Author Topic: Conversion of 500MHz TDS744A to 1GHz TDS784A  (Read 77354 times)

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Online 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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