content/TeK2445.rst

Tue, 15 Mar 2016 16:23:22 +0100

author
David Douard <david.douard@logilab.fr>
date
Tue, 15 Mar 2016 16:23:22 +0100
changeset 38
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parent 29
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child 44
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permissions
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[10MHz] typos

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1 ==================================
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2 Tektronics 2445 scope PSU repair
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3 ==================================
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4
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5 :Author: David Douard
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6 :Date: 2016-03-06
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7 :Category: Electronics
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8 :Tags: Tektronics, 2445, analog scope, repair, test equipment
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9
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10 I've recently took my good old Tek 2445 scope from the cellar
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11 (along with my {tag}HP8904A signal generator), and it showed signs of
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12 tired PSU: unstable display, noise, then the typical noise of a
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13 capacitor failure.
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14
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15 Here is the beast:
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16
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17 .. image:: {filename}images/tek2445/tek2445.jpg
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18 :alt: My old Tektronics 2445 scope
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19
2638f5cf375c [2445] publish the 2445 PSU repair (part 1)
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20 And some pictures of its womb:
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21
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22 .. image:: {filename}images/tek2445/tek2445_A1.jpg
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23 :alt: The main analog board.
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24
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25 .. image:: {filename}images/tek2445/tek2445_top.jpg
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26 :alt: Top view of the scope.
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27
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28 The PSU consists in two PCBs coupled with long jumpers. It's not very
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29 difficult to disassemble them but not that straighforard either. I've
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30 seen easier test equipments to take apart.
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31
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32 Whatever, its problem was a classic failure of several X2 and Y
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33 capacitors on the regulator board (A2):
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34
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35 .. image:: {filename}images/tek2445/PSU_A2.png
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36 :alt: The regulator board os the PSU.
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37
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38 .. image:: {filename}images/tek2445/board_a2.jpg
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39 :alt: The regulator board os the PSU.
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40
2638f5cf375c [2445] publish the 2445 PSU repair (part 1)
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41 .. image:: {filename}images/tek2445/board_a2_C1018.jpg
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42 :alt: Dead C1018 capacitor.
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43
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44
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45 and the inverter board (A3), mainly C1020, C1051 and C1052:
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46
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47 .. image:: {filename}images/tek2445/PSU_A3.png
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48 :alt: The inverter board of the PSU.
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51 For now, I've replaced them with parts from old switching power
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David Douard <david.douard@logilab.fr>
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52 supplies (from old Dell and IBM computers), but I'd rather replace
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53 them with brand new components. I also still have some small display
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54 instabilities, which I need to investigate a bit more. I'll probably
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55 replace most of the electrolytics caps on the PSU so that I won't have
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56 to repair again any time soon (famous last words).
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