Teardown : Tektronix TCA-1MEG high-impedance amplifier for TekConnect - Page 1
Forum section: electronics / testgear

author: TiN
author_rank: Super Contributor
timestamp: July 04, 2015, 07:20:18 pm
content: 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):

author: MSS
author_rank: Newbie
timestamp: March 16, 2020, 07:37:50 pm
content: 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?

author: David Hess
author_rank: Super Contributor
timestamp: March 17, 2020, 08:51:13 pm
content: 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.

author: charlyd
author_rank: Frequent Contributor
timestamp: May 05, 2021, 05:59:21 pm
content: i bought this TCA-1MEG adapter and after connectingit gives "fail". does any have experience with these failedadapters ? 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 backhelp or donor unit wantedi will open up new post.https://www.eevblog.com/forum/testgear/tektronix-tca-1meg/msg3801434/#msg3801434

author: dxl
author_rank: Regular Contributor
timestamp: July 14, 2022, 04:00:25 pm
content: Quote from: TiN on July 04, 2015, 07:20:18 pmAnd here's the eeprom content "teardown"Code:@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

author: ddrl46
author_rank: Regular Contributor
timestamp: August 12, 2022, 06:22:46 pm
content: Quote from: dxl on July 14, 2022, 04:00:25 pmWould 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.

author: dxl
author_rank: Regular Contributor
timestamp: August 12, 2022, 06:47:00 pm
content: 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/masterIt 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 withthe original eeprom content. But i managed to generate a new eeprom file that works. This one doesn't workwith the old TDS794D, but who cares. ;-)