Tektronix TDS520B Hack / Upgrade to TDS620B ?

[sorenkir]

Hello group,

I have seen interesting hack/upgrade data in the following thread :
https://www.eevblog.com/forum/testgear/tek-tds-3054b-vs-tds-744a/

I have a TDS520B, 2 channels 500MHZ 1GS/s. I think I could see if an "upgrade" to TDS620B (same BW and number of channels but better sampling rate) is possible.

Configuration resistors for TDS520B on acquisition board are (see photo):
BID0=R1061 missing, BID1=R1062 soldered, BID2=R1063 missing, BID3=R1064 soldered --> 1010

Configuration resistors on processor board are (see other photo):
ID0=R17 soldered, ID1=R15 missing, ID2=R13 missing, ID3=R12 soldered --> 0110
NVSIZE0=R9 soldered, NVSIZE1=R7 soldered --> 00

(signal names as per TDS520B Component Service Manual pdf p269 & 297)

I had no chance with finding board pictures for TDS620B on Google.
Does anyone by chance have this configuration resistors data or photos of acquisition board (bottom side) & processor board ?

Thanks,
Michel.

[nctnico]

These scopes are completely different so I strongly doubt such a hack is possible. The TDS600 series are realtime sampling oscilloscopes with very short memories.

[sorenkir]

nctnico, I think you are right on the architecture point.

Anyway, TDS520B has 2 samplers operating each @ 500MS/s. Maybe there is a configuration that allows them to operate @ 1GS/s (that's what happens when a TDS744A, 4 samplers @ 500MS/s, "becomes" a TDS784A, 4 samplers @ 1GS/s, as some reported in the other thread) ?

Unfortunately, that config. does not seem to correspond to any model. So maybe a dead end  .

Michel.

[sorenkir]

Hello,

I have seen on the photos of a TDS724A acquisition board that the configuration resistors are exactly the same as for my TDS520B (in this post:  TDS 724A saga, dead H2462H, many questions, please help !!! ) !

So the complete model definition probably includes the processor board configuration...

Does anyone have a close-up of the configuration resistors (R12 to R17 near U2000) of the processor board of a TDS 724A ?

Thanks in advance,
Michel.

[nctnico]

Attach a dip switch and try the combinations to see if the firmware in your oscilloscope supports other models.

[sorenkir]

Hi,

I have tried to remove R12 on processor board which seems the only difference between a TDS520B configuration and a TDS724A (apart from colour display hardware which is not present in TDS520B). The acquisition board is the same with the same configuration resistors.
The scope booted with a banner indicating TDS724A. But the display had some parts blinking quickly.
Also, the acquisition and position control were inoperative. The limitation to two live channels remains. Plus a truncated nvram related message in the error log (WARNING: 600 remote nv memory ac...).

So, there must be something else (but I have tried !)...

Michel.

[tinhead]

the only diff between TDS520B and TDS724A are on processor board and in nvram (TDS5 enabled/disabled). So when you already playing, try the next model, TDS782A. Change the processor board first back to TDS520B and then acq board from 5 to 1, maybe the firmware will not check the nvram anymore.

[sorenkir]

Hello,

I have tried what tinhead suggested : processor board as TDS520B and acquisition board as TDS782A (by adding a strap on R1063 --> acq id=1).
I managed to have a TDS xxx on the banner screen !
This model is capable of 2GS/s with only one channel active (whereas TDS520B goes only to 1GS/s). That's what I was expecting.
But :
The two DACs do not interleave properly at 2GS/s, see photo. Calibration is required...
A side effect of this configuration is that the TDS xxx is not recognized by the WaveStar software  .
I don't think that a 2 channels monochrome model with 2GS/s acquisition capabilty exists, so I fear that no solution exists for this issue.

Michel.