Re: 2465A/B Calibration Restoration for A or early B...
Success! I did the Cal 05 routine and exited without changing anything. Scope booted up
normally without the error!
So everything is back to normal. Thank you Mark, Chris and Chuck for the time and effort
you guys expended on this project. This will be useful to a lot of folks in a similar situation.
Don
|
Re: 2465A/B Calibration Restoration for A or early B...
Mark,
I will give that a try as soon?as I get home from work. That sounds promising!
On Friday, April 19, 2024, 11:28 AM, Mark Litwack <mark@...> wrote: Ok, after some additional experimenting...
I made a wrong assumption that the ON/OFF count and/or the power on
cycles was included in the checksum that I was watching at EXER 02
location 0000.? They do not seem to be included since the checksum
never changed.
Here's a better test.? I placed a bad checksum value at 0000 and
verified the scope now had a TEST 04 FAIL 10 (bad checksum) on boot.
Then, going into CAL 05 and getting out without changing anything, the
scope rewrote the checksum back to the correct value.? Subsequent
boots had no error.
Don: Can you give CAL 05 a try?
-mark
On Fri, 19 Apr 2024 11:35:05 -0400
> Hi Victor,
>
> That was the first thing I tried.? The checksum is at EXER 02 address
> 0000.? Changing the ON/OFF count or hours does not change the checksum
> location.
>
> I don't know all the details of the implementation and I suppose it's
> possible that 0000 is only a checksum for the cal data and not other
> operating data.
>
> It certainly won't hurt if Don can try it.
>
> (Actually, nothing will hurt since he can put it all back anyway.)
>
> -mark
>
>
>
> On Fri, 19 Apr 2024 05:33:08 -0700
> "victor.silva via groups.io" <daejon1@...> wrote:
> > Mark,
> >
> > I believe if you make a small change to the ON TIME or ON/OFF counter in CAL 05 it will refresh the checksum.
> >
> > --Victor?
>
>
>
>
>
|
Re: 2465A/B Calibration Restoration for A or early B...
Ok, after some additional experimenting... I made a wrong assumption that the ON/OFF count and/or the power on cycles was included in the checksum that I was watching at EXER 02 location 0000. They do not seem to be included since the checksum never changed. Here's a better test. I placed a bad checksum value at 0000 and verified the scope now had a TEST 04 FAIL 10 (bad checksum) on boot. Then, going into CAL 05 and getting out without changing anything, the scope rewrote the checksum back to the correct value. Subsequent boots had no error. Don: Can you give CAL 05 a try? -mark On Fri, 19 Apr 2024 11:35:05 -0400 "Mark Litwack" <mark@...> wrote: Hi Victor,
That was the first thing I tried. The checksum is at EXER 02 address
0000. Changing the ON/OFF count or hours does not change the checksum
location.
I don't know all the details of the implementation and I suppose it's
possible that 0000 is only a checksum for the cal data and not other
operating data.
It certainly won't hurt if Don can try it.
(Actually, nothing will hurt since he can put it all back anyway.)
-mark
On Fri, 19 Apr 2024 05:33:08 -0700
"victor.silva via groups.io" <daejon1@...> wrote:
Mark,
I believe if you make a small change to the ON TIME or ON/OFF counter in CAL 05 it will refresh the checksum.
--Victor
|
Re: 2465A/B Calibration Restoration for A or early B...
Hi Victor, That was the first thing I tried. The checksum is at EXER 02 address 0000. Changing the ON/OFF count or hours does not change the checksum location. I don't know all the details of the implementation and I suppose it's possible that 0000 is only a checksum for the cal data and not other operating data. It certainly won't hurt if Don can try it. (Actually, nothing will hurt since he can put it all back anyway.) -mark On Fri, 19 Apr 2024 05:33:08 -0700 "victor.silva via groups.io" <daejon1@...> wrote: Mark,
I believe if you make a small change to the ON TIME or ON/OFF counter in CAL 05 it will refresh the checksum.
--Victor
|
Re: 2465A/B Calibration Restoration for A or early B...
On Friday (04/19/2024 at 05:33AM -0700), victor.silva via groups.io wrote: Mark,
I believe if you make a small change to the ON TIME or ON/OFF counter in CAL 05 it will refresh the checksum. I had the same theory-- adjust one of the calibration values and it will have to recompute the checksum. I suggested changing one slightly, exiting CAL, then go back in and change it back to the correct/desired value. So glad you guys were able to put the constants back. Chuck and I were basically recreating work done in 2018, because we didn't know it had been done already. Is that like a double-blind taste test then or ?? :-) Good work in any case, Chris -- Chris Elmquist
|
Re: 2465A/B Calibration Restoration for A or early B...
Mark,
I believe if you make a small change to the ON TIME or ON/OFF counter in CAL 05 it will refresh the checksum.
--Victor
|
Re: 2465A/B Calibration Restoration for A or early B...
The information is unknown to me. I assure you that 100% of what you need is in the EXER 02 data. You must transcribe it correctly, however. It is really easy to get 8's and B's mixed up. Great job Mark! -Chuck Harris On Thu, 18 Apr 2024 20:55:35 -0400 "Mark Litwack" <mark@...> wrote: Hi Chuck and Chris,
I was recently alerted to this thread by Don. A lot of this memory
mapping stuff has already been figured out. You might find these
posts useful:
https://www.eevblog.com/forum/testgear/just-got-a-2465a-couple-questions/msg1469675/#ms\
g1469675
https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg4750262\
/#msg4750262
I've developed code which re-initializes the cal data area in the SRAM
to the EXER 02 data provided by the user. It works on a 2445A that
I've been using for testing. It has worked for Don on his 2467B, but
there is a still a checksum error that needs to be investigated (TEST
04 FAIL 10). No parity errors.
The checksum is stored at location 0000 in EXER 02's view. I am not
sure what the scope is including in its checksum, but I'm thinking if
the scope could be forced to recalculate the checksum, all will be
well.
Do you know how to make the scope re-calculate the checksum and store
it in the NVRAM (short of performing a re-cal)?
-mark
|
Re: Help! I bricked a perfectly functioning 2467B!
Since I have personally written the EXER 02 data into a blank NVRAM, and gotten perfect results, my only conclusion is you made a transcription error with the/your EXER 02 data. It is essential that all 170 of the calibration bytes be copied exactly, or some part of the calibration will be irretrievably lost. Mark, take a bow! -Chuck Harris On Thu, 18 Apr 2024 16:04:35 -0700 "Don via groups.io" <donald_s_58103@...> wrote: Here is an update. I had posted this over on the Tekscopes Forum and
Mark Litwack was also working on a solution and I am happy to report
that his code has successfully written back the cal data to my scope
and the scope functions just like it did before the mishap with the
battery replacement.
The only remaining issue is that I still get a "TEST 04 FAIL 10"
error message on startup, but when I clear it with the A/B trigger
button, the scope functions normally without the ????? marks at the
bottom of the screen. I also checked all the calibration data and it
matches the one I had recorded with EXER 02 routine before I did the
battery replacement.
Before going the route of writing the cal data back to RAM, very
early on after I developed the problem with my scope, based on
someone's recommendation, I thought I would do the Automatic
Calibration routine starting on page 5-12 of the service manual.
However, after I started it, I decided against it and quit the
routine. I did not change anything. I wonder if doing this changed
the original checksum and that has something to do with it?
Don
|
Re: 2465A/B Calibration Restoration for A or early B...
Hi Chuck and Chris, I was recently alerted to this thread by Don. A lot of this memory mapping stuff has already been figured out. You might find these posts useful: https://www.eevblog.com/forum/testgear/just-got-a-2465a-couple-questions/msg1469675/#ms\g1469675 https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg4750262\/#msg4750262 I've developed code which re-initializes the cal data area in the SRAM to the EXER 02 data provided by the user. It works on a 2445A that I've been using for testing. It has worked for Don on his 2467B, but there is a still a checksum error that needs to be investigated (TEST 04 FAIL 10). No parity errors. The checksum is stored at location 0000 in EXER 02's view. I am not sure what the scope is including in its checksum, but I'm thinking if the scope could be forced to recalculate the checksum, all will be well. Do you know how to make the scope re-calculate the checksum and store it in the NVRAM (short of performing a re-cal)? -mark
|
Re: Help! I bricked a perfectly functioning 2467B!
Here is an update. I had posted this over on the Tekscopes Forum and Mark Litwack was also working
on a solution and I am happy to report that his code has successfully written back the cal data to
my scope and the scope functions just like it did before the mishap with the battery replacement.
The only remaining issue is that I still get a "TEST 04 FAIL 10" error message on startup, but when I clear it
with the A/B trigger button, the scope functions normally without the ????? marks at the bottom of
the screen. I also checked all the calibration data and it matches the one I had recorded with EXER 02
routine before I did the battery replacement.
Before going the route of writing the cal data back to RAM, very early on after I developed the problem
with my scope, based on someone's recommendation, I thought I would do the Automatic Calibration
routine starting on page 5-12 of the service manual. However, after I started it, I decided against it
and quit the routine. I did not change anything. I wonder if doing this changed the original checksum and
that has something to do with it?
Don
|
Good, the CCFL tubes are rated perhaps 5000 hours, the LEDS are effectively infinite, and lots easier to deal with.
Harvey
toggle quoted message
Show quoted text
On 4/16/2024 5:28 PM, Zack Widup wrote: Thanks Harvey. I figured out how to measure the output voltages by pushing wires into the socket connector pins on the output of the 121PW181 module. I also found a manual for that module. It appears all the voltages on the input are correct for operation of the module. But the output voltages are 0 volts AC. Also, the ends of the FLD tubes are also slightly discolored.
I ordered this kit:
<>
This appears to be a replacement kit, but using LED's instead of the FLD tube.
Zack
On Tue, Apr 16, 2024 at 2:54?PM Harvey White via groups.io <> <madyn@...> wrote:
re: measuring the voltages:?? DON'T unless you like 1500 volts.
That's
about 1000 volts at about 3-5 ma.? Definitely enough to be highly
dangerous.
The backlights are CCFL lamps, evacuated tubes with some mercury in
them.? They work like standard fluorescent lamps without a heater.
If the lamps show signs of darkening, they are likely suspect.
Unless you have a high voltage AC probe, (for a scope), don't do
anything with them.
There are some low voltage LED replacement kits on the market.
There are also replacement lamps available, specific to that display,
I'd think.
One thing to do is to take a scope probe and see if you can pick
up? a
magnetic field (use a small loop of insulated wire) by getting
NEAR the
inverter transformer.? Another is to see how much low voltage current
you're pulling.? It might be a bit.
Inverters can also be had.
Another trick might be to get an ungrounded neon lamp (plastic
rod! for
a handle) near the HV lines, or near the transformer.
Yet another would be to expose enough of the lamps (when installed in
the display), run the equipment in darkness, and see if you can
see any
light from the tubes.? Keep your distance from the tubes, though
and the
inverter.? There's a reason why the inverter has a nice coating of
insulating epoxy on it.
Be careful.
Harvey
On 4/16/2024 3:18 PM, Zack Widup wrote:
> Thanks. The backlight consists of two very small diameter glass
tubes
> about 10 inches long and somewhere around 1/16 inch in diameter.
There
> are two pink wires and one yellow wire coming out of that
assembly and
> going to a plug on a board that appears to be a high-voltage power
> supply. The power supply board is even labeled "high voltage." I
don't
> think that is an LED backlight. The pc board patterns going from a
> module on the power supply board are covered with epoxy up to the
> connector. I cannot figure out a way to measure the voltages out of
> the connector to the pink and yellow wires without cutting the
wires.
>
> Zack
>
> On Tue, Apr 16, 2024 at 1:45?PM dan.meeks222@... via
groups.io <>
> <> <dan.meeks222@...> wrote:
>
>? ? ?That probably uses LED backlighting, and that may have a
separate
>? ? ?power connector. So look for that¡
>
>? ? ?I doubt it¡¯s got the old CCFL backlight, but that would
certainly
>? ? ?be a separate connector as the voltage is too high to
include with
>? ? ?signals.
>
>? ? ?Good luck and keep us posted.
>
>? ? ?dan
>
>? ? ?*From:*[email protected] <[email protected]> *On Behalf Of
>? ? ?*Zack Widup via groups.io <> <>
>? ? ?*Sent:* Tuesday, April 16, 2024 1:42 PM
>? ? ?*To:* [email protected]
>? ? ?*Subject:* [TekScopes2] DPO70804
>
>? ? ?I have a DPO70804 scope. The display is dark. I have determined
>? ? ?that the fluorescent backlight tubes are not lit. I connected an
>? ? ?XGA monitor to the XGA socket on the rear, and the XGA monitor
>? ? ?displays the scope display and all functions are working
correctly.
>
>? ? ?I have been trying to determine if the display tubes or the
>? ? ?voltage supply for those tubes is bad, or if the problem is
>? ? ?elsewhere. The service manual I have for the unit contains no
>? ? ?schematics nor any info on a way to test the fluorescent display
>? ? ?circuit.
>
>? ? ?The power supply board has a 20-pin plug with voltages on the
>? ? ?pins. All the voltages are correct as per a drawing in the
manual,
>? ? ?except for the -5 volt pin (pin 18). That measures 0 volts.
But on
>? ? ?the drawing, there is an asterisk next to the -5 volt pin,
with no
>? ? ?explanation I can find anywhere of what the asterisk means. The
>? ? ?PS-ON pin measures 0 volts and the PW-OK pin measures +5 volts.
>
>? ? ?Can anybody give me any guidance or suggestions?
>
>? ? ?Zack
>
>
|
Thanks Harvey. I figured out how to measure the output voltages by pushing wires into the socket connector pins on the output of the 121PW181 module. I also found a manual for that module. It appears all the voltages on the input are correct for operation of the module. But the output voltages are 0 volts AC. Also, the ends of the FLD tubes are also slightly discolored.
I ordered this kit:
This appears to be a replacement kit, but using LED's instead of the FLD tube.
Zack
|
|
?
re: measuring the voltages:?? DON'T unless you like 1500 volts. That's
about 1000 volts at about 3-5 ma.? Definitely enough to be highly dangerous.
The backlights are CCFL lamps, evacuated tubes with some? mercury in
them.? They work like standard fluorescent lamps without a heater.
If the lamps show signs of darkening, they are likely suspect.
Unless you have a high voltage AC probe, (for a scope), don't do
anything with them.
There are some low voltage LED replacement kits on the market.
There are also replacement lamps available, specific to that display,
I'd think.
One thing to do is to take a scope probe and see if you can? pick up? a
magnetic field (use a small loop of insulated wire) by getting NEAR the
inverter transformer.? Another is to see how much low voltage current
you're pulling.? It might be a bit.
Inverters can also be had.
Another trick might be to get an ungrounded neon lamp (plastic rod! for
a handle) near the HV lines, or near the transformer.
Yet another would be to expose enough of the lamps (when installed in
the display), run the equipment in darkness, and see if you can see any
light from the tubes.? Keep your distance from the tubes, though and the
inverter.? There's a reason why the inverter has a nice coating of
insulating epoxy on it.
Be careful.
Harvey
On 4/16/2024 3:18 PM, Zack Widup wrote:
> Thanks. The backlight consists of two very small diameter glass tubes
> about 10 inches long and somewhere around 1/16 inch in diameter. There
> are two pink wires and one yellow wire coming out of that assembly and
> going to a plug on a board that appears to be a high-voltage power
> supply. The power supply board is even labeled "high voltage." I don't
> think that is an LED backlight. The pc board patterns going from a
> module on the power supply board are covered with epoxy up to the
> connector. I cannot figure out a way to measure the voltages out of
> the connector to the pink and yellow wires without cutting the wires.
>
> Zack
>
> On Tue, Apr 16, 2024 at 1:45?PM dan.meeks222@... via
> <> <dan.meeks222=[email protected]> wrote:
>
>? ? ?That probably uses LED backlighting, and that may have a separate
>? ? ?power connector. So look for that¡
>
>? ? ?I doubt it¡¯s got the old CCFL backlight, but that would certainly
>? ? ?be a separate connector as the voltage is too high to include with
>? ? ?signals.
>
>? ? ?Good luck and keep us posted.
>
>? ? ?dan
>
>? ? ?*From:*[email protected] <[email protected]> *On Behalf Of
>? ? ?*Zack Widup via <>
>? ? ?*Sent:* Tuesday, April 16, 2024 1:42 PM
>? ? ?*To:* [email protected]
>? ? ?*Subject:* [TekScopes2] DPO70804
>
>? ? ?I have a DPO70804 scope. The display is dark. I have determined
>? ? ?that the fluorescent backlight tubes are not lit. I connected an
>? ? ?XGA monitor to the XGA socket on the rear, and the XGA monitor
>? ? ?displays the scope display and all functions are working correctly.
>
>? ? ?I have been trying to determine if the display tubes or the
>? ? ?voltage supply for those tubes is bad, or if the problem is
>? ? ?elsewhere. The service manual I have for the unit contains no
>? ? ?schematics nor any info on a way to test the fluorescent display
>? ? ?circuit.
>
>? ? ?The power supply board has a 20-pin plug with voltages on the
>? ? ?pins. All the voltages are correct as per a drawing in the manual,
>? ? ?except for the -5 volt pin (pin 18). That measures 0 volts. But on
>? ? ?the drawing, there is an asterisk next to the -5 volt pin, with no
>? ? ?explanation I can find anywhere of what the asterisk means. The
>? ? ?PS-ON pin measures 0 volts and the PW-OK pin measures +5 volts.
>
>? ? ?Can anybody give me any guidance or suggestions?
>
>? ? ?Zack
>
>
|
There's a fair amount of difference in CCFL voltages depending on the size of the tubes.
If the OP doesn't want to play with high voltages (and those are nasty!), then I'd look for a replacement LED strip made for that display.? It would come with a control board.
The current through the CCFL lamps is limited by the driver and board circuitry, so the board is matched to the lamps.
Harvey
toggle quoted message
Show quoted text
On 4/16/2024 3:26 PM, dan.meeks222@... wrote:
Okay yes so that¡¯s a CCFL (cold cathode fluorescent) backlight.
You will most likely find the backlight driver on a separate board (because of high voltage AND noise).
CCFL initially goes up to a high ¡°strike¡± voltage, then after the tube conducts the voltage drops. And it¡¯s AC voltage, keep that in mind if you try to measure it.
The CCFL driver may shut down if it detects that the tubes do not fire. But most likely that driver has fried.
I guess make sure the driver has DC input power, and maybe look for AC voltage on the output when you apply power. It¡¯s not 60Hz, so keep that in mind. Your DMM may or may not give you an accurate reading.
You can buy generic CCFL drivers but of course OEM is best if you can get it. Maybe Tek still sells it?
If you need to use a generic driver, try to find someone on the group that knows what voltage you need. I don¡¯t know if there is much difference in CCFL voltages.
Dan
*From:*[email protected] <[email protected]> *On Behalf Of *Zack Widup via groups.io
*Sent:* Tuesday, April 16, 2024 2:19 PM
*To:* [email protected]
*Subject:* Re: [TekScopes2] DPO70804
Thanks. The backlight consists of two very small diameter glass tubes about 10 inches long and somewhere around 1/16 inch in diameter. There are two pink wires and one yellow wire coming out of that assembly and going to a plug on a board that appears to be a high-voltage power supply. The power supply board is even labeled "high voltage." I don't think that is an LED backlight. The pc board patterns going from a module on the power supply board are covered with epoxy up to the connector. I cannot figure out a way to measure the voltages out of the connector to the pink and yellow wires without cutting the wires.
Zack
On Tue, Apr 16, 2024 at 1:45?PM dan.meeks222@... via groups.io <> <dan.meeks222@...> wrote:
That probably uses LED backlighting, and that may have a separate
power connector. So look for that¡
I doubt it¡¯s got the old CCFL backlight, but that would certainly
be a separate connector as the voltage is too high to include with
signals.
Good luck and keep us posted.
dan
*From:*[email protected] <[email protected]> *On Behalf Of
*Zack Widup via groups.io <>
*Sent:* Tuesday, April 16, 2024 1:42 PM
*To:* [email protected]
*Subject:* [TekScopes2] DPO70804
I have a DPO70804 scope. The display is dark. I have determined
that the fluorescent backlight tubes are not lit. I connected an
XGA monitor to the XGA socket on the rear, and the XGA monitor
displays the scope display and all functions are working correctly.
I have been trying to determine if the display tubes or the
voltage supply for those tubes is bad, or if the problem is
elsewhere. The service manual I have for the unit contains no
schematics nor any info on a way to test the fluorescent display
circuit.
The power supply board has a 20-pin plug with voltages on the
pins. All the voltages are correct as per a drawing in the manual,
except for the -5 volt pin (pin 18). That measures 0 volts. But on
the drawing, there is an asterisk next to the -5 volt pin, with no
explanation I can find anywhere of what the asterisk means. The
PS-ON pin measures 0 volts and the PW-OK pin measures +5 volts.
Can anybody give me any guidance or suggestions?
Zack
|
re: measuring the voltages:?? DON'T unless you like 1500 volts. That's about 1000 volts at about 3-5 ma.? Definitely enough to be highly dangerous.
The backlights are CCFL lamps, evacuated tubes with some? mercury in them.? They work like standard fluorescent lamps without a heater.
If the lamps show signs of darkening, they are likely suspect.
Unless you have a high voltage AC probe, (for a scope), don't do anything with them.
There are some low voltage LED replacement kits on the market.
There are also replacement lamps available, specific to that display, I'd think.
One thing to do is to take a scope probe and see if you can? pick up? a magnetic field (use a small loop of insulated wire) by getting NEAR the inverter transformer.? Another is to see how much low voltage current you're pulling.? It might be a bit.
Inverters can also be had.
Another trick might be to get an ungrounded neon lamp (plastic rod! for a handle) near the HV lines, or near the transformer.
Yet another would be to expose enough of the lamps (when installed in the display), run the equipment in darkness, and see if you can see any light from the tubes.? Keep your distance from the tubes, though and the inverter.? There's a reason why the inverter has a nice coating of insulating epoxy on it.
Be careful.
Harvey
toggle quoted message
Show quoted text
On 4/16/2024 3:18 PM, Zack Widup wrote: Thanks. The backlight consists of two very small diameter glass tubes about 10 inches long and somewhere around 1/16 inch in diameter. There are two pink wires and one yellow wire coming out of that assembly and going to a plug on a board that appears to be a high-voltage power supply. The power supply board is even labeled "high voltage." I don't think that is an LED backlight. The pc board patterns going from a module on the power supply board are covered with epoxy up to the connector. I cannot figure out a way to measure the voltages out of the connector to the pink and yellow wires without cutting the wires.
Zack
On Tue, Apr 16, 2024 at 1:45?PM dan.meeks222@... via groups.io <> <dan.meeks222@...> wrote:
That probably uses LED backlighting, and that may have a separate
power connector. So look for that¡
I doubt it¡¯s got the old CCFL backlight, but that would certainly
be a separate connector as the voltage is too high to include with
signals.
Good luck and keep us posted.
dan
*From:*[email protected] <[email protected]> *On Behalf Of
*Zack Widup via groups.io <>
*Sent:* Tuesday, April 16, 2024 1:42 PM
*To:* [email protected]
*Subject:* [TekScopes2] DPO70804
I have a DPO70804 scope. The display is dark. I have determined
that the fluorescent backlight tubes are not lit. I connected an
XGA monitor to the XGA socket on the rear, and the XGA monitor
displays the scope display and all functions are working correctly.
I have been trying to determine if the display tubes or the
voltage supply for those tubes is bad, or if the problem is
elsewhere. The service manual I have for the unit contains no
schematics nor any info on a way to test the fluorescent display
circuit.
The power supply board has a 20-pin plug with voltages on the
pins. All the voltages are correct as per a drawing in the manual,
except for the -5 volt pin (pin 18). That measures 0 volts. But on
the drawing, there is an asterisk next to the -5 volt pin, with no
explanation I can find anywhere of what the asterisk means. The
PS-ON pin measures 0 volts and the PW-OK pin measures +5 volts.
Can anybody give me any guidance or suggestions?
Zack
|
Okay yes so that¡¯s a CCFL (cold cathode fluorescent) backlight. You will most likely find the backlight driver on a separate board (because of high voltage AND noise). CCFL initially goes up to a high ¡°strike¡± voltage, then after the tube conducts the voltage drops. And it¡¯s AC voltage, keep that in mind if you try to measure it. The CCFL driver may shut down if it detects that the tubes do not fire. But most likely that driver has fried. I guess make sure the driver has DC input power, and maybe look for AC voltage on the output when you apply power. It¡¯s not 60Hz, so keep that in mind. Your DMM may or may not give you an accurate reading. You can buy generic CCFL drivers but of course OEM is best if you can get it. Maybe Tek still sells it? If you need to use a generic driver, try to find someone on the group that knows what voltage you need. I don¡¯t know if there is much difference in CCFL voltages. Dan ?
toggle quoted message
Show quoted text
From: [email protected] <[email protected]> On Behalf Of Zack Widup via groups.io
Sent: Tuesday, April 16, 2024 2:19 PM
To: [email protected]
Subject: Re: [TekScopes2] DPO70804? Thanks. The backlight consists of two very small diameter glass tubes about 10 inches long and somewhere around 1/16 inch in diameter. There are two pink wires and one yellow wire coming out of that assembly and going to a plug on a board that appears to be a high-voltage power supply. The power supply board is even labeled "high voltage." I don't think that is an LED backlight. The pc board patterns going from a module on the power supply board are covered with epoxy up to the connector. I cannot figure out a way to measure the voltages out of the connector to the pink and yellow wires without cutting the wires. ? That probably uses LED backlighting, and that may have a separate power connector. So look for that¡ I doubt it¡¯s got the old CCFL backlight, but that would certainly be a separate connector as the voltage is too high to include with signals. Good luck and keep us posted. dan ? ? I have a DPO70804 scope. The display is dark. I have determined that the fluorescent backlight tubes are not lit. I connected an XGA monitor to the XGA socket on the rear, and the XGA monitor displays the scope display and all functions are working correctly. I have been trying to determine if the display tubes or the voltage supply for those tubes is bad, or if the problem is elsewhere. The service manual I have for the unit contains no schematics nor any info on a way to test the fluorescent display circuit. The power supply board has a 20-pin plug with voltages on the pins. All the voltages are correct as per a drawing in the manual, except for the -5 volt pin (pin 18). That measures 0 volts. But on the drawing, there is an asterisk next to the -5 volt pin, with no explanation I can find anywhere of what the asterisk means. The PS-ON pin measures 0 volts and the PW-OK pin measures +5 volts. Can anybody give me any guidance or suggestions?
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Thanks. The backlight consists of two very small diameter glass tubes about 10 inches long and somewhere around 1/16 inch in diameter. There are two pink wires and one yellow wire coming out of that assembly and going to a plug on a board that appears to be a high-voltage power supply. The power supply board is even labeled "high voltage." I don't think that is an LED backlight. The pc board patterns going from a module on the power supply board are covered with epoxy up to the connector. I cannot figure out a way to measure the voltages out of the connector to the pink and yellow wires without cutting the wires.
Zack
That probably uses LED backlighting, and that may have a separate power connector. So look for that¡ I doubt it¡¯s got the old CCFL backlight, but that would certainly be a separate connector as the voltage is too high to include with signals. Good luck and keep us posted. dan ? ? I have a DPO70804 scope. The display is dark. I have determined that the fluorescent backlight tubes are not lit. I connected an XGA monitor to the XGA socket on the rear, and the XGA monitor displays the scope display and all functions are working correctly. I have been trying to determine if the display tubes or the voltage supply for those tubes is bad, or if the problem is elsewhere. The service manual I have for the unit contains no schematics nor any info on a way to test the fluorescent display circuit. The power supply board has a 20-pin plug with voltages on the pins. All the voltages are correct as per a drawing in the manual, except for the -5 volt pin (pin 18). That measures 0 volts. But on the drawing, there is an asterisk next to the -5 volt pin, with no explanation I can find anywhere of what the asterisk means. The PS-ON pin measures 0 volts and the PW-OK pin measures +5 volts. Can anybody give me any guidance or suggestions?
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That probably uses LED backlighting, and that may have a separate power connector. So look for that¡ I doubt it¡¯s got the old CCFL backlight, but that would certainly be a separate connector as the voltage is too high to include with signals. Good luck and keep us posted. dan ?
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From: [email protected] <[email protected]> On Behalf Of Zack Widup via groups.io
Sent: Tuesday, April 16, 2024 1:42 PM
To: [email protected]
Subject: [TekScopes2] DPO70804? I have a DPO70804 scope. The display is dark. I have determined that the fluorescent backlight tubes are not lit. I connected an XGA monitor to the XGA socket on the rear, and the XGA monitor displays the scope display and all functions are working correctly. I have been trying to determine if the display tubes or the voltage supply for those tubes is bad, or if the problem is elsewhere. The service manual I have for the unit contains no schematics nor any info on a way to test the fluorescent display circuit. The power supply board has a 20-pin plug with voltages on the pins. All the voltages are correct as per a drawing in the manual, except for the -5 volt pin (pin 18). That measures 0 volts. But on the drawing, there is an asterisk next to the -5 volt pin, with no explanation I can find anywhere of what the asterisk means. The PS-ON pin measures 0 volts and the PW-OK pin measures +5 volts. Can anybody give me any guidance or suggestions?
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I have a DPO70804 scope. The display is dark. I have determined that the fluorescent backlight tubes are not lit. I connected an XGA monitor to the XGA socket on the rear, and the XGA monitor displays the scope display and all functions are working correctly.
I have been trying to determine if the display tubes or the voltage supply for those tubes is bad, or if the problem is elsewhere. The service manual I have for the unit contains no schematics nor any info on a way to test the fluorescent display circuit.
The power supply board has a 20-pin plug with voltages on the pins. All the voltages are correct as per a drawing in the manual, except for the -5 volt pin (pin 18). That measures 0 volts. But on the drawing, there is an asterisk next to the -5 volt pin, with no explanation I can find anywhere of what the asterisk means. The PS-ON pin measures 0 volts and the PW-OK pin measures +5 volts.
Can anybody give me any guidance or suggestions?
Zack
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Re: Help! I bricked a perfectly functioning 2467B!
High Don,
Try a search with "Motorola S Records" and the other popular record and file format at the time was "Intel HEX" formatted data records.
You should get many hits.
Richard Hall
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Re: 2465A/B Calibration Restoration for A or early B...
Hi Chris, And if that all wasn't enough, notice that they are using different names for the page select and rom select between the "A" scopes, the early "B" scopes (Don's and mine), and the late NVRAM "B" scopes. The "A" scopes call it PAGE SELECT and ROM SELECT The old "B" scopes call it PB0, PB1, and PB2 The new "B" scopes call it PGSEL 0, and PGSEL 1. I think someone noticed the mistake in the "A" scopes, where ROM SELECT was really /ROM SELECT or RAM SELECT. I think they were moving away from the 27512 EPROMS to the 27011 banked EPROMS, and maybe made it in the early "B", but definitely made it for the late "B" NVRAM scopes... only they needed an additional 64K... I have an assembler, so I am going to attempt to clear up some of the mud by finding out which EPROM is the boot EPROM, and which half is the boot half. -Chuck On Sun, 14 Apr 2024 16:35:25 -0500 "Chris Elmquist" <chrise@...> wrote: On Sunday (04/14/2024 at 10:42AM -0400), Chuck Harris wrote:
Hi Chris,
The A15 pin for the EPROMS is not tied high, but rather is tied
directly to the output of the PAGE SELECT bit of a 74LS174 latch. Yes! I see that now and miss the connection off-sheet that I was
looking at. It does meet up with P503, which jumpers to 5V, via 10K,
and that appears to just be a pull-up on that net.
The PAGE SELECT bit of the register determines whether the 6808
sees the top half, or the bottom half of each 64K EPROM.
There is a further subdivision of memory that occurs, when the
A15 pin of the 6808 is high, the U2260 EPROM is selected. When
the A15 pin of the 6808 is low, the U2160 EPROM is selected.
When the scope is turned on, the reset line is enabled, which
causes the 74LS174 latch to set all of its outputs low, which
will cause the PAGE SELECT and the ROM SELECT pins to both be
low. This is the position they will be in when the RESET line
is released, and the CPU starts execution.
PAGE SELECT being low, should cause the A15 pin of the EPROMS to
be low (they are directly tied together), and the lower half of
each EPROM should be selected.
ROM being low, should cause the full address range of the ROM to
be selected, which means the ROMS will overlay the 8000 - 9FFF
RAM addresses. The 0 to 7FF RAM will be available, however.
When the RESET clears, and the CPU starts execution, it will see
the middle of the EPROM as being the location for the jump vector.
It should also pick the U2260 EPROM. So, the jump vector will be
at the top of the bottom half of the U2260 EPROM.
So, we want our reset vector to end up at $3FFE in the prom-- that's
the very end of the first 16K ??
The NMI interrupt is only generated when the power supply generates
the POWER DOWN signal. That should not happen until the scope is
turned off, or the plug is pulled. I would populate the NMI jump
vector with a jump to a halt instruction. Yes. I have all interrupt vectors SWI, IRQ and NMI pointing at a hang
loop.
Reset is the only one that will point to useful code, the very
beginning of our copy loop.
I don't see any reason to populate the 4 PAGES of EPROM with jump
vectors (including NMI) because it is entirely under our control,
and there is no reason for us to want to change them for the
purposes of this hack. I only suggested copies if we were going to be unsure about which half
of the prom would actually be selected but I think we are past that
now so will just put one copy at the end of the first 16K in the
PROM.
We should set ROM SELECT to HIGH, but leave PAGE SELECT LOW, first
thing so we uncover the RAM addresses from 8000 to 9FFF which will
uncover our calibration constants. Yes- and so that is the last bit for me to code for-- setting the
ROM SELECT to HIGH. I will review your older messages as I believe
you identified the address where that I/O resides. Just need to
figure out which bit to set.
When we have copied all of the calibration constants from the EPROM
to the calibration RAM, we should put the processor into a halt
state, and wait for the user to turn off the power, which will
generate a NMI. The NMI jump vector should have already been set
to point to a halt instruction. Yes. It's going to just hang in a branch-to-self loop.
Note, don't use the undocument "Halt and Catch Fire" instruction.
we don't want our address bus to be counting wildly while the power
is going down. We want the processor to be quiet as possible. No, not that one. Even though there was a TV series named after it?
LOL.
I find that the naming of the PAGE SELECT and ROM SELECT is
problematic. Their names imply that a high on PAGE SELECT picks the
high page, and a high on ROM SELECT picks the ROM over the RAM.
And yet, the manual states that a high on either PAGE SELECT, or
ROM SELECT will enable the RAM full address mode.
Something is wrong, I think.
The schematics show that PAGE SELECT goes directly to the A15
pins of the EPROMS U2260 and U2160. This means that PAGE SELECT
high picks the top half of the EPROM, and low picks the bottom
half. Yes- This was the net I followed but missed the connection to the
other sheet where the '174 register is.
The schematics show that ROM SELECT goes into the PAL U2250.
We don't know what goes on in there, but I suspect that there is
an inversion that turns ROM SELECT into /ROM SELECT, which could
also be called RAM SELECT. Or, there is something wrong in the
text of the circuit description that tells how to unshade the
RAM (or in my english comprehension...) Right-- goes in on pin 5 of that PAL so they could do any number of
fun things with the other addressing as a function of that input.
We are going to need to burn a test ROM that give us
something we can probe to verify what is really happening here.
We need to know for sure how to uncover the RAM so that we can
write it. At the very least, we need to try writing RAM one way,
and then the other, and picking the right way for our project.
Questions or Comments? Since both of you guys can burn proms and have the same scope, I am
very hopeful we can get there pretty quickly with just a few cut and
tries.
I will send a first attempt that has just bogus cal values in it--
maybe alternating AA55, 55AA pattern or something, and since we know
you can do the EXER02 thing even with junk cal constants, we should
be able to display this test pattern once we are successful.
Watch for some code soon...
Chris
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