Thread: HP 54845 A with bad acqusition assembly.

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Permlink Replies: 5 - Pages: 1 - Last Post: Apr 30, 2012 5:12 PM Last Post By: nltech8
magoknes

Posts: 3
Registered: 10/01/09
HP 54845 A with bad acqusition assembly.
Posted: Jul 26, 2010 2:35 PM
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Hello.
My 54845 a fails time base and pattern trigger on self test. I`ve tried all over for a year to find a new or used acqusition board but without any luck. I have no schematics or layouts of components for the unit at all. So it makes it kind of impossible to troubleshoot to. Is there anybody out there who knows this unit well and will be kind enough to guide me in the right direction. Is there a download link for schematics for the 54845 A.
I`ll appriciate any help.
Thank you.
nltech8

Posts: 4
Registered: 08/13/10
Re: HP 54845 A with bad acqusition assembly.
Posted: Aug 13, 2010 12:38 PM   in response to: magoknes in response to: magoknes
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I wish I had schematics too. We've seen a fair number of trigger failures due to broken/loose solder connections on IC's on the bottom of the board. Try checking the pins on U166, U169, U170 and others in that area. The leads my look soldered, but will come loose when picked at with a probing tool. Good luck!
magoknes

Posts: 3
Registered: 10/01/09
Re: HP 54845 A with bad acqusition assembly.
Posted: Nov 19, 2011 11:03 AM   in response to: magoknes in response to: magoknes
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Hello.
Thak you for your ansver, but it did not help our problem.
Our HP 54845 A fails on self test.: Trigger Level, Pattern Trigger, and Time Base.
Acording to troubleshooting tree the acqusition board schould be replased.
Please advice.

Best regards
Pingvin Kuldeindustri Ltd

Magne Oknes
micahcruz

Posts: 6
Registered: 02/09/12
Re: HP 54845 A with bad acqusition assembly.
Posted: Feb 22, 2012 11:03 AM   in response to: magoknes in response to: magoknes
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I know it sounds crazy but just try to reload/reinstall the firmware for the scope. I have had many 548xx scopes with trigger failures during cal routines and reloading the firmware solved this problem
magoknes

Posts: 3
Registered: 10/01/09
Re: HP 54845 A with bad acqusition assembly.
Posted: Apr 7, 2012 11:37 AM   in response to: micahcruz in response to: micahcruz
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Hello.
Thank you for responding. The Agilent representative here in Norway suggested the same as you did but back in 2009 after i bought the unit on eBay and realised it was a lemon. They diden`t have 1.44 MB floppy disks to reinstall so they sendt the harddrive to Germany for reinstallation/update. But it diden`t help. The unit calls for self calibration but it hengs after a while and has to be reset. The same thing on auto-schale. It hengs and no tasce for any channel appares. It never did.
It fails on self test on the folloving:
FISO. Needs recalibrate to remove data bit error. No mux gain change measured. Test Gain Failed. Fails on Line Trigger. No trigger found in line trigger source mode. Test trigger level failed. Test Pattern Trigger Failed. Test Timebase Failed.
Out from that. Is it the acqusition bord that is at fault. If so. Can it be repaired? You seam to have very good knowledge to a veraity of HP testequipments and I`ll appriciate your help fyrther very mutch.
Happy Easter.
nltech8

Posts: 4
Registered: 08/13/10
Re: HP 54845 A with bad acqusition assembly.
Posted: Apr 30, 2012 5:12 PM   in response to: magoknes in response to: magoknes
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Line trigger errors/failures are usually due to the 2 wire cable that plugs into the side of your acquisition board between 2 of the large white power cables being damaged or unplugged. If someone has previousy removed the board, it is quite common for that cable to fall back through the hole in the chassis and then get over looked when re-assembling. I've forgotten to plug it back in a couple of times myself. The fiso re-calibration error should go away, once the unit passes the user calibration.
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