2465B CTT options board faults


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


Chuck Harris <cfharris@...>
 

I just finished remotely helping a friend with his scope,
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

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









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


Chuck Harris <cfharris@...>
 

There are two cases where the 2465B needs a perfect
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:
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














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