sync. Additionally there is a third auxiliary test video input which produces a negative image and is added to the other selected input.  If it was fed with “grille” it could be used for adjusting camera scan linearity.

The top left switch is B+ on/off and next to it, Hor. Osc trig/AFC

PSU side open

In many respects the monitor is nicely made with front and rear castings. Whilst it is the same size as it’s predecessor the build is quite different. It has excellent accessibility with fold down chassis that unplug for quick replacement. All pre-set controls are clearly marked and the individual components have their part number on them. 

Chassis Left to right: PSU regulator, Field scan, Video amplifier.

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EHT side open

This is other side with the sync separator  and EHT units. The monitor has and independent EHT section and  in this monitor it has given trouble and is in a poor state. The oscillator valve is a EL360 pentode, the transformer is arranged as a tripler with 3 QU37A rectifiers. The regulation is done by a shunt stabilizer valve type A2637. 

The line scan is by another EL360 valve. The monitor auto-senses the input line standard and switches automatically. 

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Pye 14 inch monitor type 8428243

This is next model that Pye made just 3 years later, apart from the two EHT rectifiers it is all solid state. It has the same screen size as the original monitors and is simliar in function. We do have the correct number of these and we plan to use them in place of the 842822 monitors. 

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Monitor rear

The rear of the monitor has very clean lines with only the mains transformer protruding.  The red “dot” is an overload trip, above it is the 405/525/625L standards change switch. Unlike the 842822 it is not auto sensing for line standard.

This monitor is serial number 72.

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Monitor side open

The inside is nicely laid out with a large PCB on either side. Line and PSU on the near PCB and the video amplifier and frame scan on the far one.  In the centre section there is a diecast aluminium box with the free running regulated EHT generator. It has a voltage doubler with two EY87 valves.

The accessibility to the two main PCBs for maintenance is good and the EHT unit can be accessed from below by removing just eight screws. 

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Monitor Working

This monitor is in working order and and ready for installation.

It was last serviced in 2014. For monitors that are now over half a century old!! the reliability is good, once a modicum of work is done on known problem areas.
It is hoped that we will be able to keep these monitors working well into the future provided spare CRTs type M36-12W & M43-12W can be found.  

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8.5 inch Peto Scot Monitor type TB1204A

This monitor is to be installed in Zone 1 the front engineering area, up above the maintenance bench.  It is connected to the engineering output of the preview matrix via the Tek 515 oscilloscope which was used as the waveform monitor.

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8.5 inch Peto Scot Monitor

The rear view with just a single loop trough input for picture. The Ext sync input was not used. 

This monitor has yet to be restored and the XLR LNE connector will be replaced with the original EP4 connector.  

The EP5 connector is for remote control.

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Peto Scot Monitor inside view

The monitor has been unused for a long time and is awaiting restoration but it appears to be in quite good and complete condition. 

It is serial number 388.