Products > Test Equipment
Agilent 54835A scope (4 channel 1GHz / 4Gs/s) repair & uphack
alpher:
OK. So I sort of resurrected my 54845A project, managed to install new motherboard and bring the system back from the dead. Unfortunately wasn't able to install the 4.5B version of software :-//.
Anyway back to the 4.3A we go, up and running (was running uppgraded to 4.5 to).
There is a problem though, while before the scope passed all the self tests without any issues, also the calibration went through multiple times succefully, now it somehow developed "logic trigger" faults in all 4 channels during the cal process.
Self test fails on "logic trigger" and "pattern trigger".
So began to readup on the contents of HPX4S help file that someone suggested as good source to start board level troubleshooting.
Attached are pdf versions of the relevant sections from that help file, attached here because somehow microsoft made them really difficult to open in windows 10 :(.
The only immediately usefull info I foun there is as follws:
"
Error Symptom Diagnosis
The logic trigger test is somewhat self contained but does depend upon the serial input port and the 100 Mhz startable oscillator. The startable oscillator is used for pattern duration and range. To check the 100 Mhz startable oscillator:
1. Check the enable line toggles during the test. U84 pin 15
2. Varify that the oscillator is running during the test. U84 pins 18,19
The logic trigger also provides holdoff for the trigger system. A 50 Mhz free running oscillator is used as the holdoff clock.
1. Verify that the 50 Mhz osc. is running. U81B pin19
"
Has anyone been there before?
I've tried to scope signals at these pins but those MECL chips are pesky (negative supply) hard to trigger on the signal properly.
Moreover the signals are on only during 'logic trigger" test which last all but few seconds, is there a way to loop the test so it runs continuously ?
Really appreciate any poiners here.
I've attached pinouts for both chips U81 and U84 , 10H117, 10H105 as they are hard to come by for PLLC20 package.
alpher:
Decided to start from scratch, used 3.5 rec.iso and ghosted the image on another CF card, everything goes peachy till I reboot the scope.
It starts to load win98 then right away flashes DOS error message to the tune "error writing device PRN, abort , retry, fail" ?
:-//
At this moment I cannot even type, keyboard seems to locked up.
Has anybody encounter such a thing?
Could be that the 3.5rec.iso from Tony's archive is corrupted somehow?
I'm honestly stumped. :-//
alpher:
Short update, the "cannot write to PRN" error occurred for me on 2 motherboards, an Intel ZX chipset and Via VP3 . Somehow managed to install 3.5 recovery on Intel i810 mobo without hiccup. Unfortunately my conclusion is that something must be borked on my acqusition board. Managed to probe the signals on both the ECL chips (U81, U84) and they're there during the test.
Still all 4 channels fail on logic and pattern trigger, doesn't matter the mobo, be it i810 and software ver. 3,5 or ZX chipset and soft. 4.3 or 4.5, the result is the same.
So if someone has an extra A13 acqusition board, preferably cheap one, without FISO's or attenuators , as mine are working fine, I'' be willing to buy or trade for something else ( have a couple of sets of A5, A6 boards, maybe other stuff).
Thanks again.
nctnico:
Did you take the acquisition board out and inspect it? On mine one of the chips came loose. Be sure to work in an ESD safe environment otherwise you might do more damage than good.
alpher:
I did take it out a couple of times, didn't see anything obvious even under a magnifying glass. Without any more board level info I don't think that there is a chance of repair.
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