Scope, RTC

Guest
Got this HP 54501, raster based CRT scope Indications are that the NVRAM chip, which is more of an assembly because it has an internal battery has died. That is most likely due to the battery.

The battery has a connection to pins on it. ;the presumption at this time is the battery is in too poor state of charge to operate the chip. This has all the setup information in it so it is not likely to work with it in a dead state.

There has been some speculation about just taking the proper voltage to those IC pins. I think if we got access to that all it would take is a battery and two wires.

Here is a thread on it from Tekscope@groups.io;

https://groups.io/g/TekScopes/topic/2432a_ram_battery_module_or/7655544?p=Created,,,20,2,20,0::,,,0,0,0,7655544

They describe a similar situation with the Tek 2432 and 2440.

In this, the chip is described as;

Dallas
DS 1235YW-120

One guy mentions the exact number in the Tek, so obviously the data will not be right, plus the calibration information will be who knows.

I say keep the calibration. For example an old bigscreen, well not that old old. Had some bad things going on in the convergence, they said "Just change it, throw that one in and align it". Bullshit, I took the parts out of the boneyard replacement and fixed the original and when I put it in the convergence was perfect, as if it had never been touched.

So I think that would be best for this. Just give it the damn voltage it wants. It works, evleybody appy !

What are the odds ? I will do anything within reason, up to maybe a Joule thief with a warning beeper.
 
On 3/9/20 10:18 PM, jurb6006@gmail.com wrote:
Got this HP 54501, raster based CRT scope Indications are that the NVRAM chip, which is more of an assembly because it has an internal battery has died. That is most likely due to the battery.

The battery has a connection to pins on it. ;the presumption at this time is the battery is in too poor state of charge to operate the chip. This has all the setup information in it so it is not likely to work with it in a dead state.

There has been some speculation about just taking the proper voltage to those IC pins. I think if we got access to that all it would take is a battery and two wires.

Here is a thread on it from Tekscope@groups.io;

https://groups.io/g/TekScopes/topic/2432a_ram_battery_module_or/7655544?p=Created,,,20,2,20,0::,,,0,0,0,7655544

They describe a similar situation with the Tek 2432 and 2440.

In this, the chip is described as;

Dallas
DS 1235YW-120

One guy mentions the exact number in the Tek, so obviously the data will not be right, plus the calibration information will be who knows.

I say keep the calibration. For example an old bigscreen, well not that old old. Had some bad things going on in the convergence, they said "Just change it, throw that one in and align it". Bullshit, I took the parts out of the boneyard replacement and fixed the original and when I put it in the convergence was perfect, as if it had never been touched.

So I think that would be best for this. Just give it the damn voltage it wants. It works, evleybody appy !

What are the odds ? I will do anything within reason, up to maybe a Joule thief with a warning beeper.
Click to expand...

Is the "NVRAM chip" just SRAM with a backup battery in a unit package?

Is getting an appropriate-sized SRAM chip and external battery and
mounting to a bodge-board that slots into the original socket a
possibility? Sounds like an easier proposition of the original package
is say potted
 
On 3/9/20 10:18 PM, jurb6006@gmail.com wrote:
Got this HP 54501, raster based CRT scope Indications are that the NVRAM chip, which is more of an assembly because it has an internal battery has died. That is most likely due to the battery.

The battery has a connection to pins on it. ;the presumption at this time is the battery is in too poor state of charge to operate the chip. This has all the setup information in it so it is not likely to work with it in a dead state.

There has been some speculation about just taking the proper voltage to those IC pins. I think if we got access to that all it would take is a battery and two wires.

Here is a thread on it from Tekscope@groups.io;

https://groups.io/g/TekScopes/topic/2432a_ram_battery_module_or/7655544?p=Created,,,20,2,20,0::,,,0,0,0,7655544

They describe a similar situation with the Tek 2432 and 2440.

In this, the chip is described as;

Dallas
DS 1235YW-120

One guy mentions the exact number in the Tek, so obviously the data will not be right, plus the calibration information will be who knows.

I say keep the calibration. For example an old bigscreen, well not that old old. Had some bad things going on in the convergence, they said "Just change it, throw that one in and align it". Bullshit, I took the parts out of the boneyard replacement and fixed the original and when I put it in the convergence was perfect, as if it had never been touched.

So I think that would be best for this. Just give it the damn voltage it wants. It works, evleybody appy !

What are the odds ? I will do anything within reason, up to maybe a Joule thief with a warning beeper.
Click to expand...

I've worked on a some pieces of uP-controlled gear from the 80s that
store program work-data in battery-backed SRAM that's expected to still
be there from the last time when the kit powers up, even if the user
hasn't changed any settings from stock themselves.

So if the SRAM battery fails it's often borked on power-up; garbled
display, controls don't work right. Then a factory-reset procedure
refreshes the SRAM and all works fine until it shuts down, start up,
borked again.

Wash rinse repeat until the battery is replaced
 
On 10/3/20 1:18 pm, jurb6006@gmail.com wrote:
Got this HP 54501, raster based CRT scope Indications are that the NVRAM chip, which is more of an assembly because it has an internal battery has died. That is most likely due to the battery.

The battery has a connection to pins on it. ;the presumption at this time is the battery is in too poor state of charge to operate the chip. This has all the setup information in it so it is not likely to work with it in a dead state.

There has been some speculation about just taking the proper voltage to those IC pins. I think if we got access to that all it would take is a battery and two wires.

Here is a thread on it from Tekscope@groups.io;

https://groups.io/g/TekScopes/topic/2432a_ram_battery_module_or/7655544?p=Created,,,20,2,20,0::,,,0,0,0,7655544

They describe a similar situation with the Tek 2432 and 2440.

In this, the chip is described as;

Dallas
DS 1235YW-120

One guy mentions the exact number in the Tek, so obviously the data will not be right, plus the calibration information will be who knows.

I say keep the calibration. For example an old bigscreen, well not that old old. Had some bad things going on in the convergence, they said "Just change it, throw that one in and align it". Bullshit, I took the parts out of the boneyard replacement and fixed the original and when I put it in the convergence was perfect, as if it had never been touched.

So I think that would be best for this. Just give it the damn voltage it wants. It works, evleybody appy !

What are the odds ? I will do anything within reason, up to maybe a Joule thief with a warning beeper.
Click to expand...

Does this help at all:
<https://www.instructables.com/id/HP-54501A-NVRAM-Replacement/>

CH
 
On 2020/03/09 7:18 p.m., jurb6006@gmail.com wrote:
Got this HP 54501, raster based CRT scope Indications are that the NVRAM chip, which is more of an assembly because it has an internal battery has died. That is most likely due to the battery.

The battery has a connection to pins on it. ;the presumption at this time is the battery is in too poor state of charge to operate the chip. This has all the setup information in it so it is not likely to work with it in a dead state.

There has been some speculation about just taking the proper voltage to those IC pins. I think if we got access to that all it would take is a battery and two wires.

Here is a thread on it from Tekscope@groups.io;

https://groups.io/g/TekScopes/topic/2432a_ram_battery_module_or/7655544?p=Created,,,20,2,20,0::,,,0,0,0,7655544

They describe a similar situation with the Tek 2432 and 2440.

In this, the chip is described as;

Dallas
DS 1235YW-120

One guy mentions the exact number in the Tek, so obviously the data will not be right, plus the calibration information will be who knows.

I say keep the calibration. For example an old bigscreen, well not that old old. Had some bad things going on in the convergence, they said "Just change it, throw that one in and align it". Bullshit, I took the parts out of the boneyard replacement and fixed the original and when I put it in the convergence was perfect, as if it had never been touched.

So I think that would be best for this. Just give it the damn voltage it wants. It works, evleybody appy !

What are the odds ? I will do anything within reason, up to maybe a Joule thief with a warning beeper.
Click to expand...

You can always carefully cut the top off the Dallas RAM and access the
lithium button battery and replace it - we used to do that in video
games that used this brand of battery NVRAM, but why not simply grab a
62256 NVRAM such as used in pinball games and be done with the
batteries? Assuming speed isn't a major factor that is...

Caution - link to my sales shop for this Cypress based NVRAM:

https://www.flippers.com/catalog/product_info.php/62256-nvram-module-p-8729

/Caution

John :-#)#
 
On Mon, 09 Mar 2020 19:18:02 -0700, jurb6006 wrote:

Got this HP 54501, raster based CRT scope Indications are that the NVRAM
chip, which is more of an assembly because it has an internal battery
has died. That is most likely due to the battery.

The battery has a connection to pins on it. ;the presumption at this
time is the battery is in too poor state of charge to operate the chip.
This has all the setup information in it so it is not likely to work
with it in a dead state.

There has been some speculation about just taking the proper voltage to
those IC pins. I think if we got access to that all it would take is a
battery and two wires.
Click to expand...
If the battery still has some voltage on it, like above 1 - 1.5 V, the
RAM contents may still be maintained, but not readable by the CPU. So,
getting the required 3 V or so on it may bring back the system. If the
data is totally gone, then you will have to go through whatever
calibration procedures are required.

Jon
 
On Tuesday, March 10, 2020 at 3:07:02 PM UTC-4, Jon Elson wrote:
On Mon, 09 Mar 2020 19:18:02 -0700, jurb6006 wrote:

Got this HP 54501, raster based CRT scope Indications are that the NVRAM
chip, which is more of an assembly because it has an internal battery
has died. That is most likely due to the battery.

The battery has a connection to pins on it. ;the presumption at this
time is the battery is in too poor state of charge to operate the chip.
This has all the setup information in it so it is not likely to work
with it in a dead state.

There has been some speculation about just taking the proper voltage to
those IC pins. I think if we got access to that all it would take is a
battery and two wires.

If the battery still has some voltage on it, like above 1 - 1.5 V, the
RAM contents may still be maintained, but not readable by the CPU. So,
getting the required 3 V or so on it may bring back the system. If the
data is totally gone, then you will have to go through whatever
calibration procedures are required.

Jon
Click to expand...

My (increasingly volatile) memory says that this module is SRAM with a lithium cell to keep it alive. When the scope is powered, it would power the SRAM, bypassing the battery. So, if what you've got now is garbled, it's likely that the SRAM lost power completely and you are SOL as far as the data in there goes.

Of course, I could be wrong - it's been quite some time since I used one of those.
 
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