Teardown : Tektronix TCA-1MEG high-impedance amplifier for TekConnect

[TiN]

High-end Tektronix (series 7000/70000) have proprietary TekConnect HF inputs, which accept only 50 ohm inputs.
This limits usage of such scopes only to special (read - expensive) TekConnect active probes.

Also using DIY is not a simple forward path either, as even simple passive adapter from TekConnect to BNC or SMA (TCA-BNC, TNC-SMA) cost few hundreds USD on ebay easy!

If you want use 1 Meg input impedance options even more limited, with Tek's offering of TCA-1MEG amplifier, which costs ~500$ used.

Was lucky to get one of these relatively cheap, so here's a teardown (article per image link):

[MSS]

Nice work! I want to make such probe adaper. Have you any ideas about it? Have you trace the connection between scope and that "blac-box" ic with heat sink on it?

[David Hess]

In its basic form it comes down to a high impedance buffer stage followed by a x2 amplifier to drive a double termination which is how an active probe could work.  But usually an active probe would do away with the amplifier and use x10 total attenuation instead.  High impedance oscilloscope input circuits work the same way so there is another source of examples.

[charlyd]

i  bought this TCA-1MEG adapter and after connecting
it gives "fail".  does any have experience with these failed
adapters ? i saw it was a 24C16 behind a expander chip.
can it be a corrupt content ? or ?

the seller didn t want to take it back 
help or donor unit wanted

i will open up new post.
https://www.eevblog.com/forum/testgear/tektronix-tca-1meg/msg3801434/#msg3801434

[dxl]

Was lucky to get one of these relatively cheap, so here's a teardown (article per image link):

And here's the eeprom content "teardown"

Code: [Select]

@000b T03/Lb   Elements requiring support: 1A 08
@0016 T27/L6   Current draw ?
@001c T16/L6   Input Resistance: 1.0e+06Ohm
@0022 T18/L6   Input Capacitance: 1.0e-11F
@0028 T1b/L6   Max operatingc range 100V
@002e T02/L13  Model: TCA-1MEG Serial: B010368
@0041 T26/L4   Tekprobe version: 3/3
@0045 T12/L6   Insert Delay: 1.8e-09s
@004b T51/L4   cascade capable: 0/0
@004f T22/L12 
@0053         T08/L5   IO Expander: 70 01 00
@0058         T03/L9   Elements requiring support: 1E 01
@005c                 T08/L5   IO Expander: 70 01 01
@0061 T22/L271
@0066         T0a/L1   Type 0a:
@0067         T25/La   Scale min: 1.0e+00, max 1.1e+00
@0071         T22/Lbb 
@0076                 T14/L6   Lowpass:  20Mhz
@007c                 T46/L8   Type 46: 01 00 4F E8 F5 BC
@0084                 T46/L8   Type 46: 01 01 14 3F 82 3F
@008c                 T15/L4   Post compensation: 00 0F
@0090                 T07/L22  I2C-7: 70 FE 48 00 C8 01 48 01 00 00 80 01 00 00 30 00 B0 01 30 00 40 00 C0 01 40 00 66 00 E6 01 66 00
@00b2                 T06/L3d 
@00b3                         T14/L6   Lowpass: 100Mhz
@00b9                         T46/L8   Type 46: 01 00 15 1B F3 BC
@00c1                         T46/L8   Type 46: 01 01 69 52 82 3F
@00c9                         T15/L4   Post compensation: 01 0F
@00cd                         T07/L22  I2C-7: 70 FE 48 00 C8 01 48 01 08 00 88 01 08 00 30 00 B0 01 30 00 40 00 C0 01 40 00 66 00 E6 01 66 00
@00ef                 T06/L3d 
@00f0                         T14/L6   Lowpass: 500Mhz
@00f6                         T46/L8   Type 46: 01 00 78 09 CE BC
@00fe                         T46/L8   Type 46: 01 01 08 3D 83 3F
@0106                         T15/L4   Post compensation: 02 0F
@010a                         T07/L22  I2C-7: 70 FE 48 00 C8 01 48 01 10 00 90 01 10 00 30 00 B0 01 30 00 40 00 C0 01 40 00 66 00 E6 01 66 00
@012c         T06/Ld3 
@012e                 T10/L6   Scale 10.0
@0134                 T25/La   Scale min: 8.0e-01, max 1.0e+00
@013e                 T12/L6   Insert Delay: 1.4e-10s
@0144                 T22/Lbb 
@0149                         T14/L6   Lowpass:  20Mhz
@014f                         T46/L8   Type 46: 01 00 8C 69 A6 BC
@0157                         T46/L8   Type 46: 01 01 92 E6 6B 3F
@015f                         T15/L4   Post compensation: 03 0F
@0163                         T07/L22  I2C-7: 70 FE 54 00 D4 01 54 01 04 00 84 01 04 00 2E 00 AE 01 2E 00 44 00 C4 01 44 00 66 00 E6 01 66 00
@0185                         T06/L3d 
@0186                                 T14/L6   Lowpass: 100Mhz
@018c                                 T46/L8   Type 46: 01 00 75 CA A3 BC
@0194                                 T46/L8   Type 46: 01 01 59 FB 6B 3F
@019c                                 T15/L4   Post compensation: 04 0F
@01a0                                 T07/L22  I2C-7: 70 FE 54 00 D4 01 54 01 0C 00 8C 01 0C 00 2E 00 AE 01 2E 00 44 00 C4 01 44 00 66 00 E6 01 66 00
@01c2                         T06/L3d 
@01c3                                 T14/L6   Lowpass: 500Mhz
@01c9                                 T46/L8   Type 46: 01 00 C0 B0 7C BC
@01d1                                 T46/L8   Type 46: 01 01 0B B6 6D 3F
@01d9                                 T15/L4   Post compensation: 05 0F
@01dd                                 T07/L22  I2C-7: 70 FE 54 00 D4 01 54 01 14 00 94 01 14 00 2E 00 AE 01 2E 00 44 00 C4 01 44 00 66 00 E6 01 66 00
@01ff         T06/Ld3 
@0201                 T10/L6   Scale 100.0
@0207                 T25/La   Scale min: 7.0e-01, max 1.0e+00
@0211                 T12/L6   Insert Delay: 2.6e-10s
@0217                 T22/Lbb 
@021c                         T14/L6   Lowpass:  20Mhz
@0222                         T46/L8   Type 46: 01 00 A2 D0 B2 BC
@022a                         T46/L8   Type 46: 01 01 02 D9 6B 3F
@0232                         T15/L4   Post compensation: 06 0F
@0236                         T07/L22  I2C-7: 70 FE 52 00 D2 01 52 01 02 00 82 01 02 00 2E 00 AE 01 2E 00 42 00 C2 01 42 00 66 00 E6 01 66 00
@0258                         T06/L3d 
@0259                                 T14/L6   Lowpass: 100Mhz
@025f                                 T46/L8   Type 46: 01 00 41 2B B0 BC
@0267                                 T46/L8   Type 46: 01 01 FF 03 6C 3F
@026f                                 T15/L4   Post compensation: 07 0F
@0273                                 T07/L22  I2C-7: 70 FE 52 00 D2 01 52 01 0A 00 8A 01 0A 00 2E 00 AE 01 2E 00 42 00 C2 01 42 00 66 00 E6 01 66 00
@0295                         T06/L3d 
@0296                                 T14/L6   Lowpass: 500Mhz
@029c                                 T46/L8   Type 46: 01 00 30 F2 B2 BC
@02a4                                 T46/L8   Type 46: 01 01 BA D9 6B 3F
@02ac                                 T15/L4   Post compensation: 08 0F
@02b0                                 T07/L22  I2C-7: 70 FE 52 00 D2 01 52 01 12 00 92 01 12 00 2E 00 AE 01 2E 00 42 00 C2 01 42 00 66 00 E6 01 66 00
@02d2 T1a/L6   Dynamic range +/-1.000V


[ddrl46]

Was lucky to get one of these relatively cheap, so here's a teardown (article per image link):

And here's the eeprom content "teardown"

Code: [Select]

@000b T03/Lb   Elements requiring support: 1A 08
@0016 T27/L6   Current draw ?
@001c T16/L6   Input Resistance: 1.0e+06Ohm
@0022 T18/L6   Input Capacitance: 1.0e-11F
@0028 T1b/L6   Max operatingc range 100V
@002e T02/L13  Model: TCA-1MEG Serial: B010368
@0041 T26/L4   Tekprobe version: 3/3
@0045 T12/L6   Insert Delay: 1.8e-09s
@004b T51/L4   cascade capable: 0/0
@004f T22/L12 
@0053         T08/L5   IO Expander: 70 01 00
@0058         T03/L9   Elements requiring support: 1E 01
@005c                 T08/L5   IO Expander: 70 01 01
@0061 T22/L271
@0066         T0a/L1   Type 0a:
@0067         T25/La   Scale min: 1.0e+00, max 1.1e+00
@0071         T22/Lbb 
@0076                 T14/L6   Lowpass:  20Mhz
@007c                 T46/L8   Type 46: 01 00 4F E8 F5 BC
@0084                 T46/L8   Type 46: 01 01 14 3F 82 3F
@008c                 T15/L4   Post compensation: 00 0F
@0090                 T07/L22  I2C-7: 70 FE 48 00 C8 01 48 01 00 00 80 01 00 00 30 00 B0 01 30 00 40 00 C0 01 40 00 66 00 E6 01 66 00
@00b2                 T06/L3d 
@00b3                         T14/L6   Lowpass: 100Mhz
@00b9                         T46/L8   Type 46: 01 00 15 1B F3 BC
@00c1                         T46/L8   Type 46: 01 01 69 52 82 3F
@00c9                         T15/L4   Post compensation: 01 0F
@00cd                         T07/L22  I2C-7: 70 FE 48 00 C8 01 48 01 08 00 88 01 08 00 30 00 B0 01 30 00 40 00 C0 01 40 00 66 00 E6 01 66 00
@00ef                 T06/L3d 
@00f0                         T14/L6   Lowpass: 500Mhz
@00f6                         T46/L8   Type 46: 01 00 78 09 CE BC
@00fe                         T46/L8   Type 46: 01 01 08 3D 83 3F
@0106                         T15/L4   Post compensation: 02 0F
@010a                         T07/L22  I2C-7: 70 FE 48 00 C8 01 48 01 10 00 90 01 10 00 30 00 B0 01 30 00 40 00 C0 01 40 00 66 00 E6 01 66 00
@012c         T06/Ld3 
@012e                 T10/L6   Scale 10.0
@0134                 T25/La   Scale min: 8.0e-01, max 1.0e+00
@013e                 T12/L6   Insert Delay: 1.4e-10s
@0144                 T22/Lbb 
@0149                         T14/L6   Lowpass:  20Mhz
@014f                         T46/L8   Type 46: 01 00 8C 69 A6 BC
@0157                         T46/L8   Type 46: 01 01 92 E6 6B 3F
@015f                         T15/L4   Post compensation: 03 0F
@0163                         T07/L22  I2C-7: 70 FE 54 00 D4 01 54 01 04 00 84 01 04 00 2E 00 AE 01 2E 00 44 00 C4 01 44 00 66 00 E6 01 66 00
@0185                         T06/L3d 
@0186                                 T14/L6   Lowpass: 100Mhz
@018c                                 T46/L8   Type 46: 01 00 75 CA A3 BC
@0194                                 T46/L8   Type 46: 01 01 59 FB 6B 3F
@019c                                 T15/L4   Post compensation: 04 0F
@01a0                                 T07/L22  I2C-7: 70 FE 54 00 D4 01 54 01 0C 00 8C 01 0C 00 2E 00 AE 01 2E 00 44 00 C4 01 44 00 66 00 E6 01 66 00
@01c2                         T06/L3d 
@01c3                                 T14/L6   Lowpass: 500Mhz
@01c9                                 T46/L8   Type 46: 01 00 C0 B0 7C BC
@01d1                                 T46/L8   Type 46: 01 01 0B B6 6D 3F
@01d9                                 T15/L4   Post compensation: 05 0F
@01dd                                 T07/L22  I2C-7: 70 FE 54 00 D4 01 54 01 14 00 94 01 14 00 2E 00 AE 01 2E 00 44 00 C4 01 44 00 66 00 E6 01 66 00
@01ff         T06/Ld3 
@0201                 T10/L6   Scale 100.0
@0207                 T25/La   Scale min: 7.0e-01, max 1.0e+00
@0211                 T12/L6   Insert Delay: 2.6e-10s
@0217                 T22/Lbb 
@021c                         T14/L6   Lowpass:  20Mhz
@0222                         T46/L8   Type 46: 01 00 A2 D0 B2 BC
@022a                         T46/L8   Type 46: 01 01 02 D9 6B 3F
@0232                         T15/L4   Post compensation: 06 0F
@0236                         T07/L22  I2C-7: 70 FE 52 00 D2 01 52 01 02 00 82 01 02 00 2E 00 AE 01 2E 00 42 00 C2 01 42 00 66 00 E6 01 66 00
@0258                         T06/L3d 
@0259                                 T14/L6   Lowpass: 100Mhz
@025f                                 T46/L8   Type 46: 01 00 41 2B B0 BC
@0267                                 T46/L8   Type 46: 01 01 FF 03 6C 3F
@026f                                 T15/L4   Post compensation: 07 0F
@0273                                 T07/L22  I2C-7: 70 FE 52 00 D2 01 52 01 0A 00 8A 01 0A 00 2E 00 AE 01 2E 00 42 00 C2 01 42 00 66 00 E6 01 66 00
@0295                         T06/L3d 
@0296                                 T14/L6   Lowpass: 500Mhz
@029c                                 T46/L8   Type 46: 01 00 30 F2 B2 BC
@02a4                                 T46/L8   Type 46: 01 01 BA D9 6B 3F
@02ac                                 T15/L4   Post compensation: 08 0F
@02b0                                 T07/L22  I2C-7: 70 FE 52 00 D2 01 52 01 12 00 92 01 12 00 2E 00 AE 01 2E 00 42 00 C2 01 42 00 66 00 E6 01 66 00
@02d2 T1a/L6   Dynamic range +/-1.000V


Would you be able to eleborate a bit on how you were able to "tear down" the EEPROM data to this level? I'm currently attempting something similar with a TekVPI probe and some pointers would be greatly appreciated .

[dxl]

I've got all that information from looking at the tekscope software. I wrote a tool to read/write those files:

https://github.com/svenschnelle/tekprobe/tree/master

It produces a json file from a binary file and back. So you can edit the content as a json file, and generate the eeprom image. I did this because i want to use my P6339A probes with a MSO70404, which didn't work with
the original eeprom content. But i managed to generate a new eeprom file that works. This one doesn't work
with the old TDS794D, but who cares. ;-)