EVVIVA! (typycal Italian expression of great joy)
I was closing the email below, when I remembered something I read in the 11302 Firmware Replacement Technical Bulletin that very kindly Hakan Hintze sent to me with the 3.1 upgrade eproms. That sounded like "If the instrument fails to do a successful EA, run the GRAT-PREP procedure, Test List No. 24 in the CATS disk¡±.
This procedure allows to tune the screen alignment procedure and is really well done; it as formerly named in the manuals as ¡°19 .BEAM_REGISTRATION¡±. It allows to set the scanning marks position and intensity and allows to see what the photodiodes ¡°see¡±. I carefully performed it and ¡it works!
Thanks to everybody, without your help I could not succeed!
Gianni
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This oscilloscope is very complex and the first approach is disorienting. After several days with my brain inside it and in the manuals, perhaps I begin to understand something. The baby has at least three different problems, and I could fully understand just one, very simple:
1) the ¡°stupid" problem: the dip switches are faulty and betray you blatantly - a stupid fault which creates great confusion. I temporary fixed them but I will replace them;
2) the ¡°main¡± problem: the Enhanced Accuracy most of the times fails.
The failure: The Enhanced Accuracy fails with the message ¡°Mainframe amplifier calibration failed¡±.
Early fail - When it fails, it fails always in the first stages. When it arrived to phase of ¡°E¡± symbol in the attached diagram, it always complete the EA;.
When it works? But when does it succeed? In a world: at cold.
Success: When I do the EA immediately after power on, subsequent to a period off (20 minutes off or more). In these conditions the markers on the CRT the calibration shows are much brighter, with a halo (and EA works). In this way, I could even do positively two consecutive EA. But fe minutes later the EA fails.
3) enlarged screen - from time to time the screen get badly shifted to the right and / enlarged vertically. Perhaps it is in consequence of a failed EA, but not always.
4) all the extended tests pass, even looping.
5) optical issues - I dismounted the front panel and checked everything. I cleaned the four photodiodes with isopropyl (but tey were clean). On the colored optical filter, I found a small abrasion just in the area interested by the beam scanning photodiodes. I tried to remove it with toothpaste but I could only worsen the situation. So I remounted it facing outside. But @Clark, I believe that you had a good intuition, as I explain below.
6) documentation mismatched - this is one of my biggest problem, because the TekCATS is much newer than the manuals I could find and the tests are very different, so I don¡¯t have a description for the various tests.
7) standardizers - I have no standardizers, so I try to do what I can. But there are tests, like vertical gain, where I could not find a workaoround.
BUT SOMETIMES IT WORKS! If I a) I keep it off for several minutes; b) switch it on and try the EA, in most of the times it works and the EA is correctly performed. And what I observe enforces the Clark¡¯s optical theory.
I noted that I can predict the result:
when the EA will succeed, the calibration marks are very bright, with a marked halo;
when the EA will fail, the calibration marks are not very bright.
The brightness of the calibration marks does not dependent from the front panel settings, but is preset by the system. I think that it is an analog problem from the CRT circuit.
