05-01-2019, 03:39 PM
The very first set I had was a Pye VT4, given to me when I started work. It had an excellent picture, as one might expect from the extras that Pye added but one night, while were watching it, the line frequency changed abruptly and shot off heaven knows where. It was quite late at night, so that was the end of play for the day.
The following night I started to look into it. First, I got the line speed correct but whether I had to adjust the trimmer, I can't remember - well, it was 58 years ago!
No line sync, not the slightest trace. Ah, diodes I thought! No change! Feed from sync separator? Nope! Feedback pulse from the LOPT? Nope! Of course, no scope in those days - we didn't even have one at work! I was rapidly running out of ideas, resorting to changing components at random, even though I could see no logical reason for them being responsible.
Eventually, I had to admit defeat.
One day my colleague Ray, 2 years my senior, asked "How are you getting on with you VT4?" "Given up". I said. So, he suggested we get it in and he'd take a look at it for me.
Of course, everything he thought of, I'd been there before him! Very soon too, he came up against a brick wall but he persevered. Fortunately, it was a slow day with nothing pressing that I couldn't handle.
Time passed and suddenly there was a cry: "Found it!"
I walked along the line of benches and there was the VT4, with a perfectly locked picture. *What was it?" Ray motioned toward an electrolytic lying on the bench with two wires connected to the chassis. "Main smoothing" he said.
A hard earned lesson but one I'll never forget!
The following night I started to look into it. First, I got the line speed correct but whether I had to adjust the trimmer, I can't remember - well, it was 58 years ago!
No line sync, not the slightest trace. Ah, diodes I thought! No change! Feed from sync separator? Nope! Feedback pulse from the LOPT? Nope! Of course, no scope in those days - we didn't even have one at work! I was rapidly running out of ideas, resorting to changing components at random, even though I could see no logical reason for them being responsible.
Eventually, I had to admit defeat.
One day my colleague Ray, 2 years my senior, asked "How are you getting on with you VT4?" "Given up". I said. So, he suggested we get it in and he'd take a look at it for me.
Of course, everything he thought of, I'd been there before him! Very soon too, he came up against a brick wall but he persevered. Fortunately, it was a slow day with nothing pressing that I couldn't handle.
Time passed and suddenly there was a cry: "Found it!"
I walked along the line of benches and there was the VT4, with a perfectly locked picture. *What was it?" Ray motioned toward an electrolytic lying on the bench with two wires connected to the chassis. "Main smoothing" he said.
A hard earned lesson but one I'll never forget!
