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HP 54600A trigger fail

Question asked by Fabien F4CTZ on Jun 26, 2008
Latest reply on Jun 25, 2009 by DL1ZP

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Hello,

My old 54600A has its trigger failed. I try to fix it and it seems that there is a level problem on the input of the operational amplifier AD96687 that creates the trigger signal : in normal trigger mode, when I change the trig level, I see the comparison level changing but it is always over the signal input of the AD96687.

Could someone help me ?

I'm looking for the schematic of the main board if nobody can help me. Where can I get it ?

Thanks very much.

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15 Replies

dnt Jun 26, 2008 9:31 AM
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It may take a while to answer this. Our resident expert on these scopes
is on vacation.
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ko2054 Jul 7, 2008 9:14 AM
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Hello F4CTZ (I hope I got your name right)

Anyway, please send me an email, ken_olson@agilent.com. I do have one set of schematics. I can loan them to you and you can make copies. However, I must have them back so that I can help the next customer out. I used to have three sets, but two were never returned by other customers so I am down to my last set. About 90% of customers do return items I loan them. Why the last 10% do not I will never understand.

In your email to me, please indicate your fedex shipping address with contact phone number and I can loan you the schematics for two weeks. The schematics are for the 54600A and 54601A scopes. They include schematics, parts list, and component locator. Part access might be an issue because that product is out of support life. Agilent does not stock parts forever. Sorry.
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DL1ZP Oct 4, 2008 2:35 AM
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Hello,

i was searching the internet for a solution to my recurring trigger problems and have stumbled over this thread. The situation described by the thread starter is very similar to mine. In addition to that i found that my 54601A is working ok at times (increasingly seldom) but then the trigger level has to be adjusted well out of the signal boundaries and seems to be floating away. You have to readjust repeatedly until it wonÂ´t trigger at all. If i leave the scope untouched for some time the trigger does come back.

What i was hoping now is that maybe F4CTZ has resolved the issue and can give me a hint as to what he has done. Maybe there is a set of schematics around that i can borrow. Any other means of help would also be higly appreciated.

Thank You!
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ko2054 Oct 7, 2008 1:27 PM
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Hello DL1ZP, I scanned the 54600A 54601A schematics into PDF files. There were large sheets so I had to break them up. You will have to put them back together after you print them out. But they are well labeled. At least it made sense to me. Because we frequently get this request, we placed a zip flie at the below web address for any customer to access. However, I cannot promise if any parts are still available. Those products are very old and were discontinued some years ago. The file is about 75MB.

http://www.home.agilent.com/agilent/edi ... id=1517718
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DL1ZP Oct 10, 2008 9:27 AM
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Hello again,
first of all THANK YOU very much for providing the schematics, it helped a lot. I think I found the mistake. The 4-channel multiplexer in the trigger unit (U9) which selects the trigger source adds a dc-offset to the trigger signal thus shifting the trigger level. The input of the mux is at the same level the DAC is providing at the other branch of the comparator but the output is about 0.3 volts off. The part is an Analog Devices AD9300 which i am on the hunt for now. Funny thing is that Analog Devices seem to know the part but do not give any information about it. Datasheets can be obtained through the usual internet sources though.

Regards, DL1ZP
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ko2054 Oct 10, 2008 9:49 AM
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Hello DL1ZP, The 546XXA model scopes are very old and it is possible the vendor may not have that part any longer. I do not know if they have a compatible replacement. Agilent does not stock those parts any longer so I cannot offer you anything. Let me know if I can be of other help.
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DL1ZP Oct 10, 2008 10:16 AM
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Hello ko2054,

Analog Devices just mailed me that they are having a problem with their search engine which will hopefully be fixed later today. They seem to still have the part in production so i might be in luck there. Secondly i found an ebay seller who has them in stock. I did business with him before in another issue and everything went well then. So in the end things could come out positive.
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DL1ZP Oct 23, 2008 3:37 PM
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Short update, after changing the suspicious part the scope is working again nicely.
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tonykara001 Dec 16, 2008 9:39 PM
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What a pleasant surprise to hear a user was actually able to fix their own scope!! And kudos to Ken Olson for supplying those schematics to all of us.

Now I'd like to see a set for the 54831M
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tonykara001 Dec 17, 2008 11:41 PM
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AD9300KP doesn't come up at Analog's site.

Who did you buy it from on ebay? It would be good to know because there are a lot of fake parts on ebay and a reliable source would be good to have.
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ko2054 Dec 19, 2008 10:05 AM
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Hello Tonykara,
Sorry for the delay in answering. I have been looking for schematics for the 54831M and so far I have struck out. I thought I had a set, but I was unable to find them. We keep such items in a common storage area and someone else may have taken them. Anyway, today I do not have any schematics for the 54831M. Sorry.
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tonykara001 Dec 19, 2008 8:01 PM
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Hi Ken,

Thank you for checking. I'll keep plugging away at this issue as time permits. Maybe in a month or so I'll ping you to see if those schematics have returned.

Have a good Xmas
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tonykara001 Mar 14, 2009 11:52 AM
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FYI, I purchased a couple AD9300KP from a guy on ebay named criticalparts, and it worked great!!!
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tonykara001 Mar 14, 2009 11:53 AM
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"
Hello Tonykara,
Sorry for the delay in answering. I have been looking for schematics for the 54831M and so far I have struck out. I thought I had a set, but I was unable to find them. We keep such items in a common storage area and someone else may have taken them. Anyway, today I do not have any schematics for the 54831M. Sorry.
"

Just pinging to see if those 54831M schematics have appeared?? If you can only find a paper copy, I would gladly scan them and create a big PDF file for you (us)
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DL1ZP Jun 25, 2009 3:17 AM
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Hi again,
i sort of lost track of this thread, so please excuse my later answer. The ebay seller who still has the AD9300KP in stock was "littlediode_usa"

Regards,
DL1ZP
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HP 54600A trigger fail

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