54615B repair - no boot

[Iridium]

Hello,

My oscilloscope HP54615B recently freeze during boot. Service manual : https://engineering.case.edu/lab/circuitslab/sites/engineering.case.edu.lab.circuitslab/files/docs/Agilent_54615B_54616B_54616C_Oscilloscopes_User_Service_Guide_.pdf
The supply seems to be ok (with or without load...), and the service manual just said me to buy another motherboard.... Not really usefull.
In the 54615B, i found a NVRAM M48Z18 https://eu.mouser.com/ProductDetail/STMicroelectronics/M48Z18-100PC1?qs=eb%2FRSZx1fMtLBqwnBmHVJw%3D%3D, with a retention time of 10 years.
Can this component be the problem?

Thank you a lot for your help, and sorry for my bad english.

Iridium

[m k]

Is "No module installed" a normal text?

Is there any moment you can read the top line, is it steady?

Manual page 4-34 step 5 has
"logo and copyright text, followed by a graticule with text at top of the display"

Your boot is clearly stopped very early.
Maybe something is disconnected.

[factory]

The module is an optional extra that fits on the back, there are several types for RS232 or GPIB connections and/or & measurement storage.

David

[Iridium]

Hello,

Is "No module installed" a normal text?

Yes, it's a normal text, already displayed.

Manual page 4-34 step 5 has
"logo and copyright text, followed by a graticule with text at top of the display"

Yes, the manual ask to check the low voltage, but all voltages are ok, and the fan is running.

Your boot is clearly stopped very early.
Maybe something is disconnected.

Nothing disconnected  (verified with my multimeter)

Thank you for your time !

Iridium

[m k]

Disconnected can mean anything, like chips and cables but also stuff like bad solder joints.

Are topmost dots random?
Power on the machine few times and take pictures.
Wait a moment before powering it up again.

You should also find a way to figure out what is the true situation of the scope, it can stil be operational but with wrong picture.
For that a 2nd scope is an obvious solution but any indication is enough.

If topmost dots are not random then software failure is more probable.

You're looking a CRT monitor and it has a picture so it's fine.
Next in line is a display controller and it is outputting that picture just fine but it can also be totally independent so its input side is unknown.
Rest are also unknown until you can prove otherwise.

If probe calibrator is coming alive only some time after picture hangs it may be an indicator.

[Iridium]

Hello,

"Are topmost dots random?"

Yes !

If probe calibrator is coming alive only some time after picture hangs it may be an indicator.

The calibrator output is set 5V. I can't use the frequency mode (2.49kHz output) because I have to select this mode with software keys; impossible without display

Some news : if I connect the module, the oscilloscope take more time before freeze, and the grid have enough time to be displayed (see attachement).

Thank you !

[m k]

Very good.

You can do device inquiries through HP-IB.
If they are answered you know the device is still operational, sort of.

Is it normal that HP logo and grid are present simultaneously?

Top line has one extra dot.
Dotted line can also be a normal uninitialized situation you can't normally see.

If your inquiries are answered try some measurements through HP-IB.
Accuracy is not needed, you're just trying to find out how sane the scope section is.

[Iridium]

Hello,
I'm searching how to use the module (I never use this interface).

Is it normal that HP logo and grid are present simultaneously?

Yes, for a short time.

[free_electron]

DEFAULTS LOADED your nvram is corrupted. empty battery

[bostonman]

DEFAULTS LOADED your nvram is corrupted. empty battery

I'm curious, can replacing the NVRAM (or battery as I've seen some of these with battery access) reload all the information or does something need to be reprogrammed?

[m k]

Hello,
I'm searching how to use the module (I never use this interface).

Is it normal that HP logo and grid are present simultaneously?

Yes, for a short time.

If you have other modules available you can test them also.
After first boot you get that defaults loaded or similar text but if setup memory is ok the text should stay away during next boot.

Is there a real time clock, was it keeping up?

Setup memory has obviously different sections for different settings, it's also possible that one part is ok and other part is not.
Real time clock and setup memory are not necessary in the same chip but many times they are.

If you have a serial port interface you can communicate with the scope using a simple terminal or emulator.

[Iridium]

hello,
sorry for the delay.

Is there a real time clock, was it keeping up?

No RTC found

If you have a serial port interface you can communicate with the scope using a simple terminal or emulator.

I search for this.

[Iridium]

Hello,

After test, I can't access to the oscilloscope throught the external module.

My problem seems to be the same as this video :
So, I will try with another NRAM module...

[merox]

if I connect the module, the oscilloscope take more time before freeze, and the grid have enough time to be displayed (see attachement).

My 54200A behaved more or less the same than your 54615B, the culprit in my scope were corrupted/dying EPROMs.

Had some new EPROMs burned, inserted them an the scope and it started working like nothing had ever happened.

[bostonman]

Had some new EPROMs burned, inserted them an the scope and it started working like nothing had ever happened.

Did you burn them prior with anticipation of them getting damaged or you found the firmware somewhere?

If the issue with the 54615B is the same, I'm sure he'll be looking for the firmware.

[merox]

Did you burn them prior with anticipation of them getting damaged or you found the firmware somewhere?

I got my 54200A in non-working condition and searched for quite some time till I finally found the firmware online. The original source is long gone but I reuploaded them to KO4BB.

But that won't help in this situation. I've searched for the Firmware of the 54600B series myself and couldn't find it anywhere. But I might have a similar looking scope at work, I'll have a look if it's the same - maybe I can dump the firmware of that one. I'll let you know in that case.

[Runco990]

Replace the NVRAM or do the battery mod to it.  Then run the built in calibration and the scope will be fine.  I have done LOADS of these.  The NVRAM battery is dead.  Don't overthink it.  Typical failure.

The later series has the same problem now, but the battery is a button cell soldered to the main board, much easier to change.

[bostonman]

I have one of these and just curious how many NVRAM chips are on the board.

I may buy some blank ones before they go obsolete so I have them for future needs (although the battery may die before I use them).

[Fixed_Until_Broken]

But that won't help in this situation. I've searched for the Firmware of the 54600B series myself and couldn't find it anywhere. But I might have a similar looking scope at work, I'll have a look if it's the same - maybe I can dump the firmware of that one. I'll let you know in that case.

I have a 54600B Do you need a dump of the ROM? I have a mini pro not sure if it can read the ROM IC that's in these. if it can I am happy to read it.