Author Topic: HP 54501A troubleshooting - repair  (Read 21533 times)

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Offline chihaxinh

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Re: HP 54501A troubleshooting - repair
« Reply #25 on: March 14, 2016, 02:06:12 am »
Hi rf-loop

How to use SRAM to replace NVRAM Dallas , can you guide me , i have another osc using NVRAM Dallas !

Many thank !
 

Offline Greg981

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Re: HP 54501A troubleshooting - repair
« Reply #26 on: March 21, 2016, 08:19:24 pm »
One more update (for posterity).  I have now determined the checksums of the four original EPROMS, and compared with the replacements that I got.  One very small difference found indicates that one EPROM had indeed started to lose its contents.  Original c/sums: 80005: ED60, 80006: 48E4, 80007: CB62, 80008: 220E.  Replacement (working) set: 80005: ED60, 80006: 48E3, 80007: CB62, 80008: 220E.  Sadly I can't get my programmer to talk to my PC (perhaps something to do with using a USB/RS232 converter) so I can't view the .HEX files to compare them.
 

Offline xrunner

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Re: HP 54501A troubleshooting - repair
« Reply #27 on: May 04, 2016, 10:35:13 pm »
I have a HP 54501A coming from Ebay. I was wondering about doing the full cal setup procedure. The service manual states you need to remove the PSU and reconnect it via an extender cable assembly, because some of the adjustments are under the PSU. Can this be done at all without the extender cable assembly?
« Last Edit: May 05, 2016, 07:50:53 pm by xrunner »
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Offline Smith

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Re: HP 54501A troubleshooting - repair
« Reply #28 on: May 05, 2016, 06:44:21 pm »
I don't think so, the cable between the PSU and the mainboard is quite short. As I remember correctly you can adjust the PSU itself without an extension.
Trying is the first step towards failure
 
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Offline xrunner

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Re: HP 54501A troubleshooting - repair
« Reply #29 on: May 05, 2016, 10:02:51 pm »
I don't think so, the cable between the PSU and the mainboard is quite short. As I remember correctly you can adjust the PSU itself without an extension.

Yea I saw how you can adjust the PSU OK. I've read quite a few threads on repairing and calibrating this unit, and not one ever mentioned the extender cable. I'm not sure if everyone out there has one of those cables in their junk box (LOL), or if they are somehow doing it by manipulating the PSU. I can almost see how it could be turned 90 deg. in-place and supporting it using some cardboard or other insulating stuff.

I guess I'll find out in a week or so.  :popcorn:
I am a Test Equipment Addict (TEA) - by virtue of this forum signature, I have now faced my addiction
 

Offline Smith

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Re: HP 54501A troubleshooting - repair
« Reply #30 on: May 06, 2016, 07:00:00 am »
I just used the automatic calibration on my 54502A, and everything works fine. Yes I double checked with external gear. There was no need to make adjustments on the main board. As I remember I never heared of anyone needed to make adjustments there.

An extender should be quite easy to make with some single male and female connectors and some not to thin wire. You don't really need the multipole male and female connector, unless you are planning to calibrate it verry often.
Trying is the first step towards failure
 

Offline bsalai

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Re: HP 54501A troubleshooting - repair
« Reply #31 on: July 31, 2016, 01:19:38 am »
Hi all,
I just got a 54502a. It was working fine when I picked it up, but as soon as I got it home, it developed a strange problem. As soon as I turn it in, something clicks (sounds like a small relay) and it shuts down just momentarily. Then it cycles again, sometimes rapidly, sometimes slowly. Occasionally I see a trace just for a second, but usually nothing.
I opened up the power supply, and it is very clean, no sign of trouble. I tried disconnecting the CRT board, but the trouble persists. It is difficult to pinpoint where the sound is coming from. My best guess is the front left corner of the main board, looking at the scope from the front. I haven't pulled the main board yet, but that's next.
Any thoughts??
Brad
Brad, W2EK
 

Offline dpm46

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Re: HP 54501A troubleshooting - repair
« Reply #32 on: August 17, 2016, 09:38:13 am »
Hi to all,
      I got a hp 54522a scope. Before I got problem with power supply and already repair it.  After the scope not being used for several months a new problem now develops.  Now have d/a, a/d and much more problem.  I turn the scope overnight hoping that the problem will go away. But when i go back in the morning I heard clicking on the scope and the display is on and off. I turned it off then turned on then there is a message like this: "SOFTWARE ERROR - Please record these numbers 0034 00003588 2000"  I open the scope and found out that the capacitor that I replaced before, failed again. I replaced again but same message.. Hope you can help me...

Regards,
Dave
 

Offline tinkertokyo

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Re: HP 54501A troubleshooting - repair
« Reply #33 on: February 22, 2018, 04:38:05 am »
Just in case it's of any interest to someone, I posted a video of me replacing the NVRAM on my 54501A.

 


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