Hugo Holden
Veteran Member
I have written up an article about early PET VDU's.
One aspect of it is the general restoration of the VDU.
Another aspect is about modifications to the VDU. These are not absolutely necessary, but they can improve the performance and help protect the VDU from damage in the event it is fed with abnormal signals from the computer board.
The article essentially has 13 sections and as usual got bigger than I thought it would when I started it.
One aspect is about the analysis of the LOPT (Line output transformer, aka Horizontal output transformer). There is not a lot of good specific detail on this in the literature, so I have tried to put it all in one place, how to test these with the generator & scope.
Also how one might adapt in LOPT's from other VDU's. The LOPT's on these early VDU's are not available as replacement parts.
One interesting result, is that it is dead easy to check the LOPT in circuit, without even having to remove it from the pcb, with a dual resonance test as explained in the article.
Anyway, here is the article first draft.
Aspects of it might help those planning to restore one and re-cap the pcb:
One aspect of it is the general restoration of the VDU.
Another aspect is about modifications to the VDU. These are not absolutely necessary, but they can improve the performance and help protect the VDU from damage in the event it is fed with abnormal signals from the computer board.
The article essentially has 13 sections and as usual got bigger than I thought it would when I started it.
One aspect is about the analysis of the LOPT (Line output transformer, aka Horizontal output transformer). There is not a lot of good specific detail on this in the literature, so I have tried to put it all in one place, how to test these with the generator & scope.
Also how one might adapt in LOPT's from other VDU's. The LOPT's on these early VDU's are not available as replacement parts.
One interesting result, is that it is dead easy to check the LOPT in circuit, without even having to remove it from the pcb, with a dual resonance test as explained in the article.
Anyway, here is the article first draft.
Aspects of it might help those planning to restore one and re-cap the pcb: