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content/TeK2445.rst
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| 1 ================================== | |
| 2 Tektronics 2445 scope PSU repair | |
| 3 ================================== | |
| 4 | |
| 5 :Author: David Douard | |
| 6 :Date: 2016-03-06 | |
| 7 :Category: Electronics | |
| 8 :Tags: Tektronics, 2445, analog scope, repair, test equipment | |
| 9 | |
| 10 I've recently took my good old Tek 2445 scope from the cellar | |
| 11 (along with my {tag}HP8904A signal generator), and it showed signs of | |
| 12 tired PSU: unstable display, noise, then the typical noise of a | |
| 13 capacitor failure. | |
| 14 | |
| 15 Here is the beast: | |
| 16 | |
| 17 .. image:: {filename}images/tek2445/tek2445.jpg | |
| 18 :alt: My old Tektronics 2445 scope | |
| 19 | |
| 20 And some pictures of its womb: | |
| 21 | |
| 22 .. image:: {filename}images/tek2445/tek2445_A1.jpg | |
| 23 :alt: The main analog board. | |
| 24 | |
| 25 .. image:: {filename}images/tek2445/tek2445_top.jpg | |
| 26 :alt: Top view of the scope. | |
| 27 | |
| 28 The PSU consists in two PCBs coupled with long jumpers. It's not very | |
| 29 difficult to disassemble them but not that straighforard either. I've | |
| 30 seen easier test equipments to take apart. | |
| 31 | |
| 32 Whatever, its problem was a classic failure of several X2 and Y | |
| 33 capacitors on the regulator board (A2): | |
| 34 | |
| 35 .. image:: {filename}images/tek2445/PSU_A2.png | |
| 36 :alt: The regulator board os the PSU. | |
| 37 | |
| 38 .. image:: {filename}images/tek2445/board_a2.jpg | |
| 39 :alt: The regulator board os the PSU. | |
| 40 | |
| 41 .. image:: {filename}images/tek2445/board_a2_C1018.jpg | |
| 42 :alt: Dead C1018 capacitor. | |
| 43 | |
| 44 | |
| 45 and the inverter board (A3), mainly C1020, C1051 and C1052: | |
| 46 | |
| 47 .. image:: {filename}images/tek2445/PSU_A3.png | |
| 48 :alt: The inverter board of the PSU. | |
| 49 | |
| 50 | |
| 51 For now, I've replaced them with parts from old switching power | |
| 52 supplies (from old Dell and IBM computers), but I'd rather replace | |
| 53 them with brand new components. I also still have some small display | |
| 54 instabilities, which I need to investigate a bit more. I'll probably | |
| 55 replace most of the electrolytics caps on the PSU so that I won't have | |
| 56 to repair again any time soon (famous last words). | |
| 57 | |
| 58 |
