Author Topic: Reverse engineering Tektronix TDS3GV module for TDS3000 series oscilloscopes?  (Read 1794 times)

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Offline Icchan

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Hi everyone.

I've had a possession of older Tektronix TDS3032 oscilloscope for some years. It's good unit, but the lack of any expansion cards is starting to drive me crazy. I have a floppy drive (which I'm thinking to replace with floppy emulator), but RS232/VGA/GPIB option card would be a god send.

Unfortunately TDS3GV module is prohibitively expensive. It's hundreds of Euros used, and with that mount of money, one should already buy new Rigol or something else and that would be money better spent.

http://uk.rs-online.com/web/p/oscilloscope-modules/4136989/

I spent some time Googling if anyone has reverse engineered or even opened the module and if it's in any way feasible as a project to create OSH replacement for this. But found nothing.

I wonder if any forum members have aforementioned module that they could open up and photograph at least? that would at least give some idea if there's any sense even considering the idea.

Thanks for any input about this :)
« Last Edit: December 07, 2016, 10:05:45 am by Icchan »
 

Offline Jwalling

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Here you go.
Jay

System error. Strike any user to continue.
 

Offline james_s

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This is a very old thread but I just found it today. Fascinating, there's very little in those, it can almost be reverse engineered just from a photo. The VGA is as I suspected just a DAC which is almost certainly fed by the same signals that go to the internal LCD. The RS232 looks like just some buffers and a level shifter. The GPIB uses an off the shelf GPIB interface IC.

Just having the pinout for the RS232 portion would make it easy to replicate that part which is all I really need.
 

Offline pmercier

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Hi,

can't agree more with you jame_s. I have two of the TDS3000 at home and started to wan't at least a serial interface.

I started to map the connector pinout around april and can confirm that the LCD lines are more or less directly connected to it.

The serial lines seem to be around the middle of the connector but hadn't time to confirm it.
 

Offline james_s

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Well I ended up just buying one of these things myself, at $240 it was more than I had invested in the whole scope but I'm still ahead in the grand scheme of things. Time permitting I'll reverse engineer the serial portion, that alone is enough to do the bandwidth unlock amongst other things.
 

Offline alba800

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That would be a great thing. I'm waiting for you to have time to map the serial signals pinout.

many thanks
 

Offline james_s

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I've been swamped with my day job lately, on top of some house maintenance. I have not forgotten though, the scope with its comm module are sitting in the middle of my workbench awaiting a closer look.
 
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Offline fqahmad66

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its probably a four layered pcb. hard to replicate.
 

Offline james_s

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Not really, 4 layer boards aren't that big a deal anymore but I'm pretty sure it's only a regular double sided board. Not really relevant anyway since the only portion needed is the RS232 interface and there's only a handful of parts in that. 
 

Offline james_s

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Ok so it turns out this *is* a 4 layer board, that didn't end up being too much of an obstacle though. Tonight I sat down and went through the serial part and mapped out the pins at each end. I'm pretty confident this is correct but the usual disclaimers apply, use this information at your own risk, I'm not going to take responsibility if you fry your scope.

I haven't taken the time to draw up a schematic but the serial portion is trivial enough that this shouldn't even be necessary. The DB9 connector has TXD, RXD, CTS, RTS, DTR and DSR wired to the MAX2386 through what looks like some ESD protection, the capacitors are wired from each pin to ground. Curiously DTR is tied to ground on the input side (pin 19) of the level shifter and DSR (pin 22) is floating. The four signals that are used pass through 100R resistors directly to pins on the 100 pin connector, I don't know specifically what this connector is but has the AMP logo on it and looks like what I've seen called HiRose connectors. I don't know how the pin numbering is arranged so I've marked on the picture where all the signals go.

I've marked all of the ground pins, obviously they are not all involved in the serial interface however I suspect (and hope) the scope identifies the installed module by something as simple as grounding the right pins. If somebody decides to clone the serial interface using this information please do share the results.

 
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Offline pmercier

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The 100pins connector can be replaced by a standard 1.6mm pcb. It fit inside without a problem.
Thank you for the serial mapping.
 

Offline pmercier

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Found my old notes from pocking inside the scope and it triggered an heavy desire to loose some sleeping hours ;)

Looking at the pins you marked as ground, I've found the same ones for ground on the scope motherboard.

Found the board connector (hope i got the good one) and ordered a testing PCB. Am actually waiting for both of them to arrive.

From what i found when pocking around :

* The screen signal from the J500 connector is present on the extension connector directly (Don't think i'll do something with it, but ... can be fun to play with it later)
* Data (16) and address bus is accessible (found only 11 lines for the moment)
* Something that i need to check again : RTS is connected to the *WR ... seem odd
 

Offline pmercier

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Offline james_s

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Oh there you go, yeah that looks right, AMP 1-1734099-0, good find. It's not even very expensive, I'd buy one myself but I already have the original module so not much to be gained in duplicating the work of others.

If all the ground pins I marked are ground on the motherboard then I wonder how it detects that the module is installed? If wiring up a comm port doesn't just work I'll have to take another look and see if I can find any likely suspects. The serial settings are not disabled without a comm module but it does definitely know when it's there and list it on the boot screen.

Yeah the video I assume is just the exact same signals that go to the TFT, I've used the similar ADV7123 VGA DAC before and it accepts exactly the same digital RGB/H/V/Dotclock signal as these older TFT displays. I have a VGA output on my other scope and I've never actually used it, the built in display has always been adequate for me.

Makes sense that the data and address bus would be there, the GPIB interface would need that. Does sound odd about RTS going to WR, if it doesn't work I can take it apart again and double check but I'm pretty confident I got the pins traced out correctly.
 

Offline pmercier

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Little update. Received the connnectors today. They're a perfect match.
I soldered dupond wires for the 3.3v serial/usb module directly on the provided pins and ... worked like a charm once i removed the hardware control flow from the scope config.

Sended : *IDN?
Got : TEKTRONIX,TDS 3032C,0,CF:91.1CT FV:v4.05 TDS3FFT:v1.00 TDS3TRG:v1.00

 :-+


 
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Offline ArcticGeek

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@pmercier

Nice work.

Can you clarify what the wires you soldered on were connected to?   I assume these were the serial connections that you soldered:  TX, RX, CTS, and RTS....is that correct?   And these wires were then connected to some sort of TTL/RS232 level translator IC?

Mike
 

Offline james_s

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Woohoo!

Would have saved me $250 (well, $230 by the time I bought a connector) to know that but somebody had to do it. Glad to hear it works and is really that simple.

The wires are soldered to TXD, RXD, CTS and RTS, refer to my screenshot of the bottom of the board where it is labeled.

The signals are 3.3V logic so you will need something like a MAX232 or one of those USB to LVTTL serial modules. They go direct to the CPU or one of the ASICs so I highly recommend some ESD protection as was incorporated in the original comm module. 

Downgrade to firmware 3.39 and then send the following:
        PASSWORD PITBULL
        MCONFIG TDS3054

Power cycle and it should boot up saying it's a TDS3054B. Run SPC and you should be good to go.

You can then update to the latest firmware and run SPC again.

Actually I believe the B models can go all the way up to TDS3064 which is 600MHz 5GS/sec. Mine is a TDS3014 (no letter) so I was "only" able to upgrade it to 500MHz.
« Last Edit: October 21, 2019, 11:29:06 pm by james_s »
 


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