PYE Monitor Mayhem Part 1 - Paul makes a start on bringing a number of Pye monitors back to life.
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- Опубліковано 13 бер 2024
- In preparation for a complete overhaul Paul carries out a careful appraisal of the condition of a pair of PYE TV monitors - the same models used on MCR21.
Long-time storage in damp conditions makes the task difficult however a basic surface clean is enough to enhance the looks of the cabinet. As you might expect a preliminary look at the electronics points to much work being required - more to be seen in later videos. Stay tuned! - Наука та технологія
A labour of love, sweat and tears.....
Bad news on the CRT. Probably an "air-tube" (down to atmosphere)
The centre burned phosphor dot is from an undeflected beam during switch off. Usually the driving electronics would hold the CRT in grid cut-off long enough for the EHT to decay. The capacitor in that circuit probably failed first. The CRT can only be saved by cutting and rebuilding.
The centre "halo" is possibly damaged phosphor from ion bombardment. For this vintage CRT there is/was an ion-trap permanent magnet on the CRT neck (which may have fallen off?)
CRT design progressed to "aluminized screens", a thin layer of metal deposited behind the phosphor, that blocks ion bombardment and also increases light output (acting as a mirror) Not sure if this tube has that feature?
These phosphor faults are not related to loss of vacuum.
The CRTs in these monitors are of the aluminised types so they don't have the ion trap magnet. It has been suggested that the phosphors can show this pattern from the disruption caused by sudden loss of vacuum. Luckily we were able to swap in a good CRT from the worst of the other examples to make one good one from the two.
Aquadag, my friend, don't you peel away so easy?
That second monitor CRT looks like it may have gone to air. The dark circle and the missing phosphor in the center is indicative of vacuum loss.
You may be correct - it will be covered in a future video.
Video on PL259s not BNCs that's pretty heavy duty British eng.
Same thing in the USA. We didn't see BNC connectors on broadcast gear until the early 1970s.
Some British broadcast kit used a coaxial connector called MUSA (Multiple Unit Steered Array) developed for quick changing of Aerial taps, probably for WW-II era radar. Was more compact than PL259/SO259 hardware, and didn’t have the fiddly threaded part.
@@pstonardThanks - yes I remember MUSA connectors - they were very exotic and normally only obtainable from Canford or FFD ?