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Ramtron chip in place of Dallas

[email protected]
 

I haven't seem many Tek Video Scope posts here, but from info I read here about Issues with a TEK 2465, I can tell you that I've successfully replaced a Dallas 1225 chip with Ramtron16W08 with Dip Header on a TEK 1760 Scope, and it works fine after the change out.
With the help of a Programmer that supported the 1225 chip, I saved stock Ram Contents to disk, then I also changed one location of the contents of the memory from 0 to F and with that changed re-programmed into the 1225 or 16W08, that allowed me to use a 1750 SCH Option Board in the 1760.?
That location was 0F in the Ram contents... Changed 00 to 0F.
That, and some scope gain and config tweaks? allowed me to Take a 1760 Scope, and add a SCH Option Removed from a 1750 Scope (with bad CRT).? Prior to this memory 'poke' the SCH Option would not be activated when the SCH button was pressed......??
 

The Ramtron 16W08 family works very well in the 2465A and B
as both a replacement for the Dallas 1225, and as a replacement
for the battery and CMOS RAM in the "A" and early "B" scopes.

However...

Be warned that some EPROM programmers don't prime the pump
correctly with the FRAM chips. The CS is an address latch signal,
not a simple bus enable as it is with most RAM chips. This can mean
that your first, and last address will be in error, even though each
additional address will be fine.

In the 2465A or B scopes, the NVRAM is used as both an area to store
constants, and as system RAM. The system RAM controls the first
addresses as part of the interrupt vector array, and as such it is
restored every time the scope is powered up. Other instruments may
not do this.

To make the FRAM chips work happily in a scope with a separate battery
and CMOS RAM, you have to modify the battery test circuitry to fool
it into thinking the battery is always good.

( Short CR2371 and CR2370, replace CR2770 with 3.9K resistor, remove
battery, jumper + pad to - pad, install label over battery footprint
disclosing modification.)

-Chuck Harris

Jan J wrote:

I haven't seem many Tek Video Scope posts here, but from info I read here about Issues with a TEK 2465, I can tell you that I've successfully replaced a Dallas 1225 chip with Ramtron16W08 with Dip Header on a TEK 1760 Scope, and it works fine after the change out.
With the help of a Programmer that supported the 1225 chip, I saved stock Ram Contents to disk, then I also changed one location of the contents of the memory from 0 to F and with that changed re-programmed into the 1225 or 16W08, that allowed me to use a 1750 SCH Option Board in the 1760.
That location was 0F in the Ram contents... Changed 00 to 0F.
That, and some scope gain and config tweaks allowed me to Take a 1760 Scope, and add a SCH Option Removed from a 1750 Scope (with bad CRT). Prior to this memory 'poke' the SCH Option would not be activated when the SCH button was pressed......
Jan J
 

I did encounter just that....? But I got around it by telling the Programmer it was a 1225 chip and all was fine

On 12/5/2017 9:29 AM, Chuck Harris wrote:
The Ramtron 16W08 family works very well in the 2465A and B
as both a replacement for the Dallas 1225, and as a replacement
for the battery and CMOS RAM in the "A" and early "B" scopes.

However...

Be warned that some EPROM programmers don't prime the pump
correctly with the FRAM chips. The CS is an address latch signal,
not a simple bus enable as it is with most RAM chips. This can mean
that your first, and last address will be in error, even though each
additional address will be fine.

In the 2465A or B scopes, the NVRAM is used as both an area to store
constants, and as system RAM. The system RAM controls the first
addresses as part of the interrupt vector array, and as such it is
restored every time the scope is powered up. Other instruments may
not do this.

To make the FRAM chips work happily in a scope with a separate battery
and CMOS RAM, you have to modify the battery test circuitry to fool
it into thinking the battery is always good.

( Short CR2371 and CR2370, replace CR2770 with 3.9K resistor, remove
battery, jumper + pad to - pad, install label over battery footprint
disclosing modification.)

-Chuck Harris

Jan J wrote:
I haven't seem many Tek Video Scope posts here, but from info I read here about Issues with a TEK 2465, I can tell you that I've successfully replaced a Dallas 1225 chip with Ramtron16W08 with Dip Header on a TEK 1760 Scope, and it works fine after the change out.
With the help of a Programmer that supported the 1225 chip, I saved stock Ram Contents to disk, then I also changed one location of the contents of the memory from 0 to F and with that changed re-programmed into the 1225 or 16W08, that allowed me to use a 1750 SCH Option Board in the 1760.
That location was 0F in the Ram contents... Changed 00 to 0F.
That, and some scope gain and config tweaks allowed me to Take a 1760 Scope, and add a SCH Option Removed from a 1750 Scope (with bad CRT). Prior to this memory 'poke' the SCH Option would not be activated when the SCH button was pressed......
Jan J
 

Also, the Tek 1700 series relies on battery within 1225 only... no other battery...

On 12/5/2017 9:29 AM, Chuck Harris wrote:
The Ramtron 16W08 family works very well in the 2465A and B
as both a replacement for the Dallas 1225, and as a replacement
for the battery and CMOS RAM in the "A" and early "B" scopes.

However...

Be warned that some EPROM programmers don't prime the pump
correctly with the FRAM chips. The CS is an address latch signal,
not a simple bus enable as it is with most RAM chips. This can mean
that your first, and last address will be in error, even though each
additional address will be fine.

In the 2465A or B scopes, the NVRAM is used as both an area to store
constants, and as system RAM. The system RAM controls the first
addresses as part of the interrupt vector array, and as such it is
restored every time the scope is powered up. Other instruments may
not do this.

To make the FRAM chips work happily in a scope with a separate battery
and CMOS RAM, you have to modify the battery test circuitry to fool
it into thinking the battery is always good.

( Short CR2371 and CR2370, replace CR2770 with 3.9K resistor, remove
battery, jumper + pad to - pad, install label over battery footprint
disclosing modification.)

-Chuck Harris

Jan J wrote:
I haven't seem many Tek Video Scope posts here, but from info I read here about Issues with a TEK 2465, I can tell you that I've successfully replaced a Dallas 1225 chip with Ramtron16W08 with Dip Header on a TEK 1760 Scope, and it works fine after the change out.
With the help of a Programmer that supported the 1225 chip, I saved stock Ram Contents to disk, then I also changed one location of the contents of the memory from 0 to F and with that changed re-programmed into the 1225 or 16W08, that allowed me to use a 1750 SCH Option Board in the 1760.
That location was 0F in the Ram contents... Changed 00 to 0F.
That, and some scope gain and config tweaks allowed me to Take a 1760 Scope, and add a SCH Option Removed from a 1750 Scope (with bad CRT). Prior to this memory 'poke' the SCH Option would not be activated when the SCH button was pressed......
 

You got lucky, as the 1225 chip behaves exactly like
the CMOS RAM chip that it contains... a 6116 type.. Your
EPROM programmer happened to do it accidentally right. It
wasn't on purpose as the FRAM didn't exist until a decade
later.

The FRAM is different, its CS is used to latch the address
lines... not to simply enable the bus drivers.

-Chuck Harris

Jan J wrote:

I did encounter just that.... But I got around it by telling the Programmer it was a
1225 chip and all was fine


On 12/5/2017 9:29 AM, Chuck Harris wrote:
The Ramtron 16W08 family works very well in the 2465A and B
as both a replacement for the Dallas 1225, and as a replacement
for the battery and CMOS RAM in the "A" and early "B" scopes.

However...

Be warned that some EPROM programmers don't prime the pump
correctly with the FRAM chips. The CS is an address latch signal,
not a simple bus enable as it is with most RAM chips. This can mean
that your first, and last address will be in error, even though each
additional address will be fine.

In the 2465A or B scopes, the NVRAM is used as both an area to store
constants, and as system RAM. The system RAM controls the first
addresses as part of the interrupt vector array, and as such it is
restored every time the scope is powered up. Other instruments may
not do this.

To make the FRAM chips work happily in a scope with a separate battery
and CMOS RAM, you have to modify the battery test circuitry to fool
it into thinking the battery is always good.

( Short CR2371 and CR2370, replace CR2770 with 3.9K resistor, remove
battery, jumper + pad to - pad, install label over battery footprint
disclosing modification.)

-Chuck Harris
 

Obviously.

I was simply expanding on what you stated to include the early
2465B and 2465A. I can't say that I have ever run into the
1700 series.. Isn't it a vector scope, or something like that?

-Chuck Harris

Jan J wrote:

Also, the Tek 1700 series relies on battery within 1225 only... no other battery...


On 12/5/2017 9:29 AM, Chuck Harris wrote:
The Ramtron 16W08 family works very well in the 2465A and B
as both a replacement for the Dallas 1225, and as a replacement
for the battery and CMOS RAM in the "A" and early "B" scopes.

However...

Be warned that some EPROM programmers don't prime the pump
correctly with the FRAM chips. The CS is an address latch signal,
not a simple bus enable as it is with most RAM chips. This can mean
that your first, and last address will be in error, even though each
additional address will be fine.

In the 2465A or B scopes, the NVRAM is used as both an area to store
constants, and as system RAM. The system RAM controls the first
addresses as part of the interrupt vector array, and as such it is
restored every time the scope is powered up. Other instruments may
not do this.

To make the FRAM chips work happily in a scope with a separate battery
and CMOS RAM, you have to modify the battery test circuitry to fool
it into thinking the battery is always good.

( Short CR2371 and CR2370, replace CR2770 with 3.9K resistor, remove
battery, jumper + pad to - pad, install label over battery footprint
disclosing modification.)

-Chuck Harris
 

-CS does more than latch the address. Like DRAM, FRAM uses sense
amplifiers which must be precharged before each read operation. When
-CS is high, the sense amplifiers are precharged in preparation for
the next read operation.

On Tue, 5 Dec 2017 21:17:25 -0500, you wrote:

You got lucky, as the 1225 chip behaves exactly like
the CMOS RAM chip that it contains... a 6116 type.. Your
EPROM programmer happened to do it accidentally right. It
wasn't on purpose as the FRAM didn't exist until a decade
later.

The FRAM is different, its CS is used to latch the address
lines... not to simply enable the bus drivers.

-Chuck Harris
Jan J
 

Does Composite, Component Waveform and Vector/Diamond display.. Plus,? Time Code, Audio, and SCH.. SCH is an option board...

I don't know if this forum supports pictures... if it does, here is what a good SCH Display looks like.....

On 12/5/2017 9:21 PM, Chuck Harris wrote:
Obviously.

I was simply expanding on what you stated to include the early
2465B and 2465A. I can't say that I have ever run into the
1700 series.. Isn't it a vector scope, or something like that?

-Chuck Harris

Jan J wrote:
Also, the Tek 1700 series relies on battery within 1225 only... no other battery...


On 12/5/2017 9:29 AM, Chuck Harris wrote:
The Ramtron 16W08 family works very well in the 2465A and B
as both a replacement for the Dallas 1225, and as a replacement
for the battery and CMOS RAM in the "A" and early "B" scopes.

However...

Be warned that some EPROM programmers don't prime the pump
correctly with the FRAM chips. The CS is an address latch signal,
not a simple bus enable as it is with most RAM chips. This can mean
that your first, and last address will be in error, even though each
additional address will be fine.

In the 2465A or B scopes, the NVRAM is used as both an area to store
constants, and as system RAM. The system RAM controls the first
addresses as part of the interrupt vector array, and as such it is
restored every time the scope is powered up. Other instruments may
not do this.

To make the FRAM chips work happily in a scope with a separate battery
and CMOS RAM, you have to modify the battery test circuitry to fool
it into thinking the battery is always good.

( Short CR2371 and CR2370, replace CR2770 with 3.9K resistor, remove
battery, jumper + pad to - pad, install label over battery footprint
disclosing modification.)

-Chuck Harris

SCH.JPG

 

Tektronix was always good about sharing parts
and ideas among their product line. Looks to me
like it could share a lot in common with the
2465 family. Not bandwidth, so much, but certainly
CRT drive and control, CPU, front panel control
mechanisms...

I'm pretty sure that most anything that uses a 1225
would rely upon its battery, as that is the only way
it has of preserving data. The earlier 2465B, and the
2465A used a separate battery, control, and CMOS RAM
to provide non volatile storage.

Thanks for enlightening me.

-Chuck Harris

Jan J wrote:

Does Composite, Component Waveform and Vector/Diamond display.. Plus, Time Code,
Audio, and SCH.. SCH is an option board...

I don't know if this forum supports pictures... if it does, here is what a good SCH
Display looks like.....

On 12/5/2017 9:21 PM, Chuck Harris wrote:
Obviously.

I was simply expanding on what you stated to include the early
2465B and 2465A. I can't say that I have ever run into the
1700 series.. Isn't it a vector scope, or something like that?

-Chuck Harris

Jan J wrote:
Also, the Tek 1700 series relies on battery within 1225 only... no other battery...
 

When I changed the Dallas NVSRAMs in my 2440, I did some experiments
to see if they could be used as low power battery backed up SRAMs by
maintaining the supply voltage above the point where the internal
battery would discharge but below the point where the NVSRAMs would be
active. There was no such point and the supply current required would
have been way too high to use an external battery for more than weeks
to months.

My backup plan was to restore the original design with the separate
battery, control, and low power SRAM. At least on the 2440, the
printed circuit boards were the same but the parts were changed or
removed.

As it ended up, the Cypress STK16C88 EEPROM based NVSRAMs that I used
were drop in replacements and worked perfectly so I did not get to
trying FRAM.

On Wed, 6 Dec 2017 07:51:56 -0500, you wrote:

Tektronix was always good about sharing parts
and ideas among their product line. Looks to me
like it could share a lot in common with the
2465 family. Not bandwidth, so much, but certainly
CRT drive and control, CPU, front panel control
mechanisms...

I'm pretty sure that most anything that uses a 1225
would rely upon its battery, as that is the only way
it has of preserving data. The earlier 2465B, and the
2465A used a separate battery, control, and CMOS RAM
to provide non volatile storage.

Thanks for enlightening me.

-Chuck Harris
 

One of my customer's 2465B's was really a 2445B, ala the
ebay guy's handiwork. It was an early model that had the
CMOS RAM and a battery. The handyman removed the CMOS RAM,
left the battery and all of its support circuitry in place,
and replaced the RAM with a 1225. I guess his idea was that
the battery would keep the alert off until the warranty
expired. I suppose it is possible he was just asleep when
he did the work too...

Well, the DS chip really hated having its power stuck at 3.6V,
which was a brown out state, and it drew about 0.1ma from VCC
in that condition. The DS died early, the battery died, and
a new calibration was in order.

I think that was the first scope I converted to an FRAM.

-Chuck Harris

David Hess wrote:

When I changed the Dallas NVSRAMs in my 2440, I did some experiments
to see if they could be used as low power battery backed up SRAMs by
maintaining the supply voltage above the point where the internal
battery would discharge but below the point where the NVSRAMs would be
active. There was no such point and the supply current required would
have been way too high to use an external battery for more than weeks
to months.

My backup plan was to restore the original design with the separate
battery, control, and low power SRAM. At least on the 2440, the
printed circuit boards were the same but the parts were changed or
removed.

As it ended up, the Cypress STK16C88 EEPROM based NVSRAMs that I used
were drop in replacements and worked perfectly so I did not get to
trying FRAM.

On Wed, 6 Dec 2017 07:51:56 -0500, you wrote:

Tektronix was always good about sharing parts
and ideas among their product line. Looks to me
like it could share a lot in common with the
2465 family. Not bandwidth, so much, but certainly
CRT drive and control, CPU, front panel control
mechanisms...

I'm pretty sure that most anything that uses a 1225
would rely upon its battery, as that is the only way
it has of preserving data. The earlier 2465B, and the
2465A used a separate battery, control, and CMOS RAM
to provide non volatile storage.

Thanks for enlightening me.

-Chuck Harris
Jan J
 

When I found the SCH option board from a 1750 scope, I contacted Tek to see if it was a 'drop in' replacement. They said 'Yes'.. Really it's "NO"

I was then given some software (DOS) that would 'calibrate'---- a nearly 70 step program that would Create the BBRAM settings for this scope-If you had to replace the BBRAM chip.

With a new 1225 chip, I practiced--repeatedly with the program, and I got pretty good at setting up Waveform and Vector display, but I had no component signals to use, and it didn't cover the SCH Option board I was trying to install during the calibrate program, nor after I was done with calibrate and stored the settings to the BBRAM... SCH Option (When I hit the button) did not work....

By this time I was communicating with a thread at TEK,? and I kept revisiting the subject of: How can I ENABLE the SCH Option?? The 3 or so people that did reply from that thread, were continually referencing to "1760SC"?? Which I could not find in the software I received from them....? During this time I was also attempting to upgrade from V2.3 to V2.4 firmware in the scope, as one of them said that would do it... but? the Upgrade software sent would not erase the NVRAM....

Finally, a fellow who had never replied to me from work, did so from home, and pointed me to a TEK U.K. site where the same software that I had been sent before was posted in a public download.... I downloaded it and found out that it was a LATER version of the same software sent to me before, but this one had 80 steps in the CAL Program, and? included references to a "SCOPE BUILD" Document, and covered all the 1700 scope family, and a reference to a TEK Document? "See PRC_LANG.DOC for instructions on building Model, Option, and Title codes from the key...." and the following information:
01 NTSC
02 PAL
04 DUAL
10 MISC STEPS (Main Board)
20 VECTOR BOARD
40 SCH BOARD
80 COMPONENT BOARD
and a rem statement of the? models:
TEK1740A ? 31
TEK 1741A? 32
TEK1745A?? 34
TEK 1750A? 71
TEK 1751A? 72
TEK 1755A? 74
TEK 1760???? B1
TEK1761????? B2
TEK 1765??? B4
TEK 1760SC F1
TEK1761SC? F2
TEK1765SC? F4

Armed with this information, I contacted everyone at TEK that I had contacted before, asking for the PRC_LANG.DOC.....
At this point, ALL Communications with the folks on that support Link STOPPED!!!!
After waiting a week... I did an online chat... and was abruptly told I would NOT Get that document.... and demanded to know how I found out about it?
"Well, it's a remark statement within the software you released to the public"
The chat link abruptly ended....? !!!
I then called Support, and was told that that document: PRC_LANG.DOC was a COMPANY DOCUMENT for Company Personnel only.... and I will never get it...
That was the end of my support ---- Support!!!?? I was officially on my own...

By this time, I had a couple spare 1225 chips, and was awaiting the Ramtoron 16W08 on a DIP Header...? and started "doing experiments" to see if I could find a way to Enable the SCH board from 1750 scope in my 1760 scope...? and I in-advertantly powered up scope WITHOUT the 1225 in the socket, and though the gain calibrations were incorrect---SCH OPTION BOARD WORKED!!!!
I then purchased a Programmer, read the contents of "stock" 1225 chip, and then by using 'Powers of 2'? I put "F" in the first half of BBRAM contents, and put that in scope... SCH WORKED!
So I then walked the "F" back until I found the ONE LOCATION (Address 0F) where an "F" would allow me to use the SCH Option.... With this (by then Ramtron chip on Dip Header arrived), I then touched up some gains, and scope was good except for SCH Gain on CRT..... (For some reason--1750 SCH Option board in 1760 scope with Firmware Hack to enable SCH Option board would not adjust SCH Gain in the updated CAL Program the guy pointed me to in the U.K.)?? I fixed this by putting a 200K pot in place of R145 (33.2K).... and adjusting SCH Gain....

So, even though TEK Said it would be Plug and Play.... It sure as hell wasn't.... and I had to HACK the BBRAM in order to enable the SCH Option board from a 1750 scope to work in a 1760 scope....

Sorry for being so wordy.... but what? a? "Long, Strange Trip this has been!!!"
Jan





On 12/6/2017 7:51 AM, Chuck Harris wrote:
Tektronix was always good about sharing parts and ideas among their > product line. Looks to me like it could share a lot in common with >
the 2465 family. Not bandwidth, so much, but certainly CRT drive and > control, CPU, front panel control mechanisms... > > I'm pretty sure that most anything that uses a 1225 would rely upon > its battery, as that is the only way it has of preserving data. The > earlier 2465B, and the 2465A used a separate battery, control, and > CMOS RAM to provide non volatile storage. > > Thanks for enlightening me. > > -Chuck Harris > > Jan J wrote: >> Does Composite, Component Waveform and Vector/Diamond display.. >> Plus, Time Code, Audio, and SCH.. SCH is an option board...
I don't know if this forum supports pictures... if it does, here
is >> what a good SCH Display looks like..... >> >> On 12/5/2017 9:21 PM, Chuck Harris wrote: >>> Obviously. >>> >>> I was simply expanding on what you stated to include the early >>> 2465B and 2465A. I can't say that I have ever run into the 1700 >>> series.. Isn't it a vector scope, or something like that? >>> >>> -Chuck Harris >>> >>> Jan J wrote: >>>> Also, the Tek 1700 series relies on battery within 1225 only... >>>> no other battery... > > >
 

Hi Jan,

That is truly strange. Are the later models 176xSC still under
Tek support?

And I suppose it is possible that there was some customer proprietary
information in that setup program that may have triggered their
sudden reluctance to share further information.... NSA comes to mind.

Anyway, it sounds like your hard work paid off.

-Chuck Harris

Jan J wrote:
When I found the SCH option board from a 1750 scope, I contacted Tek to see if it was
a 'drop in' replacement. They said 'Yes'.. Really it's "NO"

I was then given some software (DOS) that would 'calibrate'---- a nearly 70 step
program that would Create the BBRAM settings for this scope-If you had to replace the
BBRAM chip.

With a new 1225 chip, I practiced--repeatedly with the program, and I got pretty good
at setting up Waveform and Vector display, but I had no component signals to use, and
it didn't cover the SCH Option board I was trying to install during the calibrate
program, nor after I was done with calibrate and stored the settings to the BBRAM...
...
Jan J
 

I started this project about 4-5 months ago....

The reasons for adding SCH Option are as strange as the trip I took getting it to work... I am a retired TV Maintenance Engineer... (ABC). Also a Video Hobbyist.

I was given some old broadcast gear that would improve video capturing, and it could use a Genlock Reference Signal to 'lock' all devices to a common reference.

I had a black generator on shelf for years, that I had never used... and when I did use it... Captures started failing... coming out in 'Reverse Field Dominance' in SD and 1080i HD... I got around the problem by purchasing another black generator... That did work....?? But I wanted to know WHY did the first Black Generator cause the failures in Field Dominance????? I'm Nosy that way!!! :)!

The 1760 scope I had did not 'see' anything wrong, and I suspected SCH error might be the cause, but I had no way of measuring that.... (SCH is the phase of Color Burst compared to Leading Edge of Horizontal Sync in Composite signals).....

I contacted TEK Support and asked if a 1750SCH Option board would work in a 1760 Scope, and they said "YES".? Armed with this, I started looking for an SCH Option board... Since TEK told me it would work.... (Ha-Ha!)

I eventually came across a 1750 scope that had a bad CRT, but the fellow was willing to trade me the SCH Option board out of it, if I captured HD Video off his HD Tape machine and? made a BluRay Disk of it for him...

Armed with the Option board, I put it in the 1760 scope, and it would not enable from the SCH Button on the front panel......


And That's where this project began!!!!!


OH YES!!!? SCH measurements on that Black Generator revealed there was Great JITTER on the SCH measurements... Jitter that was not 'seen' on 1760 Waveform or Vector display.... Jitter that only could be seen by an SCH Measurement!!!

I took that Black Generator with bad SCH to the local Dump, and just happened to be there when they were shredding TV's in a great grinder.... I told the operator why I was there, and asked if I could personally pitch this generator in the shredder, and he said "Go For It!!!" .....


That Generator is now in hundreds of thousands of pieces, and will never cause 'Reverse Field Dominance'? Ever again!!!!

Jan

On 12/7/2017 8:03 AM, Chuck Harris wrote:
Hi Jan,

That is truly strange. Are the later models 176xSC still under
Tek support?

And I suppose it is possible that there was some customer proprietary
information in that setup program that may have triggered their
sudden reluctance to share further information.... NSA comes to mind.

Anyway, it sounds like your hard work paid off.

-Chuck Harris

Jan J wrote:
When I found the SCH option board from a 1750 scope, I contacted Tek to see if it was
a 'drop in' replacement. They said 'Yes'.. Really it's "NO"

I was then given some software (DOS) that would 'calibrate'---- a nearly 70 step
program that would Create the BBRAM settings for this scope-If you had to replace the
BBRAM chip.

With a new 1225 chip, I practiced--repeatedly with the program, and I got pretty good
at setting up Waveform and Vector display, but I had no component signals to use, and
it didn't cover the SCH Option board I was trying to install during the calibrate
program, nor after I was done with calibrate and stored the settings to the BBRAM...
...

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