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2465B CTT options board faults
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Jean-Paul
Bonjour a tous:
Working on SN B062 2465B, GPIB and CTT/WR options. Faults in CTT option. Affects triggering. All cables are correctly attached to options board, A5 board is not at fault, SMD leaks and damages repaired, swapping other good A5 does not remove fault and removing options board clears the fault. Turn on test Test 05, Fail 42 LINE TRIG signal to the Trigger hybrid. Line sig is OK and trig hybrid U500 can be replaced with no changes. CTT test errors: 81 fail 03 82 fail 3F 83 fail 30 84 fail 40 85 fail 03 86 fail 02 87 fail 58 The 5 pages flow charts of option serv man do not point to a good procedure. I suspect that the EEPROM on options board U5930 27515 may have bad data. Note: NO TV or HDTV options, no REF FREQ ext in, only CTT/WR. GPIB on separate board seems OK and no effect to insert or remove GPIB. Any experience or assistance on CTT board faults greatly appreciated. Mille mercis! Jon
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Chuck Harris <cfharris@...>
There are two cases where the 2465B needs a perfect
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trigger hybrid that works in all of its functions: 1) the automatic measurements for frequency. 2) anything using a CTT board. I have found trigger hybrids that are perfect in all respects for normal operation, that fail in those two functions. Beware of replacement trigger hybrids. There is quite a trade in hybrids that have failed on ebay. The same guy that sells 2445B's rebadged as 2465B's has sold bad hybrids, as being tested good, to my customers. -Chuck Harris Jean-Paul wrote:
Bonjour a tous:
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Jean-Paul
Dear Chuck: Many thanks
I had tested the U500 trigger hybrid by exchanging for another from ebay (got two for $30) not from our friend Alex. Neither of the exchanges made any difference. Instead I should use a known good scope with working CTT . I can also swap out the option board of a know good CTT. All the Best, Jon
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Chuck Harris <cfharris@...>
I just finished remotely helping a friend with his scope,
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and was getting my confidence pretty well shaken when two trigger hybrids both failed. It took a third, this time from our friend in Greece, to fix the problem. As I said earlier, there is a booming business in selling almost good trigger hybrids on ebay. The CTT and the automatic frequency measurement both use a function in the trigger hybrid that isn't used by any other scope function. A perfectly performing scope can have a trigger hybrid that won't measure frequency, or work with the CTT. I wish I could say that just replace this part or tweak that pot, and your hybrid will come back to life, but I haven't figured out what that part is, or where that pot resides... -Chuck Harris Jean-Paul wrote:
Dear Chuck: Many thanks
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Jean-Paul
Dear Chuck many thanks again, especially the warnings re crippled hybrides on epay.
As I have four others open at the moment that work I have fourth chances to find a working trigger hybrid. I shall check for 100% CTT operation and all tests on two other CTT working units, then try swapping out, for a known good one. What fun! Enjoy Jon
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