Author Topic: Conversion of 500MHz TDS744A to 1GHz TDS784A  (Read 77355 times)

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Offline Jay_Diddy_BTopic starter

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Conversion of 500MHz TDS744A to 1GHz TDS784A
« on: December 15, 2014, 02:26:14 am »
Hi Group,

In this thread: https://www.eevblog.com/forum/testgear/enabling-option-1m-extended-acquisition-memory-tektronix-tds754a/msg565086/#msg565086

I documented the process for enabling the extended acquisition memory option on TDS7xx scopes. In this thread I am going to show how I successfully converted a 500 MHz TDS744A to the 1GHz TDS784A.

Tools and Equipment needed for this conversion

You need a PC fitted with a GPIB board to run the Tektronix Field Adjustment software. This is described here:

https://www.eevblog.com/forum/testgear/tektronix-tds700a-field-adjust-software-help-needed/msg563939/#msg563939

You need an accurate voltage source. Tektronix use a Data Precision (Analogic) 8200. You need +/- 9.5V, +/-0.95V and +/- 0.095V.
You need a signal generator to 1.005 GHz. Tektronix uses the SG504 with the levelling head. I substituted an Agilent E4425B

Base line measurements

I used my Transmission line avalanche pulse generator to measure the risetime of the unmodified scope:



The pulse generator is documented here:
https://www.eevblog.com/forum/projects/transmission-line-avalanche-pulse-generator/msg185639/#msg185639

The measured risetime was 650ps this is consistent with a 500 MHz scope.

Configuration Resistors

Tinhead documents the configuration resistors on the back of the Acquisition board in this message:

https://www.eevblog.com/forum/testgear/tek-tds-3054b-vs-tds-744a/msg539818/#msg539818

So I removed the Acquisition board. Here is a picture of the board configured for a TDS744A:




And after I removed R1064, the board is configured for a TDS784A:




I put the scope back together and the boot screen changed to this:




Excited by this I measured the risetime again, there was no change:



 Input Hybrids

I started researching eBay to see if the TDS784A used different ceramic hybrids in the input attenuator. I found some listings for the H2462G (pulled from a TDS744A) and H2462J (pulled from TDS784C). I was thinking that may the input hybrids were limiting the frequency response. These are the photographs from eBay:





They looked very similar to me. Somehow it didn't make sense to use the same part number with a revision code for different bandwidths


To be continued ...

Regards,

Jay_Diddy_B
« Last Edit: December 15, 2014, 03:48:56 am by Jay_Diddy_B »
 
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Offline Jay_Diddy_BTopic starter

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #1 on: December 15, 2014, 02:26:41 am »
Continuation..

Not really satisfied that the input hybrids were causing the bandwidth limitation I decided to look closer at the Acquisition Board. I found this picture of a TDS784A Acquisition Board on eBay:



If you look really closely you will see that C1266, C1267, C1268 and C1269 are not populated.

I looked at the schematics in the TDS520B Component Level Service manual to see what these capacitors are used for:





In the second schematic these capacitors are connect across the differential signal leads.

I suspected that these capacitor are there to reduce the bandwidth. I had a look at the Acquisition Board in my TDS744A and they were fitted:





So I carefully removed these capacitors and saved them so I could put them back.

After removing the capacitors you have to run the Signal Path Compensation (SPC).

I checked the risetime again and was significantly faster.

To be continued...

Regards,

Jay_Diddy_B





« Last Edit: December 15, 2014, 03:18:04 am by Jay_Diddy_B »
 

Offline Jay_Diddy_BTopic starter

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #2 on: December 15, 2014, 02:27:05 am »
Continuation ...

Having modified the hardware I used the Tektronix Field Adjustment software to calibrate the scope. The software calls for the use of a SG504 levelled signal generator. I don't have one of these. I used an Agilent E4425B RF Generator and very high quality cable. I found I had to increase the generator output by 5% when the software called for frequencies higher than 500 MHz to compensate for losses in the cable.

After a couple of false starts I was able to calibrate the scope.

Risetime after Modification and Calibration

Here is a picture of the risetime:



The risetime is 360ps, this is consistent with a 1 GHz scope.

Sine wave measurements

Here are some sinewave measurements confirming the increased bandwidth:
 
I started with a 6 MHz signal and adjusted the output of the signal generator for a reading of 100mV RMS on the scope.




I then increased the frequency to 100 MHz and the scope read 100mV



At 500 Mhz still reading 100mV



At 760 MHz the reading dropped to 86mV (-1.3 dB)



At 1 GHz the reading dropped further to 76.6 mV (-2.3dB)




It looks like a successful conversion  :D :D :D

Enjoy !!!

Jay_Diddy_B


« Last Edit: December 15, 2014, 03:45:18 am by Jay_Diddy_B »
 

Offline dxl

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #3 on: December 15, 2014, 08:39:02 pm »
Hi,

i can confirm the modification. I have a TDS754D, which i upgraded to TDS784D by changing the ID resistors. However, the calibration failed, because freqency response was out of spec (1 GHz was low by ~-4 to -5dB). After removing the capacitors, the calibration runs now flawlessly, and the Field Adjustment software
says it passed calibration.

:D

Regards
« Last Edit: December 15, 2014, 08:45:15 pm by dxl »
 

Offline nctnico

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #4 on: December 15, 2014, 08:57:56 pm »
Great hack! I feel so stupid selling my TDS744A earlier this year  |O  |O
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline free_electron

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #5 on: December 15, 2014, 09:10:48 pm »
 :clap:

next modification : a self destruct button. counts down from 10 to 0 then sets the tekronix logo on fire.
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Offline Jay_Diddy_BTopic starter

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #6 on: December 15, 2014, 10:08:49 pm »
:clap:

next modification : a self destruct button. counts down from 10 to 0 then sets the tekronix logo on fire.

There is no need for a self-destruct button, Danaher Corporation is managing the destruction of Tektronix  :-BROKE

(There is already a emoticon for this !!!)

Regards,

Jay_Diddy_B
 

Offline Carrington

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #7 on: December 15, 2014, 10:27:14 pm »
I did something similar with my MSO6034A, i.e I remove a capacitor located at the differential output, and the overshoot decreased slightly.
But no idea about the frequency response, probably not the most adequate.

To achieve a BW of 500 MHz also is necessary to modify the RC network at the input. And to achieve 1GHz the hybrid and the RC network must be replaced.
My English can be pretty bad, so suggestions are welcome. ;)
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Offline Ivan7enych

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #8 on: December 16, 2014, 08:11:10 am »
So I carefully removed these capacitors and saved them so I could put them back.

After removing the capacitors you have to run the Signal Path Compensation (SPC).

Thank you for this investigation!

I have no old GPIB board now. What do you think, if I simply remove 4 capacitors without running Signal Path Compensation, will it make some problems?
 

Offline dxl

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #9 on: December 16, 2014, 09:06:56 am »
It probably won't make 'problems', but the signal levels shown >500MHz are most likely wrong.
 

Offline nctnico

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #10 on: December 16, 2014, 09:42:46 am »
The sensitivity for low signals isn't great. If you look at the specs of the TDS784A you'll see it struggles to get to 1GHz.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline Jay_Diddy_BTopic starter

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #11 on: December 16, 2014, 01:31:37 pm »
So I carefully removed these capacitors and saved them so I could put them back.

After removing the capacitors you have to run the Signal Path Compensation (SPC).

Thank you for this investigation!

I have no old GPIB board now. What do you think, if I simply remove 4 capacitors without running Signal Path Compensation, will it make some problems?

You don't need any external equipment to run the SPC. It is built into the scope. Go to the Utility menu, select CAL, run the SPC. The SPC takes about 5 minutes.

I initially calibrated channels 1 & 2 using the field adjustment software, which requires the GPIB Card and compared them to channels 3 & 4 which I did not calibrate. There was very little difference with my scope.

The calibration is only as good as the signal generator used for the calibration. The Agilent E4425B that I used is very good.

It takes about 40 minutes per channel to perform the HF CAL.

Regards,

Jay_Diddy_B
 

Offline Ivan7enych

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #12 on: January 14, 2015, 11:20:19 am »
For now I'm quite happy with the modded tds754->784, it allows me to see 1.2GHz output from antenna and to use it as a simple spectrometer, see ouput frequency and power. RF output from selfmade cloverleaf antenna is put directly to 50ohm terminated oscilloscope input.

Model type resistor has been removed, capacitors on every channel removed, field calibration hasn't been done yet.
« Last Edit: January 14, 2015, 11:23:45 am by Ivan7enych »
 

Offline Jay_Diddy_BTopic starter

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #13 on: January 14, 2015, 12:34:36 pm »
Hi Ivan7enych and the group,

The modification seems to work well !!

I am waiting on the delivery of a Fluke 6061A RF generator that I ordered from eBay so that I can automate the adjustment process.

Regards,

Jay_Diddy_B

 

Offline szhebo

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #14 on: June 06, 2015, 11:23:45 am »
Hi,

i can confirm the modification. I have a TDS754D, which i upgraded to TDS784D by changing the ID resistors. However, the calibration failed, because freqency response was out of spec (1 GHz was low by ~-4 to -5dB). After removing the capacitors, the calibration runs now flawlessly, and the Field Adjustment software
says it passed calibration.

:D

Regards

Hi dxl?


I also have a TDS754D, and want to upgrade it to TDS784D, but the schematic is different from the TDS744A, I tried to find TDS784D acquisition board photos on the web, but failed.


Could you please tell me how to change the ID resistors of TDS754D, from R52 to R57, which on should be removed and which one should be added/Keeped?


And for the signal path I found two capacitors across each signal leads, one is C781/C782/C783/C784, another is C740/C741/C742/C743, and the second one with two 3.3K resistors in series across the signal leads. My question is if two capacitors(C781/C782/C783/C784+C740/C741/C742/C743) of each path need to be removed or only the previous one(C781/C782/C783/C784) need to be removed?


Looking forward to your reply!


Many thanks!


Regards,


szebo


 

Offline Jay_Diddy_BTopic starter

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #15 on: July 26, 2015, 02:03:29 am »
Hi,

Somebody asked for the TDS adjustment software.

It is attached to this message.

Regards,

Jay_Diddy_B

 

Offline EB5AGV

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #16 on: July 26, 2015, 05:06:06 pm »
Hi all,

Thanks a lot for this thread!

Last year I bought a TDS 744A as part of a test-equipment lot buying. It came with a couple P6139A probes, the pouch and, free of charge, lots of dirt  ;)

I had not done more than powering it up and some basic checks. It worked, but needed cleaning. My usual digital oscilloscope is a DPO 3032, which is a 300MHz, 2.5Gs/s unit. So, except for the 500MHz bandwidth, the TDS 744A was a lesser unit and I didn't find any use for it at the moment.

But testerday, while looking for other info on a different project (a Tektronix CSA 8000 mainframe I am trying to get back to work), I stumbled upon this thread. Wow!!!. I was amazed to find I had a hidden treasure  :-+, as my 744A came without 1M option... which seemed to be also a configuration hack (and, yes, I have managed to activate it using just Keysight IO libraries and GPIB  :-DD)

So I took it out its casing and carefully cleaned it, including the keypads, as some keys were not working fine. The HORIZONTAL POSITION control also failed, so I took out all the front panel, dismantled and cleaned it. Now the oscilloscope looks like a close to new unit! (I will put some pictures later)

Well, once I performed the resistor mod and the capacitor removal, yes, the unit is shown as a 784A and now it reaches 4 Gs/s. I have run the SPC after a warm up period, and it has also worked fine. But there is a problem when the unit works at 4 Gs/s, which I think it is a matter of calibration. The test is simple: I put a 250MHz signal and activate only Channel 1. What the unit shows is a distorted signal. Then, if I activate Channel 2, so the sampling rate lowers to 2 Gs/s, the signal is an almost perfect sinusoid.

I need to setup a PC with a NI GPIB card to run the calibration software which I hope will solve this problem.

Regards,

JOSE
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Offline Jay_Diddy_BTopic starter

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #17 on: July 26, 2015, 08:51:13 pm »
Hi Jose and the group,

I think that distortion will go away when you perform the calibration. At 4 GS/s all four ADCs are being used and the interleave timing has to be correct to get an undistorted sine wave. At 2GS/s the scope was calibrated when it was TDS 744A.

Regards,

Jay_Diddy_B
 

Online cncjerry

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #18 on: July 27, 2015, 04:42:38 am »
I did the same upgrades to my 744, regularly run high frequencies into it and not only sine waves.  I haven't done the calibration and don't see any distortion like the new poster.
 

Offline EB5AGV

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #19 on: July 27, 2015, 08:25:22 am »
I did the same upgrades to my 744, regularly run high frequencies into it and not only sine waves.  I haven't done the calibration and don't see any distortion like the new poster.

Yes, this is not unusual. Note that the compensation among samplers could be better in your unit without correction. Anyway, I doubt it is perfect, but probably lots less noticeable than on my unit.

All in all, I am happy with the experience. I hope I can fix it by calibration. If not, well, I can always revert the mod. It has been so far an interesting learning experience and a way to get back to life an old and tired unit  ;)

BTW, just adding Option 1M is already worth the effort  :-+

Regards,

JOSE
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Offline tford

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #20 on: January 05, 2016, 01:09:10 am »
After reading the TDS744A to TDS784A conversion thread, I purchased a used TDS7444 in good condition. It appears to fully operational. Gave it a cleaning and removed the 4 capacitors (C1266, 67, 68, 69) and jumper R1064. The results were the addition of option 1G, (1GSPS Ch1, 1 GSPS CH2). The bandwidth did increase to 1 GHZ for all 4 channels, but no TDS784A 4 GSPS conversion. Any ideas of what I can do to complete the conversion? Also, I have FV:v1.1e instead of v1.0.1e. 
Thanks
 

Offline nctnico

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #21 on: January 05, 2016, 01:47:49 am »
Perhaps the jumper is wrong one. Option 1G limits the samplerate to 1Gs/s instead of 2Gs/s (for export purposes) so this is BAD!
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline tford

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #22 on: January 05, 2016, 11:26:50 pm »
I checked my R1064 removal, all was good. I then removed all resistor jumpers, attached small wires to the R1061 through R1064 pcb pads and ran the wires out the board to a dip switch. With R1064 shorted and R1061,62,63 open, my power on self test screen displayed a TDS784 and the sample rate jumped to 4GSPS. Yeah! With all jumpers open, no TDS scope model was displayed on power up. Possibly the firmware version is set up to read the jumpers differently.
 

Offline nctnico

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #23 on: January 06, 2016, 01:13:31 am »
So the setting is the other way around: R1064 must stay!
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline tford

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #24 on: January 19, 2016, 08:06:46 pm »
I would like to capture my TDS744A scope screen display image and store it on my computer for reference. What is the TDS7xx hardware/software setup you all are using to post these perfect scope screen images?
Thanks, Tom
 

Offline Jay_Diddy_BTopic starter

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #25 on: January 19, 2016, 11:32:30 pm »
I would like to capture my TDS744A scope screen display image and store it on my computer for reference. What is the TDS7xx hardware/software setup you all are using to post these perfect scope screen images?
Thanks, Tom

The images were made by printing or plotting to the floppy drive in the scope.

You have to configure the plotting in the 'UTILITY' menu and then plot with the HARDCOPY key.

Regards,

Jay_Diddy_B
 

Offline tford

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #26 on: January 20, 2016, 11:35:13 pm »
Got it. I'll likely have to purchase a USB 3.5" floppy disk drive for my PC, only about $15. I was hoping to use the rear scope centronics or serial connector and go directly into my PC, but those options are limited. 
Thanks,
Tom
 

Offline Jwalling

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #27 on: January 21, 2016, 01:36:03 pm »
Got it. I'll likely have to purchase a USB 3.5" floppy disk drive for my PC, only about $15. I was hoping to use the rear scope centronics or serial connector and go directly into my PC, but those options are limited. 
Thanks,
Tom

You can use the GPIB interface if you use John Miles' excellent 7470 plotter.
http://www.ke5fx.com/gpib/7470.htm

Jay
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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #28 on: March 21, 2016, 03:19:13 pm »
Get the plotting software mentioned earlier from John Miles, www.ke5fx.com.

Also, I am starting to think the distortion we discussed a while back was caused by the poster's scope seeing the 2nd harmonic, or some of it, in 4Gsps mode and not in 2Gsps mode.
 

Offline Jwalling

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #29 on: July 01, 2016, 02:38:23 pm »
Continuation ...

Having modified the hardware I used the Tektronix Field Adjustment software to calibrate the scope. The software calls for the use of a SG504 levelled signal generator. I don't have one of these. I used an Agilent E4425B RF Generator and very high quality cable. I found I had to increase the generator output by 5% when the software called for frequencies higher than 500 MHz to compensate for losses in the cable.

After a couple of false starts I was able to calibrate the scope.

[images snipped]

It looks like a successful conversion  :D :D :D

Enjoy !!!

Jay_Diddy_B

Nice job!  :-+ You inspired me to try this on a TDS754A. However, I hit a roadblock on the HF_CAL. Like you, I don't have a Tek SG504, and instead tried using a R&S SMT 03. The SMT 03 only has output to +13dBm / 1.0V. This is not enough for the calibration to continue (I didn't find this out until almost 2 hours into the cal process.  |O Now all the calibration constants are Initialized.

Do you remember the max amplitude you needed to use on your E4425B during HF_CAL?
Looking at the specs on the E4425B, it too also has a max of 13dBm. Do you have Option UNB high output which gives +17dBm?

Looks like I'll need to score an amplifier - I was looking at HP 8447D amps but they are a bit pricey!
EDIT: not only that, but the output is only +7dBm - never mind...

Anyone have any recommendations for a low cost amp with a minimal frequency range of 6MHz to 1.05GHz?

Thanks!

Jay
« Last Edit: July 01, 2016, 02:48:17 pm by Jwalling »
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Offline nctnico

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #30 on: July 01, 2016, 03:51:58 pm »
How about getting a simple mmic based amplifier?
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline Jay_Diddy_BTopic starter

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #31 on: July 01, 2016, 04:26:37 pm »
Hi,

As well as needing high amplitude, the signal needs to be levelled. That is the amplitude needs to  be constant over the frequency range.

You may trouble if you use a MMIC amplifier.

Regards,

Jay_Diddy_B
 

Offline nctnico

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #32 on: July 01, 2016, 04:33:51 pm »
Hi,

As well as needing high amplitude, the signal needs to be levelled. That is the amplitude needs to  be constant over the frequency range.

You may trouble if you use a MMIC amplifier.
If you use an RF generator you can adjust the amplitude so the output of the MMIC is correct.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #33 on: July 01, 2016, 04:38:50 pm »
Looks like I'll need to score an amplifier - I was looking at HP 8447D amps but they are a bit pricey!
EDIT: not only that, but the output is only +7dBm - never mind...

The 8447E is the power amp version, with +12.5dBm output.

 
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Offline Jwalling

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #34 on: July 01, 2016, 04:41:34 pm »
Looks like I'll need to score an amplifier - I was looking at HP 8447D amps but they are a bit pricey!
EDIT: not only that, but the output is only +7dBm - never mind...

The 8447E is the power amp version, with +12.5dBm output.

And that's not enough either.  :(

Jay
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Offline timb

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #35 on: August 11, 2016, 12:13:43 am »
So, last night I took the plunge and did the conversion on my newly acquired TDS 754C.

Initially, all resistors *except* R1064 were populated:



To convert it to a TDS 784C, I removed R1061-63 and populated R1064:



Then I carefully removed the four capacitors, cleaned the area with foam swabs and isopropyl alcohol and reassembled the scope. She booted right up as a TDS 784C!

I hooked my TG 501 Time Mark Generator up, set it to 1ns markers and turned the scope down to the 200ps setting:



So far so good! Let's see how the signal looks in normal mode:



Now, some of the weirdness may be on the TG 501's end, I'm just not certain. (It came to me in pieces and I was never able to calibrate the 1ns output, because until now I didn't have a scope capable of it).

Anyway, I'm pretty happy with the conversion! I haven't calibrated it yet (because I don't have a signal generator that will go that high), but for now it's alright. At least I can get a good idea of higher frequency stuff now, plus there seems to be no change on the 2GS/s or lower ranges, so I can still rely on them and know they're accurate. (I assume this is because the scope already had the cal data up to 500MHz.)

Now to find a proper signal generator to do the calibration! Maybe I'll get lucky and find a SG 504 on the cheap; people want ridiculous amounts for them on eBay, even without the leveling head (which the unit is useless without).
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Offline rx8pilot

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #36 on: August 11, 2016, 12:56:58 am »
Way to go Tim - I was always too scared to try the conversion since I had no real backup option. Now your 750Mhz active probes are not enough and you will be wanting faster ones. The cycle never ends.  :-DD

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Offline timb

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Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #37 on: August 11, 2016, 01:13:43 am »
Way to go Tim - I was always too scared to try the conversion since I had no real backup option. Now your 750Mhz active probes are not enough and you will be wanting faster ones. The cycle never ends.  :-DD

Thanks! I actually got use my hot tweezers to remove the resistors. I bought them like two years ago and they've just sat in my soldering box... Worked perfectly though, no pulled traces or marks on the board!

I hadn't even thought of my probes... Better update my eBay searches!

Speaking of which, I just scored an SG 504 for $100 (the guy had it listed for $800)! No leveling head, but I did find schematics and a PCB layout for a DIY replacement. (There's even a guy on eBay who builds and calibrates them to 0.1%, which is ten times better than the original Tek head! He wants $120 though, so I'll have a crack at building one myself first.)
« Last Edit: August 11, 2016, 01:16:15 am by timb »
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Offline rx8pilot

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #38 on: August 11, 2016, 01:25:59 am »
I have been hoping to get my hands on one of these fast pulse generators. Designed by esteemed forum member based on the Jim Williams design but with some clever updates.

I would love to get a kit, or gerbers, or a built unit, whatever. Obviously you need a proper signal generator first to calibrate, but it could be used to see how the scope responds to a fast edge. Since it only samples at 2Gs/s - you are right at the Nyquist at 1Ghz where the front end starts to roll off.
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Offline Jay_Diddy_BTopic starter

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #39 on: August 11, 2016, 02:09:39 am »
Hi,

Part of the calibration process is to adjust the timing between the samplers. The samplers are interleaved at the high sampling rates. When you do this the waveforms become a lot smoother. This a picture of mine after the calibration:



The scope use Equivalent Time sampling, indicated by the ET on the screen. Different parts of the waveform are acquired on different acquisitions. This fine for repetitive waveforms, but no use for single shot events.

There are a couple of Avalanche pulse generators on this forum. There is one designed by Free Electron.
This uses the 2N2369 transistor.

That thread can be found here:

https://www.eevblog.com/forum/blog/eevblog-306-jim-williams-pulse-generator/


I designed one that uses a BFR505 transistor which is significantly faster.

The thread starts here: https://www.eevblog.com/forum/projects/transmission-line-avalanche-pulse-generator/



I got to this level of performance:



This is measured with a 20 GHz scope.


This is what the risetime of my 744A looks like after conversion and calibration:






You need a waveform with a flat top to measure the risetime. If you don't you can get very optimistic results.

Good luck !!

Jay_Diddy_B


« Last Edit: August 11, 2016, 02:12:49 am by Jay_Diddy_B »
 

Offline Jay_Diddy_BTopic starter

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #40 on: August 11, 2016, 02:26:52 am »
Hi,

I managed to get the Tektronix field adjustment software to run in an automated manner.

I got some useful tips from this YouTube video:



This guy has some other similar videos, but he stops short of giving all the answers.

The Tektronix software is not all that friendly.

I found that it worked for me with the following equipment:

Hp3478A DMM
Analogic (Data precision) 8200 DC voltage standard
Fluke 6061A

You still have to move the cables around *a lot*

The software checks the high frequency cal for each channel in 20 MHz steps from 500MHz to 1 GHz if I remember correctly.

Some of the adventure is documented in this thread:

https://www.eevblog.com/forum/testgear/tektronix-tds700a-field-adjust-software-help-needed/msg563939/#msg563939


Regards,

Jay_Diddy_B
 

Online cncjerry

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #41 on: August 11, 2016, 03:31:33 am »
I have been hoping to get my hands on one of these fast pulse generators. Designed by esteemed forum member based on the Jim Williams design but with some clever updates.

I would love to get a kit, or gerbers, or a built unit, whatever. Obviously you need a proper signal generator first to calibrate, but it could be used to see how the scope responds to a fast edge. Since it only samples at 2Gs/s - you are right at the Nyquist at 1Ghz where the front end starts to roll off.

After the upgrade the sample time is doubled to 4G.  There was also a way to enable the rest of the memory using software and a switch in the side. 
 

Offline rx8pilot

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #42 on: August 13, 2016, 12:09:07 am »
I had no idea the hardware could do that. Awesome.

Sent from my horrible mobile....

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #43 on: August 13, 2016, 12:59:27 am »
The 784 scope is just a beast.  I have a 3054B as well and though it is loaded with features, when I need to stare at a signal, I use my upgraded 784.  It has a very, very crisp display no matter what the detractors say about the shutter.  The colors are rich, much more so than an LED display. I often wonder why these displays weren't advanced. It's clear to me that the LED display is inferior and is used to cut cost like a front wheel drive car; sold as better but really just a way to cut manufacturing costs.

One thing I have to dig into on mine, is it seems like my scope has a lot of noise on the probe compensation test points.  It could be just the local FM stations leaking through the probe cables.  Do you guys see that as well?  put it in envelope mode and probe the test points.

Thanks
 

Offline timb

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #44 on: August 13, 2016, 01:14:03 am »
The 784 scope is just a beast.  I have a 3054B as well and though it is loaded with features, when I need to stare at a signal, I use my upgraded 784.  It has a very, very crisp display no matter what the detractors say about the shutter.  The colors are rich, much more so than an LED display. I often wonder why these displays weren't advanced. It's clear to me that the LED display is inferior and is used to cut cost like a front wheel drive car; sold as better but really just a way to cut manufacturing costs.

One thing I have to dig into on mine, is it seems like my scope has a lot of noise on the probe compensation test points.  It could be just the local FM stations leaking through the probe cables.  Do you guys see that as well?  put it in envelope mode and probe the test points.

Thanks

The probe calibrator on the TDS 5/7xx series is pretty crappy when compared to some of Tektronix's previous work (like the calibrator on the 2465 series, which automatically changes frequency from 100Hz to 5MHz, depending on what sweep rate you've got set; the output is semi-regulated and has very fast rise and fall times).

On these TDS scopes, the calibration signal is provided by the little MCU on the front panel (it monitors the pots and buttons and talks to the CPU over a serial interface). Basically, it's just programmed to waggle a GPIO at 1kHz, which is then amplified by a transistor.

It's powered by the 5V digital supply, if I remember right, so I'm sure that couples in significant noise. Hitting buttons or twirling knobs will also cause the signal to occasionally drop pulses.

Honestly, an RC oscillator or 555 timer would have been better than using the MCU, but for compensating probes I guess it does the job... (I always use the Fast Rise output of my PG 506 or my 2465B's output for probe compensation anyway, so it doesn't bother me much.)
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Offline Wuerstchenhund

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #45 on: August 13, 2016, 11:03:40 am »
The 784 scope is just a beast.  I have a 3054B as well and though it is loaded with features, when I need to stare at a signal, I use my upgraded 784.  It has a very, very crisp display no matter what the detractors say about the shutter.  The colors are rich, much more so than an LED display. I often wonder why these displays weren't advanced. It's clear to me that the LED display is inferior and is used to cut cost like a front wheel drive car; sold as better but really just a way to cut manufacturing costs.

I'm sorry but that is nonsense.

NuColor had a better contrast ratio (thanks to the b/w CRT and the contrast enhancing filter in front of it) and cleaner reproduction of saturated colors than the average color CRT with mask back then, and that was supported by a UI color scheme that mostly relies on highly saturated colors and the use of high contasts (you'll also see the same saturation if you connect an external display, and the TFT retrofit kits that are available for these scopes give pretty much the same "rich" colors as the old NuColor display).

Back in the early '90s NuColor helped Tek to keep costs low (a mono CRT plus the simple LCD shutter was cheaper than a color CRT plus associated circuitry) while avoiding the convergence/sharpness issues which were common to color CRTs. But NuColor became pretty much obsolete when CCFL backlighted TFT panels became mainstream and costs of these panels came down enough thanks to mass production.

The idea that NuColor is superior to a modern TFT panel with LED backlight is silly, really, especially when considering how bad NuColor was at reproducing non-saturated colors or nuances between colors, something modern TFT panels have little problems with. NuColor is gone because it was a technological dead relying on obsolete technology (CRT).
« Last Edit: August 13, 2016, 11:08:39 am by Wuerstchenhund »
 

Offline timb

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #46 on: August 13, 2016, 12:04:10 pm »
The 784 scope is just a beast.  I have a 3054B as well and though it is loaded with features, when I need to stare at a signal, I use my upgraded 784.  It has a very, very crisp display no matter what the detractors say about the shutter.  The colors are rich, much more so than an LED display. I often wonder why these displays weren't advanced. It's clear to me that the LED display is inferior and is used to cut cost like a front wheel drive car; sold as better but really just a way to cut manufacturing costs.

I'm sorry but that is nonsense.

NuColor had a better contrast ratio (thanks to the b/w CRT and the contrast enhancing filter in front of it) and cleaner reproduction of saturated colors than the average color CRT with mask back then, and that was supported by a UI color scheme that mostly relies on highly saturated colors and the use of high contasts (you'll also see the same saturation if you connect an external display, and the TFT retrofit kits that are available for these scopes give pretty much the same "rich" colors as the old NuColor display).

Back in the early '90s NuColor helped Tek to keep costs low (a mono CRT plus the simple LCD shutter was cheaper than a color CRT plus associated circuitry) while avoiding the convergence/sharpness issues which were common to color CRTs. But NuColor became pretty much obsolete when CCFL backlighted TFT panels became mainstream and costs of these panels came down enough thanks to mass production.

The idea that NuColor is superior to a modern TFT panel with LED backlight is silly, really, especially when considering how bad NuColor was at reproducing non-saturated colors or nuances between colors, something modern TFT panels have little problems with. NuColor is gone because it was a technological dead relying on obsolete technology (CRT).

Well, LCDs didn't become fast enough to replace CRT's (for anything with motion in them) until the early 2000's at the earliest. (And even then, hardcore gamers still used CRTs right up until the mid-2000's because LCDs still had slightly perceptible ghosting.)

Then there's the CCFL issue that wasn't really solved until the late-2000's thanks to white LEDs. There's also the issue of full color depth, which you can't get without an expensive IPS panel.

I also don't think NuColor helped keep costs low... In fact, I'd be surprised if a color CRT wouldn't have been a lot cheaper. Linearity and other issues had been pretty much solved by then, due to rapid advances spurred by the computer industry.

Nobody said a NuColor display is better than a modern LCD. The implication is that, if the technology had kept being developed, it could potentially be better. Perhaps it could have been combined with a mono plasma display or even those ultra low profile CRTs that were developed (but never went into mass production) in the early to mid 2000's.

I've got to say, I absolutely love the display on my 754C as well. It's light years better than any LCD could have possibly been of that vintage. In fact, I even like it better than the LCD on my MSO2024B, which *is* modern! It's fast, absolutely oozes contrast, displays a full gamut of colors... It's gorgeous.

(Just a small correction: NuColor was originally designed for electrostatic deflection CRTs [originally it only provided two colors, plus white] for one of Tek's 5000 series scopes in the early 80's.)
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Offline Wuerstchenhund

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #47 on: August 13, 2016, 01:20:30 pm »
Well, LCDs didn't become fast enough to replace CRT's (for anything with motion in them) until the early 2000's at the earliest. (And even then, hardcore gamers still used CRTs right up until the mid-2000's because LCDs still had slightly perceptible ghosting.)

TFTs exited well before the 2000's (HP put one in their Infiniium 54800 scopes back in 1997, as did other scope manufacturers around the same time), and were more than fast enough for stuff like scopes or even motion scenes.

Gamers often used CRTs even after 2000 because they could be operated at higher refresh rates than 60Hz (a limit of LCDs back then), which was necessary to maintain high frame rates as with VSYNC enabled the frame rate is limited by the screen's refresh rate (and without VSYNC there's lots of ugly tearing). Also, many desktop LCD displays came with slow panels to keep prices down.

Quote
Then there's the CCFL issue that wasn't really solved until the late-2000's thanks to white LEDs.

What 'CCFL issue'?

Quote
There's also the issue of full color depth, which you can't get without an expensive IPS panel.

True, but even a cheap TN exceeds the color reproduction capabilities of the these shutter displays.

Quote
I also don't think NuColor helped keep costs low...

Tek at least thought so, as it was in one of their press releases back then.

Quote
In fact, I'd be surprised if a color CRT wouldn't have been a lot cheaper. Linearity and other issues had been pretty much solved by then, due to rapid advances spurred by the computer industry.

Linearity was always a problem with color CRTs, right 'til the end. Replacement of sea of pots with microprocessor controls and self adjustment capabilities did provide some improvements but the problem never went away. As to price, it's not just the price of the tube itself but also the circuitry. A color CRT display is notably more complex than a monochrome display, and the simple shutter required only very little additional circuitry plus some software changes.

Quote
Nobody said a NuColor display is better than a modern LCD.

I believe this is exactly what cncjerry implied.

Quote
The implication is that, if the technology had kept being developed, it could potentially be better. Perhaps it could have been combined with a mono plasma display or even those ultra low profile CRTs that were developed (but never went into mass production) in the early to mid 2000's.

It is highly unlikely that a technology that relies on a fragile vacuum-ized glas containment and very high voltages could ever have kept up with LCDs which are inherently free of linearity/convergence problems, more robust, have a longer service life, use less power and are cheaper to manufacture. And, like it or not, Plasma is dead for pretty much the same reason.

Quote
I've got to say, I absolutely love the display on my 754C as well. It's light years better than any LCD could have possibly been of that vintage. In fact, I even like it better than the LCD on my MSO2024B, which *is* modern! It's fast, absolutely oozes contrast, displays a full gamut of colors... It's gorgeous.

Not saying the display on the TDS700C isn't good, and I can see why you prefer it to that cheap-ass TN in the MSO2024B (which is pretty poor), although the MOS2k's UI certainly plays its part as well. But in reality there is no "full gamut of colors" (and even if the display was capable of it, which it isn't, you couldn't possibly say because the scope hardware can't do more than 256 colors, and the UI uses a lot less than that), and while it fulfilled its purpose of providing a crisp and clear display for a digital scope, it's definitely no competition for a decent LCD.
« Last Edit: August 13, 2016, 01:24:13 pm by Wuerstchenhund »
 

Offline timb

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #48 on: August 13, 2016, 01:57:07 pm »
Well, LCDs didn't become fast enough to replace CRT's (for anything with motion in them) until the early 2000's at the earliest. (And even then, hardcore gamers still used CRTs right up until the mid-2000's because LCDs still had slightly perceptible ghosting.)

TFTs exited well before the 2000's (HP put one in their Infiniium 54800 scopes back in 1997, as did other scope manufacturers around the same time), and were more than fast enough for stuff like scopes or even motion scenes.

Gamers often used CRTs even after 2000 because they could be operated at higher refresh rates than 60Hz (a limit of LCDs back then), which was necessary to maintain high frame rates as with VSYNC enabled the frame rate is limited by the screen's refresh rate (and without VSYNC there's lots of ugly tearing). Also, many desktop LCD displays came with slow panels to keep prices down.

Quote
Then there's the CCFL issue that wasn't really solved until the late-2000's thanks to white LEDs./
Quote

What 'CCFL issue'?

Quote
There's also the issue of full color depth, which you can't get without an expensive IPS panel.

True, but even a cheap TN vastly exceeds the color reproduction capabilities of NuColor.

Quote
I also don't think NuColor helped keep costs low...

Tek at least thought so, as it was in one of their press releases back then.

Quote
In fact, I'd be surprised if a color CRT wouldn't have been a lot cheaper. Linearity and other issues had been pretty much solved by then, due to rapid advances spurred by the computer industry.

Linearity was always a problem with color CRTs, right 'til the end. Replacement of sea of pots with microprocessor controls and self adjustment capabilities did provide some improvements but the problem never went away. As to price, it's not just the price of the tube itself but also the circuitry. A color CRT display is notably more complex than a monochrome display, and the simple shutter required only very little additional circuitry plus some software changes.

Quote
Nobody said a NuColor display is better than a modern LCD.

I believe this is exactly what cncjerry implied.

Quote
The implication is that, if the technology had kept being developed, it could potentially be better. Perhaps it could have been combined with a mono plasma display or even those ultra low profile CRTs that were developed (but never went into mass production) in the early to mid 2000's.

It is highly unlikely that a technology that relies on a vacuum-ized glas containment and very high voltages could ever have kept up with LCDs which are inherently free of linearity/convergence problems, more robust, have a longer service life, use less power and are cheaper to manufacture. And, like it or not, Plasma is dead for pretty much the same reason.

Quote
I've got to say, I absolutely love the display on my 754C as well. It's light years better than any LCD could have possibly been of that vintage. In fact, I even like it better than the LCD on my MSO2024B, which *is* modern! It's fast, absolutely oozes contrast, displays a full gamut of colors... It's gorgeous.

Not saying the display on the TDS700C isn't good, and I can see why you prefer it to that cheap-ass TN in the MSO2024B (which is pretty poor).  But in reality there is no "full gamut of colors" (and even if the display was capable of it, which it isn't, you couldn't possibly say because the scope hardware can't do more than 256 colors, and the UI uses a lot less than that), and while it fulfilled its purpose of providing a crisp and clear display for a digital scope, it's definitely no competition for a decent LCD.

I know LCDs existed before 2000.... My point was that they were extraordinarily laggy. Yes, even the "Active Matrix" TFT ones.

Refresh rate had nothing to do with why gamers used CRTs. Nobody kept VSYNC on either because, like you said, it limited frame rate. The reason CRTs were used by hardcore gamers has absolutely everything to do with the fact there was no ghosting in the image. No lag. In 2000 even the best LCDs you could get still had lag in the >100ms. I know, because I had a state of the art $1500 Sony LCD, but I still used a Trinitron CRT for gaming. (I was in the #2 ranked East Coast Quake III clan.)

The problem with CCFLs is they have a very finite life, while for the most part CRTs don't. (Though, to be fair, I hear some of the NuColor shutters also have a finite life due to bonding issues.)

Just because LCDs are a cheaper technology doesn't make them better. I personally think plasma TVs have much better pictures compared to LCD sets. Unfortunately it's an expensive technology that has heat and burnin issues, that's why it's basically dead.

The NuColor display on the TDS series is capable of reproducing all 256 colors of the VGA palette pretty clearly, so I don't know why you're saying it's not capable of it?

I'd like to see that press release from Tek talking about NuColor being cheaper than a color CRT. For some reason I just can't imagine it being cheaper. Hell, HP had been using color CRTs since the 80's on their logic analyzers. LeCroy had some of those big ass 1GHz scopes with color CRTs, mid to late 90's vintage, right? (The ones with the thermal printers; they replaced the models with Amber CRTs.)

Keep in mind that NuColor wasn't originally designed for use on a raster scan display. It was designed to produce a color electrostatic CRT for analog oscilloscopes. (It also commanded a $1500 premium compared to the B&W only model when it was originally released in 1984!)

For use on a scope, faced with the choice between:

A) NuColor Display from 1995
B) Color CRT from 1995
C) Color LCD from 1995

I'll take A every single time, with B coming in second. In fact I'd take a monochrome CRT before I took option C!

I guess my point is, up until the early 2000's, LCDs were not a realistic option for oscilloscopes (yes, a few had them, but they were either absolute budget models with blurry monochrome LCDs or very high end models with clear yet expensive color displays).
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Offline andy2000

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #49 on: August 13, 2016, 03:12:57 pm »
JVC made a small professional video monitor that used the same technology.  It has no trouble reproducing the full color depth of a TV image.  The only issue it has is the slight color fringing on fast motion. 

http://pro.jvc.com/pro/pr/nab/tml450tu.htm
 

Offline Wuerstchenhund

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #50 on: August 13, 2016, 03:22:27 pm »
The problem with CCFLs is they have a very finite life, while for the most part CRTs don't.

Of course CRTs have a finite life. The average 'half-time' of a CRT tube is around 20k hrs, after which the brightness will have fallen by 50%, and after which it will decline further. In addition, the lifetime is limited by some of its parts, i.e. the heater filament.

CCFL tubes have a life span of somewhere in the range of 10k to 100k hrs.

Quote
(Though, to be fair, I hear some of the NuColor shutters also have a finite life due to bonding issues.)

This is just another issue on top.

Quote
Just because LCDs are a cheaper technology doesn't make them better.

LCD is not better because it's cheaper, it is better because it is the better performing technology.

The fact that it's cheaper (these days, it wasn't back in the mid-90s) is just the bonus.

Quote
I personally think plasma TVs have much better pictures compared to LCD sets. Unfortunately it's an expensive technology that has heat and burnin issues, that's why it's basically dead.

Yes, and also because modern LCDs are much better than they were ten years ago.

Plasma's strenght has been its superior reproduction of black, but that was back then. The price one paid for plasma, as you said, was fragility, heat/power consumption, and a very limited service life.

Quote
The NuColor display on the TDS series is capable of reproducing all 256 colors of the VGA palette pretty clearly, so I don't know why you're saying it's not capable of it?

What makes you think the TDS uses all 256 colors? From what I remember (OK, it's been a while) the UI itself uses just 16 out of 256 colors, and color grading I believe was limited to 16 or 32 colors.

Quote
I'd like to see that press release from Tek talking about NuColor being cheaper than a color CRT. For some reason I just can't imagine it being cheaper.

I don't have the original release but I managed to find this:

http://www.electronicproducts.com/Test_and_Measurement/Oscilloscope_makers_ride_the_color_bandwagon.aspx

...The substantially lower cost of the NuColor display when compared with traditional shadow-mask displays played a big part in Tektronix being able to price the scopes so aggressively. Shadow-mask displays used in color DSOs (including their additional memory, power, and circuit needs) from Tektronix, Hewlett-Packard, and LeCroy in the past have  added about $2,000 to $3,000 to the cost of a color scope. The estimated added costs with the NuColor display is only about $500 or so, according to Martinez.

It shows that at least Tek believed it's cheaper to do NuColor than use a color CRT.

Quote
Hell, HP had been using color CRTs since the 80's on their logic analyzers. LeCroy had some of those big ass 1GHz scopes with color CRTs, mid to late 90's vintage, right? (The ones with the thermal printers; they replaced the models with Amber CRTs.)

Yes, but that doesn't show that color CRTs were cheaper. It shows that, at that time, LeCroy and HP thought that this is the appropriate technology for their digital scopes (and other kit in case of HP). Don't forget that in the digital scope market Tek suddenly found itself surrounded by much stronger competition than in the analog scope market (where Tektronix was pretty much the technology leader).

Quote
Keep in mind that NuColor wasn't originally designed for use on a raster scan display. It was designed to produce a color electrostatic CRT for analog oscilloscopes. (It also commanded a $1500 premium compared to the B&W only model when it was originally released in 1984!)

I can't remember about NuColor for analog scopes. What scope models was it used in, and what for?

Quote
For use on a scope, faced with the choice between:

A) NuColor Display from 1995
B) Color CRT from 1995
C) Color LCD from 1995

I'll take A every single time, with B coming in second. In fact I'd take a monochrome CRT before I took option C!

In 1995 there was no big brand scope with color LCD I remember of. Which means for a 1995 scope I'd probably vote B over A, mainly because I would get a larger screen (the scopes with color CRT like the HP 54700 Series had a larger screens than the TDS series). NuColor would have given me more contrast but for a scope display that is pretty irrelevant, although NuColor would also give less flickering.

Going forward to say 1998, I'd go for C every time. Even back then the readability and sharpness of a LCD like the ones used in the HP 545xxC, 546xxC or the LeCroy WR LT is *a lot* better than even a mono CRT or NuColor could ever provide. Colors might not be so overly saturated as on NuColor (but then, color saturation is was still great at least when the CCFL tube was new, it's only after many hours when the lamp has faded and shifted its color temperature that colors start looking washed out), but frankly for a scope I couldn't care less. As long as the display is clear, crisp and easily readable then it's fine.

Quote
I guess my point is, up until the early 2000's, LCDs were not a realistic option for oscilloscopes (yes, a few had them, but they were either absolute budget models with blurry monochrome LCDs or very high end models with clear yet expensive color displays).

Yes, but then the TDS700 wasn't exactly a bargain bin scope, too. Price-wise it very much did compete with the HP 545xx/546xx and 547xx, or the LeCroy LC 600 and WR LTs. In fact, some of the TFT equipped scopes were notabily cheaper than the TDS700 with NuColor. It may have saved Tek some money, but they certainly didn't pass that on to the customer.
« Last Edit: August 13, 2016, 03:25:39 pm by Wuerstchenhund »
 

Offline dxl

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #51 on: August 13, 2016, 08:14:11 pm »
My TDS754 has a TFT, but only because i had to replace the NuColor Display. The Picture was almost invisible after the tube had being overdriven for 15 Years or so. That's one of the downsides on NuColor: The Shutter display 'eats' a certain amount of light, so Tek decided to crank up the brightness of the Tube which decreases it's life span. Another thing i never liked on the TDS700 series is the glossy shutter. Put the TDS700 in a Room where there's a window on the other side of the room. You have a reason to be happy every day when you have the Sun as Scope background ;)

I don't have much devices from the 90s with color display. But i can say for sure that even the HP70004A display from my Spectrum Analyzer doesn't look bad compared to NuColor. But that display has a Sony Trinitron tube, which was probably way more expensive then a normal Color tube.
 

Offline timb

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #52 on: August 13, 2016, 10:16:21 pm »

I don't have the original release but I managed to find this:

http://www.electronicproducts.com/Test_and_Measurement/Oscilloscope_makers_ride_the_color_bandwagon.aspx

...The substantially lower cost of the NuColor display when compared with traditional shadow-mask displays played a big part in Tektronix being able to price the scopes so aggressively. Shadow-mask displays used in color DSOs (including their additional memory, power, and circuit needs) from Tektronix, Hewlett-Packard, and LeCroy in the past have  added about $2,000 to $3,000 to the cost of a color scope. The estimated added costs with the NuColor display is only about $500 or so, according to Martinez.

It shows that at least Tek believed it's cheaper to do NuColor than use a color CRT.

Quote
Keep in mind that NuColor wasn't originally designed for use on a raster scan display. It was designed to produce a color electrostatic CRT for analog oscilloscopes. (It also commanded a $1500 premium compared to the B&W only model when it was originally released in 1984!)

I can't remember about NuColor for analog scopes. What scope models was it used in, and what for?

The 5116 was the first use of Tek's NuColor technology.

The purpose was to allow different channels to be displayed in different colors. (And for the readout to be color coded as well.)

As for that article you linked, I imagine a lot of that cost they estimate was in the memory itself (which would have been hundreds of dollars per MB in the early to mid 90's), but I don't see why a color CRT would require any more memory than a NuColor display? The power requirements should be similar as well. It would need additional circuitry, but so does the NuColor shutter!

After thinking about it, I guess a small color CRT could have been expensive to produce. Most color TVs started out at 13" and color monitors at 12" so going below that would have increased cost, especially since they didn't have the economy of scale to bring the cost down. By that time Tek would have been making the NuColor shutter for over 10 years, so $500 seems like a reasonable figure.

I just think it was an interesting technology.

Re: TDS color depth... I don't think the TDS displays more than 20 different colors on the screen at any one time; however each color can be selected from any in the VGA palette. You can go into the display menu and scroll through the color list to see for yourself. This isn't a limit of the NuColor hardware, there's just no need to display more than that on this particular scope.

The proof that the hardware is capable of a full color gamut is evident when you look at other products using the technology: Tek made a NuColor computer monitor; JVC made portable color video monitors using the NuColor system, which is capable of displaying any color a normal color CRT TV can.

I do agree the technology is a dead end now and LCDs are clearly better, but like I said earlier, it's fun to speculate what if. I think, as another poster mentioned, the big disadvantage to them is how much light the shutters eat up, requiring you to overdrive the CRT. It's a shame as with 10 more years of development, I think they could have improved on that a lot. Ah well.

Oh, one more thing. Even a modern LCD still struggles to get the black levels of a 10 year old plasma. I also imagine they could have corrected a lot of the deficits, had it continued to be developed like LCDs have. No display technology that needs a backlight will ever be as good as one that produces its own light. Period. That's why I'm keeping my fingers cross and waiting for OLED sets to be perfected before I replace my plasma.

Edit: I almost wonder if the reason I like the NuColor display so much is because of the high refresh rate, which eliminates the 60Hz flicker found on most other raster scan style CRTs of the era. (I had to run my gaming monitor at 85Hz, minimum.)
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Offline siggi

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #53 on: August 13, 2016, 10:46:16 pm »
The 5116 was the first use of Tek's NuColor technology.

Wow, that was a pretty fun read. Toward the end it says "As time goes on then, it is reasonable to assume that the color shutter will be used in a wide variety of products and applications.". Even as the cover photo in the article demonstrates how the trace intensity is skewered by the LCD shutter :).
 

Offline Jwalling

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #54 on: August 13, 2016, 11:12:47 pm »
The 5116 was the first use of Tek's NuColor technology.

Wow, that was a pretty fun read. Toward the end it says "As time goes on then, it is reasonable to assume that the color shutter will be used in a wide variety of products and applications.". Even as the cover photo in the article demonstrates how the trace intensity is skewered by the LCD shutter :).

+1
I had no idea that this technology was around in 1984. I have fond memories (no pun intended) of both Radio Electronics and Popular Electronics. (Still have a bunch of the old magazines) I especially remember the Cosmac Elf 1802 project - my first (big) project I ever did; don't remember what happened to it, but wish I kept it...
I always loved the back pages with all the surplus sellers such as PolyPaks, etc.

EDIT: Link  https://en.wikipedia.org/wiki/COSMAC_ELF
Mine didn't look that nice, though  :)
Jay
« Last Edit: August 13, 2016, 11:15:30 pm by Jwalling »
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Offline nctnico

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #55 on: August 13, 2016, 11:26:24 pm »

I don't have the original release but I managed to find this:

http://www.electronicproducts.com/Test_and_Measurement/Oscilloscope_makers_ride_the_color_bandwagon.aspx

...The substantially lower cost of the NuColor display when compared with traditional shadow-mask displays played a big part in Tektronix being able to price the scopes so aggressively. Shadow-mask displays used in color DSOs (including their additional memory, power, and circuit needs) from Tektronix, Hewlett-Packard, and LeCroy in the past have  added about $2,000 to $3,000 to the cost of a color scope. The estimated added costs with the NuColor display is only about $500 or so, according to Martinez.

It shows that at least Tek believed it's cheaper to do NuColor than use a color CRT.

Quote
Keep in mind that NuColor wasn't originally designed for use on a raster scan display. It was designed to produce a color electrostatic CRT for analog oscilloscopes. (It also commanded a $1500 premium compared to the B&W only model when it was originally released in 1984!)

I can't remember about NuColor for analog scopes. What scope models was it used in, and what for?

The 5116 was the first use of Tek's NuColor technology.

The purpose was to allow different channels to be displayed in different colors. (And for the readout to be color coded as well.)

As for that article you linked, I imagine a lot of that cost they estimate was in the memory itself (which would have been hundreds of dollars per MB in the early to mid 90's), but I don't see why a color CRT would require any more memory than a NuColor display? The power requirements should be similar as well. It would need additional circuitry, but so does the NuColor shutter!
The NuColor display in the Tektronix scopes actually needs more memory. What the display system does is triple the display data coming from the acquisition/CPU overlay (640x480 @60Hz) and split it into 3 color channels and pull that through a RAMDAC which runs at 3 times the clock frequency of regular VGA. Hence the CRT also runs at 180Hz instead of 60. AFAIK the whole NuColor display wasn't to save cost but just to be able to use a rugged monochrome CRT with one big electron cannon instead of 3 smaller ones. After all the TDS500/600/700 series are built like tanks.

With a normal color CRT they could have used the RAMDAC which is already there for the external VGA output.
« Last Edit: August 13, 2016, 11:28:03 pm by nctnico »
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Online David Hess

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #56 on: August 14, 2016, 03:04:55 am »
NuColor displays also allow higher resolution and absence of convergence compared to a color CRT.

Modern LCDs have only just reached the DPI of old vector CRTs and LCDs with that kind of performance are not used in DSOs yet anyway.
 

Offline eKretz

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #57 on: August 16, 2016, 08:40:26 am »
Just finished converting my 754A, FW v4.1e with no issues. Wish I could do the 2M option too, oh well, at least I've got 1M. Got to work on the calibration next.

« Last Edit: August 16, 2016, 09:56:35 am by eKretz »
 

Offline Jwalling

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #58 on: August 16, 2016, 09:57:36 am »
Just finished converting my 754A, FW v4.1e with no issues. Wish I could do the 2M option too, oh well, at least I've got 1M. Got to work on the calibration next.
:-+ On the A scopes, 2M was never an option.

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Offline eKretz

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #59 on: August 16, 2016, 07:40:10 pm »
Yup, I know. Anyone know if the processor and acquisition boards are the only difference between A and D?
 

Offline Jwalling

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #60 on: August 16, 2016, 07:46:33 pm »
Yup, I know. Anyone know if the processor and acquisition boards are the only difference between A and D?

The LV power supplies and HV assemblies are interchangeable. The processor on the D scopes is noticeably faster, and is very noticeable when switching back and forth from DPO/Instavue

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Offline eKretz

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #61 on: August 16, 2016, 08:52:40 pm »
So switching the processor and acquisition boards might net me a 784D then. Hmm. May need to start watching eBay.
 

Offline tford

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #62 on: September 22, 2016, 12:32:57 am »
I may have to replace my upgraded TDS744A CRT with an LCD soon because the shutter module appears to be de-laminating. For anyone that's been down this road before, does the LCD replacement have comparable resolution and ease of viewing? Thanks, Tom.
 

Offline Jay_Diddy_BTopic starter

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #63 on: September 22, 2016, 12:57:29 am »
I may have to replace my upgraded TDS744A CRT with an LCD soon because the shutter module appears to be de-laminating. For anyone that's been down this road before, does the LCD replacement have comparable resolution and ease of viewing? Thanks, Tom.

I suppose it depends on how good an LCD display you get. I converted one of my TDS5xx or TDS7xx to LCD because the CRT was no good. I was never really happy with it. I used to use it as a portable scope, because it made the scope lighter. I prefer the liquid crystal shutter / monochrome display 'NuColor'.


The challenge is you need to find a VGA 640 x 480 LCD the right size. Most of the VGA resolution screens are not that great.

Regards,

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Offline snoopy

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #64 on: September 22, 2016, 08:32:15 am »
For those interested the original brochure for the 700D scopes ;)

https://www.testequity.com/documents/pdf/tds700d.pdf

Quite impressive for the time and still is ;)
 

Offline Wuerstchenhund

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #65 on: September 22, 2016, 10:35:03 am »
Quite impressive for the time and still is ;)

Not really, no. Not in 2001 (the date of that brochure).
« Last Edit: September 22, 2016, 10:40:20 am by Wuerstchenhund »
 

Online KE5FX

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #66 on: September 22, 2016, 10:59:48 am »
Quite impressive for the time and still is ;)

Not really, no. Not in 2001 (the date of that brochure).

Who else was doing 200K waveforms/sec?  That was really the DPO's claim to fame.
 

Offline Wuerstchenhund

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #67 on: September 22, 2016, 11:44:46 am »
Quite impressive for the time and still is ;)

Not really, no. Not in 2001 (the date of that brochure).

Who else was doing 200K waveforms/sec?  That was really the DPO's claim to fame.

HP already had MegaZoom, which managed higher waveform update rates without the issues of DPO (which in those scopes only worked at 1GSa/s or less which also limits the usable BW to less than 450MHz or so, could only use up to 0.5Mpts of memory so sample rates often had to drop considerably which meant further reduction in usable BW, couldn't do measurements, and suffered from loss of signal information through ineffective min/max compression), plus MegaZoom  wasn't a separate mode, it was always on.
« Last Edit: September 22, 2016, 11:47:37 am by Wuerstchenhund »
 

Offline snoopy

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #68 on: September 22, 2016, 12:20:02 pm »
Quite impressive for the time and still is ;)

Not really, no. Not in 2001 (the date of that brochure).

Who else was doing 200K waveforms/sec?  That was really the DPO's claim to fame.

HP already had MegaZoom, which managed higher waveform update rates without the issues of DPO (which in those scopes only worked at 1GSa/s or less which also limits the usable BW to less than 450MHz or so, could only use up to 0.5Mpts of memory so sample rates often had to drop considerably which meant further reduction in usable BW, couldn't do measurements, and suffered from loss of signal information through ineffective min/max compression), plus MegaZoom  wasn't a separate mode, it was always on.

You could turn off DPO and the earlier A and C models never had it anyway. Also the 784A was 1995 vintage and still could do 400K wfrms/s.

http://www.axiomtest.com/documents/models/Tektronix%20TDS784A%20Data%20Sheet.pdf

Not sure what HP had at the time.

What was the model and update rate of that HP scope ?

Anyways the Tek TD694 had 3GHz bandwidth and 10Gs/s on ALL channels although it didn't have InstaVu and Fast Frame (Segmented memory) that the later 700 series had.

http://lsm.epfl.ch/files/content/sites/lsm/files/shared/Equipment/Tektronix_TDS694C.pdf

http://www.testequity.com/documents/pdf/tds684-94c.pdf



« Last Edit: September 22, 2016, 12:28:39 pm by snoopy »
 

Offline Wuerstchenhund

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #69 on: September 22, 2016, 01:19:19 pm »
You could turn off DPO and the earlier A and C models never had it anyway.

You had to turn it off if you wanted to use the full BW and sample rate, and the measurements.

Quote
Also the 784A was 1995 vintage and still could do 400K wfrms/s.

Yes, they had InstaVu, a non-graded persistence display. And similar to DPO, it came with the same disadvantages.

Quote
Not sure what HP had at the time

At that time HP came out with it's first generation of MegaZoom in the 54600 Series of scopes.

Quote
What was the model and update rate of that HP scope ?

The first one were the 54645A and the 54645D (MSO version of the 54645A).

Can't remember what the waveform rate was for the original but I believe it was somewhere in the 250k wfms/s region. The important bit however was that it was not just one large number at a specific setting (as with InstaVu/DPO), it reached high update rates in almost any setting.

Quote
Anyways the Tek TD694 had 3GHz bandwidth and 10Gs/s on ALL channels although it didn't have InstaVu and Fast Frame (Segmented memory) that the later 700 series had.

And it came with a miniscule amount of sample memory (30kpts, 120kpts as "long memory" option) which meant it could only sustain the sample rate at the shortest timbease settings and with longer time bases (i.e. anything over 300ns/s with standard memory or 100ns/div with "long" memory) the sample rate dropped like a stone, limiting the usable BW to a fraction of that 3GHz bandwidth, plus it lacks any advanced measurements or math functions that other scopes had at that time.

The TDS694C is a good example what's wrong with Tek: they build a DSO that was good or even great in one aspect but lacked in pretty much everything else. Which admittedly was better than it is today, where Tek scopes lack pretty much in every aspect and excel in none. Something that is reflected in their continued dwindling market share and plummeting sales.

The key to a good scope isn't in producing some single outstanding feature (that is only good for marketing), it's in a well-balanced approach to the various different properties that define a scope. Tek understood that for analog scopes, but for DSOs they have always seemed to struggle, and still are.

Anyways, I didn't want to derail this thread into a comparison of manufacturers. My point was that the TDS784C wasn't as  impressive for a scope of that class back then in 2001 as you believe it was, and much less so in 2016.
« Last Edit: September 22, 2016, 01:31:00 pm by Wuerstchenhund »
 

Offline nctnico

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #70 on: September 22, 2016, 01:27:25 pm »
IMHO the TDS600 series was specifically made for measurements at the highest samplerate to take single shots of high frequency signals and nothing else. The early ones are totally useless as general purpose scopes due to the lack of peak-detect but even with peak detect their memories are short. The TDS500 and TDS700 series are the models suitable for general purpose use.
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Online David Hess

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #71 on: September 22, 2016, 03:51:22 pm »
IMHO the TDS600 series was specifically made for measurements at the highest samplerate to take single shots of high frequency signals and nothing else. The early ones are totally useless as general purpose scopes due to the lack of peak-detect but even with peak detect their memories are short. The TDS500 and TDS700 series are the models suitable for general purpose use.

This is exactly the case.

The TDS600 series was a continuation of Tektronix's CCD based DSOs optimized for higher samples rates than were available using more conventional designs.  They are more like transient digitizers with oscilloscope ease of use than general purpose oscilloscopes.  If you wanted maximum sample rate on every channel, then this is what you used.  At the time they were produced, they had 10 times (total) or 40 times (per channel) the real time sample rate of the fastest TDS700 series.

Since they used CCDs, features like segmented memory (FastFrame) and DPO operation (InstaView) could not be included.  The early TDS600 models even lacked peak detection which is only surprising because their 2440 ancestors had it; I assume this was a difficult implementation detail that Tektronix had to figure out for inclusion in the TDS600B and later models.

I wonder if they sold a lot of these to nuclear weapon testers like the ancient 519 1 GHz analog oscilloscope.
 

Offline timb

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #72 on: September 22, 2016, 06:48:43 pm »
Speaking of FastFrame... What sort of use case is it for? There's no example in the manual and I never could really think of a situation where it would be useful. (Obviously it is useful, or it wouldn't be a feature!)
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Offline rx8pilot

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #73 on: September 22, 2016, 07:49:09 pm »
(Obviously it is useful, or it wouldn't be a feature!)

I don't know.... a lot of features are designed by the marketing dept and totally useless.
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Offline timb

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #74 on: September 22, 2016, 08:08:44 pm »
(Obviously it is useful, or it wouldn't be a feature!)

I don't know.... a lot of features are designed by the marketing dept and totally useless.

I suppose that's true for a lot of things, though I cant think of many superfluous features on test gear.

Doesn't your new Keysight scope have a voice control feature? I would think something like that was conceived by the Marketing Department. ("Hmmm, Siri is really helping the iPhone sell... We should do that, but on an Oscilloscope!")

That said, if implemented well I can see how it would actually be very useful.

I'm still on the fence about touchscreen based instruments though. It's been tried in many forms over the years, and no one has quite gotten right. (Maybe some of the newer, more expensive scopes that have nice, big capacitive touch screens might work well, I haven't tried them; IR and resistive touch screens of the past just don't cut it.)
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Online David Hess

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #75 on: September 22, 2016, 08:11:31 pm »
Speaking of FastFrame... What sort of use case is it for? There's no example in the manual and I never could really think of a situation where it would be useful. (Obviously it is useful, or it wouldn't be a feature!)

It allows capturing only the relevant parts of a signal around the trigger points and usually produces a much higher waveform acquisition rate without the disadvantages of DPO mode.
 

Offline rx8pilot

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #76 on: September 22, 2016, 08:14:10 pm »
To my surprise - the voice control on the Keysight scope is an awesome feature that I use all the time. When my hands are delicately trying to probe two tiny points - the voice control can save my ass. Start, stop, scaling, and more. Super handy and works with a normal voice and all the fans on my bench going full blast too. I would give up touch screen before voice control.
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Offline snoopy

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #77 on: September 23, 2016, 12:01:31 am »

The first one were the 54645A and the 54645D (MSO version of the 54645A).

Can't remember what the waveform rate was for the original but I believe it was somewhere in the 250k wfms/s region. The important bit however was that it was not just one large number at a specific setting (as with InstaVu/DPO), it reached high update rates in almost any setting.

Hmmm - you need to be more specific regarding wfrms/s because when dave reviewed an older HP 54622 (2000 vintage) with MegaZoom it says something about 25 million vectors per second ??? Go to 8:40 where dave tests the actual update rate - a measily 520 wfrms/s at best  :--

« Last Edit: September 23, 2016, 12:10:54 am by snoopy »
 

Offline MarkL

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #78 on: September 23, 2016, 02:03:53 am »
Hmmm - you need to be more specific regarding wfrms/s because when dave reviewed an older HP 54622 (2000 vintage) with MegaZoom it says something about 25 million vectors per second ??? Go to 8:40 where dave tests the actual update rate - a measily 520 wfrms/s at best  :--
Different meaning of vectors; from the 54645A manual:

Quote
Using Vectors

One of the most fundamental choices you must make about your display is whether to draw vectors (connect the dots)  between the samples, or simply let the samples fill in the waveform. To some degree, this is a matter of personal preference, but it also depends on the waveform.

· You will probably operate the oscilloscope most often with vectors on. Having vectors on slows the display of the oscilloscope, thus works better for slower sweep speeds, peak detect, or average displays, and signals with stable triggers.

· Having vectors off works better for fast sweep speeds, normal displays, or unstable triggers. Complex analog signals like video and eye diagrams show more intensity information with vectors off. Turn vectors off when the maximum display rate is required, or when highly complex or multi-valued waveforms are displayed.
 

Offline Daxxin

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #79 on: December 13, 2017, 11:04:46 am »
Did the modification removing R1064 and 4 caps , but no difference with the banner
 

Offline Jwalling

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #80 on: December 13, 2017, 11:21:58 am »
Not surprising. R1064 should be installed. The other three should be removed.  ;)
Jay

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Offline Vlad_01

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #81 on: March 09, 2018, 04:08:49 am »
TDS744  (without "A")
firmware v.1.0e
Options 13, 1F,1M, 2F

All combinations of resistors are tried, no result.
It looks like I should change the firmware.
On what to change and where to look the instruction?
What is the difference between TDS744 and TDS744A?



There were 3 lintels - R1061, R1062 & R1064.
All 16 combinations are checked, no result.

Detailed photo boards in one file (40 Mb)
http://www103.zippyshare.com/v/c8iduaXp/file.html
« Last Edit: March 09, 2018, 11:36:38 pm by Vlad_01 »
 

Offline oaba

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #82 on: August 30, 2018, 10:29:54 pm »
Vlad_01
I have the same problem. Have you find it out?
What are those configuration 0 resistor are for at tds744?
I removed the capacitors anyway.
« Last Edit: August 30, 2018, 10:31:36 pm by oaba »
 

Offline Jwalling

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #83 on: August 31, 2018, 09:52:26 am »
Vlad_01
I have the same problem. Have you find it out?
What are those configuration 0 resistor are for at tds744?
I removed the capacitors anyway.

The TDS784A did not exist when the non-suffixed TDS744 did. I think removing the caps and installing R1064 only will let the scope sample @ 4GS/s on 1 channel and 1GS/s on four channels simultaneously, but it will still say that it's a TDS744.
Jay

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Offline oaba

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #84 on: August 31, 2018, 11:04:30 pm »
I got it.
Is it possible to modify the firmware? Is that in the NVRAM.
Have you replaced it or saved it?
To prevent future problems.
Thanks.
 

Offline Jwalling

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #85 on: September 01, 2018, 09:25:27 am »
I got it.
Is it possible to modify the firmware? Is that in the NVRAM.
Have you replaced it or saved it?
To prevent future problems.
Thanks.

It's possible, but I wouldn't try it. Google Tekfwtool. You may brick your scope trying...
Jay

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Offline Alfons

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #86 on: November 01, 2019, 02:33:58 pm »
I did it now and it worked immediately. My TDS744a with firmware version 1.1e is now a TDS784a. However, in the first test, signals recorded at 4GS / s showed strong distortions, switched to 2GS / s (two channels turned on), everything was normal. I then ran SPC, which ended with "pass". After that everything was back to normal, the distortions were gone. The bandwidth has doubled and it looks quite accurate even without calibration.

 

Offline strick

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #87 on: November 06, 2019, 01:46:01 am »
Alfons,
would you mind sharing how you updated the firmware on your 744A?  I've updated the 540A series and the 500/700C series, but I haven't seen a tool that worked on the 744A.  All the 744A boards (except one) had the 2F008SA flash and the normal Tektool was built for the 2F016.  Tektool5 is around and works ok for the 500A series but is for the 2F010 and 2F020 chips.

thanks,
Strick
 

Offline radioguy123

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #88 on: November 11, 2019, 06:04:28 pm »
Is it possible to convert a TDS540C into a TDS580C ?
 

Offline Alfons

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #89 on: November 11, 2019, 10:19:33 pm »
Alfons,
would you mind sharing how you updated the firmware on your 744A?  I've updated the 540A series and the 500/700C series, but I haven't seen a tool that worked on the 744A.  All the 744A boards (except one) had the 2F008SA flash and the normal Tektool was built for the 2F016.  Tektool5 is around and works ok for the 500A series but is for the 2F010 and 2F020 chips.

thanks,
Strick

Maybe I did not express myself correctly? I did not change the firmware, but the hardware (remove one resistor and few C's). But that is synonymous here everything in the thread. I have not read anything yet that somebody managed to put up another firmware.

« Last Edit: November 13, 2019, 07:35:11 am by Alfons »
 

Offline radioguy123

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #90 on: November 12, 2019, 02:00:28 pm »
I was just wondering if it is possible to convert a 500mhz TDS540C into a 1Ghz TDS580C ? Just wondering if anyone has researched this ?
Thanks for any info on this.
 

Offline Jay_Diddy_BTopic starter

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #91 on: November 13, 2019, 03:31:44 am »
I was just wondering if it is possible to convert a 500mhz TDS540C into a 1Ghz TDS580C ? Just wondering if anyone has researched this ?
Thanks for any info on this.

Do you have a TDS540C?

If you do, open the case carefully remove the acquisition board and look for configuration resistors. They will probably be on the back of the board.

If you don't try searching the internet for photographs of the A10 acquisition board.


Regards,

Jay_Diddy_B
 

Offline radioguy123

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #92 on: November 13, 2019, 04:21:37 pm »
Yes I do have a TDS540C
So it's the A10 acquisition board that you change ?
I will get the scope open and look at the back of the board.
I have read through this thread and I know you have to remove some capacitors also.
Not to mention the re-cal.
I'll get you the board number in a little bit.
I was just wondering if anyone has tried this.
Thanks for the reply.
The A11 board is: 679-4002-00
The A10 board is: 679-4204-00
« Last Edit: November 13, 2019, 11:22:36 pm by radioguy123 »
 

Offline Alfons

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #93 on: November 13, 2019, 06:33:28 pm »
Please read the thread. You find there, what to look for. On the bottom of the acquisition board are resistors, four pieces. How exactly your equipment must look to change something, I do not know. With my board, it was only necessary to remove one resistor.
 

Offline madao

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #94 on: November 17, 2019, 07:08:33 am »
I think, it is possible.



I have collected list of  A10 & A11 Board part numbers.
TDS540C has same A10 board as by  TDS754C.

TDS540C is just a  TDS754C with monochrome CRT and not 13 & 2F options as standard.

regards
matt

 

Offline Galen

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #95 on: December 17, 2019, 02:07:18 pm »
I have tried to convert my TDS540C to TDS580C, by take out the 4 capacitors and only short the R1064, it shows 4Gs/s, but the banner shows TDS xxx. my firmware is FV:v5.0e. 
Passed SPC.
Maybe it is the firmware version problem?
Delighted when problem fixed
 

Online thm_w

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #96 on: December 17, 2019, 10:45:09 pm »
I have tried to convert my TDS540C to TDS580C, by take out the 4 capacitors and only short the R1064, it shows 4Gs/s, but the banner shows TDS xxx. my firmware is FV:v5.0e. 
Passed SPC.
Maybe it is the firmware version problem?

Did you try 1061 instead of 1064?
What was the original resistor configuration?
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Offline geostep

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #97 on: December 17, 2019, 10:52:59 pm »
I recently got a 540C from eBay. So you have captured my interest. It would be sweet to get it running at 1 GHz. Frustratingly I can't access it until after Christmas.    |O
So it has to sit in a box... for now.  After Christmas I'll open mine up, check my firmware version, look at the programming resistors and caps as well.

I'm hoping there is newer firmware out there that will allow 540C's with only R1064 think it is a 580C.
I'll look around and see if I can find anything about it.

- George
 

Offline Galen

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #98 on: December 17, 2019, 11:36:02 pm »
I have tried to convert my TDS540C to TDS580C, by take out the 4 capacitors and only short the R1064, it shows 4Gs/s, but the banner shows TDS xxx. my firmware is FV:v5.0e. 
Passed SPC.
Maybe it is the firmware version problem?

Did you try 1061 instead of 1064?
What was the original resistor configuration?
Thanks thm_w. The original ID resister is R1061,1062,1063 shorted.
I will try R1061 today, to see If it works.
Delighted when problem fixed
 

Offline Galen

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #99 on: December 18, 2019, 11:42:20 am »
Report the progress. short R1061 only, it shows TDS540C, the sample rate max 1G for 1 or 2 channel on.
So, I changed back to shorting R1064 only. Very possible the FW version too low.
Have to bear the 'TDS xxx' now, until upgrade the FW.
« Last Edit: December 18, 2019, 11:51:36 am by Galen »
Delighted when problem fixed
 
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Offline nctnico

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #100 on: December 18, 2019, 02:03:56 pm »
You can attach some switches and just try every combination. Perhaps you need a different combination. It is also possible that a monochrome display (I assume the TDS540C has a monochrome display) isn't supported so there is no known model number for your configuration.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline Galen

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #101 on: December 20, 2019, 06:31:48 am »
Thanks nctnico. I will need a few days to try this as time tied up these days.
The TDS580C published with the FW5.2 as stated in the tek document, so maybe the FW5.0 doesn't have the ID code for TDS580C.
But anyway, I will have a try.
Delighted when problem fixed
 

Offline Alfons

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #102 on: December 27, 2019, 03:49:49 pm »
Here is a plot that shows the frequency response of my Tek744A-784A.
The device triggers cleanly up to over 1.5GHz, the signal also looks quite good, but the frequency response is already absolutely in the basement. The -3dBm is pretty close to 1GHz. The device is not calibrated. First Picture shows 1.5GHz in ET-Sampling, last Pikture shows 1.5GHz in Real-Time-Sampling.

« Last Edit: December 27, 2019, 04:34:24 pm by Alfons »
 
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Offline Galen

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #103 on: January 07, 2020, 05:52:53 am »
Thanks nctnico. I will need a few days to try this as time tied up these days.
The TDS580C published with the FW5.2 as stated in the tek document, so maybe the FW5.0 doesn't have the ID code for TDS580C.
But anyway, I will have a try.
After I upgraded the firmware, the banner shows 'TDS580C'.  so shorting R1064 is right for TDS580C.
Delighted when problem fixed
 
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Offline Galen

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #104 on: January 11, 2020, 05:06:42 am »
Has anybody tried TDS520C or 724C upgrade?
Delighted when problem fixed
 

Offline madao

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #105 on: January 11, 2020, 07:15:53 am »
2 ch and 1 Ghz exists, but only color display model. It is called as  TDS782.   (Firmware 5.2e support also  TDS782C. )

I have a   TDS724C aquisition board as good spare part, but i wouldn't try, it is not worth.

« Last Edit: January 11, 2020, 07:20:40 am by madao »
 

Offline Galen

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #106 on: January 11, 2020, 11:57:50 am »
Thanks Matt.  I may try it someday.  but not now.
Delighted when problem fixed
 

Offline olle

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #107 on: June 04, 2020, 09:04:56 am »
Since I just noted that one of the (TDS754/784/...) acquisition board resistor configurations sets the scope to be a TDS794 (2 GHz BW on 1 channel), I wonder if anyone has tried that one out, and if so - did it work or brick the unit?

---
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Offline Jay_Diddy_BTopic starter

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #108 on: June 04, 2020, 12:09:31 pm »
Olle and the group,

Welcome to the forum!!

I have just been checking the specification of the TDS794x family, The 794 is 50 \$\Omega\$ only, which means it, (almost certainly) has different input section to the other 700 series family.

I have not seen the inside of the 794 so I don't know for certain.

Regards,
Jay_Diddy_B
 

Offline olle

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #109 on: June 04, 2020, 12:28:32 pm »
Thanks a lot for that piece of enlightenment. It means that I'll stay with my 754C-to-784C conversion for now.

 :D

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Offline Tantratron

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #110 on: March 20, 2021, 05:15:06 am »
Thanks nctnico. I will need a few days to try this as time tied up these days.
The TDS580C published with the FW5.2 as stated in the tek document, so maybe the FW5.0 doesn't have the ID code for TDS580C.
But anyway, I will have a try.
After I upgraded the firmware, the banner shows 'TDS580C'.  so shorting R1064 is right for TDS580C.
What 5.x firmware version did you flash to have banner showing TDS580C
 

Offline Pete2

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #111 on: May 03, 2023, 08:02:26 am »
I just got a 754A from Ebay. Paid too much for it because of postage and import VAT but that's the way it is. It is faulty, the infamous relays + dim CRT but at least I can retrofit an LCD if needed.

Anyway I found this topic and was considering the upgrade but I have no way to calibrate it so maybe I'll skip it for now. Also I am looking at a 754C and I assume it can have the 2M option. Is  this true? But I have to have a correct Acq board or can all of the C models support the high memory option? Any other reasons to choose 754C over 754A?
 

Offline Tantratron

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #112 on: May 12, 2023, 05:00:35 am »
Hello Pete2,

Transforming the acquisition board of a 754 into 784 requires removing 4 capacitors and lengthy re-calibration. I assume but could be wrong that if you change faulty attenuator relays will introduce some parasitic capacitance so you'll be obliged to re-calibrate the 754.

In a few words, the TDS754A or TDS784A acquisition board is the same HW as the C series, the only difference concerns logic CPU board. The A runs with 68020 whereas the C serie runs with 68040 so it is just hacking process.

What country do you reside, how does it work with intra-european import tax ?

Albert
« Last Edit: June 14, 2023, 02:56:44 am by Tantratron »
 

Offline 44kgk1lkf6u

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #113 on: February 05, 2024, 03:32:13 am »
I converted a TDS540D into a TDS580D.  It came with the jumpers R1061, R1062, and R1063.  I removed them and added R1064.  I removed the capacitors.  Then I ran signal path compensation and internal diagnostics.  Now the start-up screen shows TDS580D.  My firmware is v6.1e.  Unlike the TDS540C, I suppose any firmware that comes with revision D will be new enough.

Results.  The fastest time base went from 500 ps / div to 200 ps / div.  The fastest sample rate for a single channel went from 2 GS / s real time and 100 GS / s equivalent time to 4 GS / s real time and 250 GS / s equivalent time.  10% to 90% rise and fall times are about 250 ps at 200 mV / div and about 355 ps at 100 mV / div after the hack as measured with the measure function.  Changing the vertical scale only seems to affect the rise and fall times when it comes with a relay click.  Switching between 50 mV / div and 100 mV / div does not cause a relay to click.  The edges are about the same in those vertical scales.  Likewise the edges are similar at 200 mV / div and 500 mV / div.  To measure these I used an Onsemi NB7VQ14M CML gate to generate the square waves.  I added a 6 dB attenuator so that the waveform fits on the screen at 50 mV / div.  For coarser scales the attenuator did not seem to make a difference in the bandwidth.
 

Online David Hess

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #114 on: February 05, 2024, 04:08:48 am »
Bandwidth of the 580D and 784D decreases from 1 GHz at 10mV/div to 500 MHz at 1mV/div.
 
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Offline 44kgk1lkf6u

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #115 on: February 05, 2024, 05:54:54 am »
To be clear, the external attenuation setting was 1x in all the measurments.

I just got out a 20 dB attenuator and measured the bandwidth at larger amplification.  From 100 mV / div down to 10 mV / div, the edges are 355 ps.  At 5 mV / div, it is 400 ps.  I don't have an attenuator that makes the curve fit on the screen at 2 mV / div.

Table 1-16 in the service manual lists the rise time for the 580D and 784D as 400 ps at 10 mV / div to 1 V / div and 530 ps at 5 mV / div.  So maybe the bandwidth is even higher from 200 mV / div to 1 V / div, but they did not want to guarantee it.
 

Offline Tantratron

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Re: Conversion of 500MHz TDS744A to 1GHz TDS784A
« Reply #116 on: February 05, 2024, 05:40:44 pm »
To be clear, the external attenuation setting was 1x in all the measurments.

I just got out a 20 dB attenuator and measured the bandwidth at larger amplification.  From 100 mV / div down to 10 mV / div, the edges are 355 ps.  At 5 mV / div, it is 400 ps.  I don't have an attenuator that makes the curve fit on the screen at 2 mV / div.

Table 1-16 in the service manual lists the rise time for the 580D and 784D as 400 ps at 10 mV / div to 1 V / div and 530 ps at 5 mV / div.  So maybe the bandwidth is even higher from 200 mV / div to 1 V / div, but they did not want to guarantee it.
Sometimes it is strange with these acquisition board.

Two years ago, I've purchased a TDS784C from eBay but when I open to check, to clean the all unit then I saw the 4 capacitors so I was not happy after the Belgium seller (the 4 cap should not be there for 1 GHz). However I connected on each channel my Leo Bodnar pulser and to my surprise, the bandwidth was really as a TDS784C.

Go figure out... tekronix left the 4 capacitors normally found if TDS754C but declared as TDS784C
 


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