Conversion Tektronix TDS500 to TDS700 color oscilloscope

[zxase258]

In model TDS500B/C/D has been successfully tested.
TDS500 and 700 series, in the same model, they have the same firmware and acquisition system, and similar processor board.
Only need to add and change some components, you can change TDS500 series to TDS700 series.
Before you upgrade, you should first install the color LCD monitor via the VGA out connector.
(A similar project (Simmconn Labs) to this topic, he uses FPGA reads display memory, and "color" the data. This solution is too complicated and expensive. )
TDS520B -> TDS724A
TDS540B -> TDS754A
TDS520C -> TDS724C
TDS540C -> TDS754C
TDS580C -> TDS784C
TDS520D -> TDS724D
TDS540D -> TDS754D
TDS580D -> TDS784D

For TDS500B series(All changes are on the processor board).
remove:R12(model ID) R151 & R152 & R153
replace:U251 74F04 to U250
install:U837 & U835 & U836 & U834       TC528257J-70   Video RAM













For TDS500C/D series(All changes are on the processor board).
It has been a long time since I finished this work. I have forgotten which resistors I changed (for the model ID).
The following two pictures are used to compare their differences, please try it yourself.
replace:U251 74F04 to U250
install:U834 & U835 & U836 & U837       TC528257J-70 or M548263-60J   Video RAM

















Soldering SOJ packages is a bit difficult, make sure they are soldered reliably. Otherwise there will be a vertical line or flashing display.





enjoy it. 

[Jwalling]

I always knew this was possible, but I never attempted it as it was way too much work given what these are worth now!
You sir, get a high-five!

If your scope has an acquisition raw board (700C/D and 500C/D I think) that only has 64Kb SRAMs and that's capable of using 1Mb SRAMS, your next mission could be to replace all the memory and get option 2M!   

[chihaxinh]

Hi zxase258

I have one osc 520B like you . Scope have error Display and can't complate boot , can you share me your firmware of TDS 520B ?

And when hacking mod 520B to 724A only replace position resistor ?

Thank so much !
Nam Nguyen Hai

[zxase258]

Sorry, TDS520B transformation completed in 2015, at that time I do not know the firmware can be backed up. Later this scope was sold by me.
Of course, in my experience, the oscilloscope's firmware is rarely damaged. Can you talk about the symptoms?

[zxase258]

The principle should be feasible, but to solder a lot of SRAM chips, some difficulties, and SRAM prices are not cheap.
For the DPO series, fv6.6 firmware (or higher) is shipped from the factory and 2M optional SRAMs are normally installed, so these models can be directly enabled with the 2M option.

[chihaxinh]

Hi zxase258

My scope fail display PCB , i disconnect connector from main pcb to display pcb, and using LCD external . Display in boot process very slow and display green color . No relay clicking , and no led front panel blinking. Boot process not complate

Many tks you !
Nam.

[induzer]

I did a conversion of my TDS540D to TDS754D some weeks ago.
I can state the modifications zxase258 wrote to be partly correct, but maybe not complete.

Adding the VRAM - soldering was easier I thought.

Swapping U251 to U250 - rubbish on CRT (like lost sync, ic handles some picture timing signal, see service manual), no picture on VGA [timing critical part, my replacement ic was some nanoseconds too slow  ]

Swap back 250/251 - i belive it was white blank on CRT, but colour scope screen on VGA.

So far, fine.
But the scope boots up with one minor error about missing or wrong VRAM registers. Think there is some further action needed.
Maybe its missing the circuitry for the NuColor shutter system, a QFP and 3  VRAM-like footprints in the video section are not populated. Factory 745D have them populated.

serial boot debug:

dsyPM011RegMem ................. ***FAIL*** ..error details:
ERRORID: 163 diagnostic test failure dsyPM011RegMem ** addr = 0x75ed808  exp data = 0x7f00  actual = 0xff00
Failure in first PM011 vdramal register

Apart from that and after replacing a brick CAL-EEPROM and recalibration, the scope works fine with a 19" color screen via the rear VGA port.

Lucky me, so I can read the screen without my glasses, which I often set off while debugging

greeting, induzer   

[induzer]

Had a quick look at the schematics.

It's definite the missing frame buffers VRAMs U820 to U822 and the ASIC U2011 (National ADG281)

U822 is also called PM011, see my fault code in the last post. Missed that until now 


So the following Parts need to be modified for 540D to 754D conversion (all on CPU board):

- CHANGE the ID resistors like shown in picture and table

- INSERT U834 & U835 & U836 & U837 + U820 & U821 & U822 == TC528257J-70 or M548263-60J   Video RAM

- TRY REMOVE U251 == 74F04
- TRY INSERT U250 == 74F04 (use fast ic or save U251)
  (crt picture, see my earlier experiences)

- INSERT U2011 == ADG281 == MM9351-VCE

If you can live with error an selftest and are happy with external screen only, leave U2011 & U820 & U821 & U822 open.
As far as I can speak for my own scope, it does not affect the meaurement.


Maybe someone will proof that I got confused while playing around with U250 / U251 for saving the internal screen functional.

induzer

[PerpetualWalnut]

Do you know any good places to find the vram chips and the ASIC? I guess I could wait and find a fried 754C CPU board on ebay.

I also tried just changing the jumper settings without the other mods and it boots up as the 754C with a flashing color screen on the VGA output and a completly white CRT the first time I booted it up, then on the second time I booted it up the CRT was mostly white but had the text on display.

[PerpetualWalnut]

Okay! I've substituted the TC528257J-70 vram chips with TC528267J-60 and it works just fine. The TC528267J-60 chips where half the price on ebay. As for the ASIC I haven't been able to get one yet. The scope powers on in 754 mode with the built in CRT displaying Text on white background with no waveform, and the VGA out displays full color without error.

It does fail the processor self test when run manually but everything else seem to work fine. I guess this might have something to do with the missing ASIC chip. Maybe if someone here has a dead board they are willing to de-solder one of the ASICs and send one my way? Ill buy! Plus beer if your in the DFW area.

I guess I would also need U193. Lots of NOS tlc34075 on ebay from what it looks like!

I should also add that moving U251 to U250 causes the internal display to go out of sync while doing nothing for the VGA output. So for now I'm just going to leave it at U251. The Internal display is white but the VGA output is still in color. LUCKILY! Putting the jumper resistors back to the 540C config allows it to work fine even after adding the addition ram chips!

[PerpetualWalnut]

So!! I switched out and installed U193 and now nothing appears on the built in CRT but the VGA out still works.  I probably still need the ASIC, probably. I also need U260 which is a 74F08. Weird that they depict it in the schematics as a NOR gate with inverted inputs. Does the same thing though.  I went ahead and ordered a couple off digikey and should be here within the week. They can hitch a ride with my LED COB WHT 5600K 95CRI 1214-1267-ND for anyone interested, but that's for another project. Hope this helps anyone else. My goal is to have a converted TDS 754 that still has a functioning CRT with the option of upgrading to a color CRT or LCD swap in the future. I could do an LCD swap now, but that's boring.

[zxase258]

Had a quick look at the schematics.

It's definite the missing frame buffers VRAMs U820 to U822 and the ASIC U2011 (National ADG281)

U822 is also called PM011, see my fault code in the last post. Missed that until now 


So the following Parts need to be modified for 540D to 754D conversion (all on CPU board):

- CHANGE the ID resistors like shown in picture and table

- INSERT U834 & U835 & U836 & U837 + U820 & U821 & U822 == TC528257J-70 or M548263-60J   Video RAM

- TRY REMOVE U251 == 74F04
- TRY INSERT U250 == 74F04 (use fast ic or save U251)
  (crt picture, see my earlier experiences)

- INSERT U2011 == ADG281 == MM9351-VCE

If you can live with error an selftest and are happy with external screen only, leave U2011 & U820 & U821 & U822 open.
As far as I can speak for my own scope, it does not affect the meaurement.


Maybe someone will proof that I got confused while playing around with U250 / U251 for saving the internal screen functional.

induzer

According to my tests, the ADG281 is not a required component and it is connected to the TLC34075. The TLC34075 is only used to generate the sync signal required by the NuColor LCD shutter. Even if you do not install ADG281, TLC34075, and VRAM associated with TLC34075, the oscilloscope can PASSED self-test

[zxase258]

Okay! I've substituted the TC528257J-70 vram chips with TC528267J-60 and it works just fine. The TC528267J-60 chips where half the price on ebay. As for the ASIC I haven't been able to get one yet. The scope powers on in 754 mode with the built in CRT displaying Text on white background with no waveform, and the VGA out displays full color without error.

It does fail the processor self test when run manually but everything else seem to work fine. I guess this might have something to do with the missing ASIC chip. Maybe if someone here has a dead board they are willing to de-solder one of the ASICs and send one my way? Ill buy! Plus beer if your in the DFW area.

I guess I would also need U193. Lots of NOS tlc34075 on ebay from what it looks like!

I should also add that moving U251 to U250 causes the internal display to go out of sync while doing nothing for the VGA output. So for now I'm just going to leave it at U251. The Internal display is white but the VGA output is still in color. LUCKILY! Putting the jumper resistors back to the 540C config allows it to work fine even after adding the addition ram chips!

Please check your oscilloscope ERROR LOG, if there is something like DsyMem, there are some broken bits in the newly installed VRAM. These chips are very likely to be junk, especially if the sellers selling them are located in mainland China or Hong Kong.
I am very sorry that my post was a bit sloppy. I didn't take notes in detail after I worked. It may have some errors, but I can be sure that if the VRAM is not faulty, even if the ASIC is missing, the oscilloscope can pass the self-test.

[madao]

A member from here have modified  TDS580D to  TDS784D with sucess. It is full modification with ADG281 to avoid error message and is capable to driving  NuColor-CRT.


I have here  4 piece ADG281 left. It came from dead TDS540A.
Let me know, if you need it. You can get it for shipping cost and donation. (loc. germany)

Spots on one ADG281 is flux odds

greeting
matt

[Tantratron]

Maybe someone could verify this new test I've done.

Connected a color external display (DELL) to my TDS540C (black and white) via the video connector.

When I boot, both displays show the same thing except during 1 or 2 seconds, the external display shows different colors. Then the external display shifts to black and white but my question, is there a way to block or disable the firmware so the TDS540C with external display becomes a TDS754C ?

Thanks, Albert

[PerpetualWalnut]

Are you still selling those ADG281? I would be more than happy to take one off your hands! I can PM you my address and we can work something out for shipping from there. Thanks in advance!

[madao]

Now is  3 pieces  ADG281  avaible.

But i must make a notice:  Shipping from germany to  non EU-contries cost now  16€ (~ US$ 17-18 , german post  )

[madao]

Are you still selling those ADG281? I would be more than happy to take one off your hands! I can PM you my address and we can work something out for shipping from there. Thanks in advance!

Pleas clear your message box, your is full.

I answer here: for 16€ shipping from germany to  foreign country: no tracking.   German post , shame oneself !

[PerpetualWalnut]

Got it, thanks again. I cleared my messages.

[PerpetualWalnut]

Maybe someone could verify this new test I've done.

Connected a color external display (DELL) to my TDS540C (black and white) via the video connector.

When I boot, both displays show the same thing except during 1 or 2 seconds, the external display shows different colors. Then the external display shifts to black and white but my question, is there a way to block or disable the firmware so the TDS540C with external display becomes a TDS754C ?

Thanks, Albert

You would probably have to wire in a switch to get it to do that. I'm currently working on getting my b/w internal display to work properly in 754 mode along with color output on the external VGA port. That's why I wanted the ASIC from madao, I wanted to see if I could get the color sync signals to work with the B/W display. In 754 mode it doesn't appear to generate the proper sync signals with stock hardware for the internal B/W CRT. The advantage to this would be that I could swap in nucolor hardware if my internal CRT ever kicks the bucket along with the option of changing it to a VGA LCD. More options, more reliability. Ill post again when I get the ASIC in the mail.

[capt bullshot]

Got some promising results - I'm able to use an external VGA monitor in colour (TDS784) mode while preserving the original TDS580C internal B/W display.

What did I do:

Thanks to madao, I've received a ADG281 ASIC, and some VRAMs (TC528267J-70) from an American ebay seller. Following most of this threads instructions, I soldered the ASIC and seven VRAM chips to the CPU board, replaced U251 to U250, and removed the ID resistor to change the model to TDS784. This works and results in a non-synchronized internal display (as someone pointed out before). Placing U250 back to U251 brought the internal display back to sync, but didn't display a useful picture (as pointed out before). Since I didn't replace U190 by U193 (TLC34075, the RAMDAC for the NuColor internal display), the Display self test results in a failure indicating U193 (go figure ).

Now, what happens: U199 provides the VGA output for all (colour and B/W models), this works. U190 provides the internal display output in B/W models, and doesn't if a colour model is selected. Turns out, its colour palette registers never get written by the firmware in colour mode (why should the fw do so, since this chip isn't present in colour models). So the palette register have some random content after power on, resulting in an unusable display. Anyway, this leads to simple fix: Remove U190 pin 16 (\WR) from the signal WDAC1*\I and connect this pin in parallel to U199 pin 16 (WDAC2*\I). Now both RAMDACs get written with the same contents, so U190 outputs the same video contents as U199 does to the external memory. In a second step, remove FSYNC/VIDEO*\I from pin 25 (red output) and connect this signal to pin 26 (green output).

Voila: The internal display shows a useful picture with the monochrome palette selected from the menu (the external monitor shows all traces in green in this mode). One can edit the colours to display the traces at different brightness levels.

As said before, the ADG281 and three VRAMs aren't required for this to work, one requires them if a real NuColor display is to be connected. In this case, one has to replace U190 by U193 also, move U251 to U250 and populate U260. Since I don't have a NuColor display, I cannot verify this.

[Jwalling]

What did I do:

You guys are NUTS! (but in a good way...)

[PerpetualWalnut]

Update on my TDS540

Thanks again for the ASIC madao! Works great!

I was able to successfully do a full NuColor conversion of my TDS540 to TDS754 scope! I bought a $200 "AS-IS" TDS754 off ebay and used the CRT and LCD shutter out of it to test my board. Unfortunately the ebay listing didn't say anything about a missing CRT driver board... So I got back on ebay and came across 5 CRT driver boards for $20 plus another $20 in shipping! They where AS-IS as well, but for $40 I figured I could get at least one working, but that's for later.

The CRTs... The one that came with my TDS754 as badly faded, but the LCD shutter worked. I decided to try the old CRT rejuvenation trick on both of the CRTs that I now had. At first it seemed to work on my 540 CRT, but the 754's CRT was being stubborn. It had a little improvement, but not much. I figured it was toast so I got out the MOT and variac and *POP* there goes the cathode! oops At least I got a major improvement from my old CRT. I decided to cut the LCD shutter off the popped CRT and see if I could use it with my old but working CRT. I was able to get that to work by taking the yoke off the popped CRT and putting it on the working one, but the pinout of the working CRT was turned 90 degrees in relation to the popped CRT so I had to improvise an adapter using the connector from my B&W CRT driver board. This worked and I could now fit it into my scope!... The bracket on the face of both CRTs are different. See pics. I did end up swapping by *carefully* cutting both off with a drimmel and using some double sided tape to stick it back on. This kinda works but now the mounting holes don't line up!  Anyhow, Ill deal with that later. Right now I want to test my driver boards.

3 of them works! 1 only show B&W, and the last one has a short. Not bad for $40! Ill resale them after I repair and test them.

As for finishing the 540 to 754 conversion, see pics. There are a few resistors and one or two caps on the BACK of the board that needs to be swapped around or added! And don't over heat your board like I did to mine when I was swapping out U193 with a few different chips because I couldn't figure out why it wasn't work. Turns out it was the resistors on the back of the board... Anyways! Hope you enjoy!

[PerpetualWalnut]

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[PerpetualWalnut]

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