content/TeK2445.rst

Tue, 28 Aug 2018 15:05:01 +0200

author
David Douard <david.douard@logilab.fr>
date
Tue, 28 Aug 2018 15:05:01 +0200
changeset 104
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parent 45
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child 115
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permissions
-rw-r--r--

improve hgignore

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3eed12f6592b [tek] part 2 of the PSU repair
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1 ==========================================
3eed12f6592b [tek] part 2 of the PSU repair
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2 Tektronics 2445 scope PSU repair: part 1
3eed12f6592b [tek] part 2 of the PSU repair
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3 ==========================================
29
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5 :Author: David Douard
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6 :Category: Electronics
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7 :Tags: Tektronics, 2445, analog scope, repair, test equipment
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3eed12f6592b [tek] part 2 of the PSU repair
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8 :series: Tek2445 PSU repair
3eed12f6592b [tek] part 2 of the PSU repair
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9 :series_index: 1
29
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11 I've recently took my good old Tek 2445 scope from the cellar
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12 (along with my {tag}HP8904A signal generator), and it showed signs of
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13 tired PSU: unstable display, noise, then the typical noise of a
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14 capacitor failure.
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16 Here is the beast:
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18 .. image:: {filename}images/tek2445/tek2445.jpg
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19 :alt: My old Tektronics 2445 scope
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20
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21 And some pictures of its womb:
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22
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23 .. image:: {filename}images/tek2445/tek2445_A1.jpg
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24 :alt: The main analog board.
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25
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26 .. image:: {filename}images/tek2445/tek2445_top.jpg
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27 :alt: Top view of the scope.
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28
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29 The PSU consists in two PCBs coupled with long jumpers. It's not very
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30 difficult to disassemble them but not that straighforard either. I've
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31 seen easier test equipments to take apart.
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33 Whatever, its problem was a classic failure of several X2 and Y
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34 capacitors on the regulator board (A2):
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35
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36 .. image:: {filename}images/tek2445/PSU_A2.png
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37 :alt: The regulator board os the PSU.
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39 .. image:: {filename}images/tek2445/board_a2.jpg
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40 :alt: The regulator board os the PSU.
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41
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42 .. image:: {filename}images/tek2445/board_a2_C1018.jpg
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43 :alt: Dead C1018 capacitor.
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46 and the inverter board (A3), mainly C1020, C1051 and C1052:
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47
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48 .. image:: {filename}images/tek2445/PSU_A3.png
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49 :alt: The inverter board of the PSU.
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52 For now, I've replaced them with parts from old switching power
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53 supplies (from old Dell and IBM computers), but I'd rather replace
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54 them with brand new components. I also still have some small display
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55 instabilities, which I need to investigate a bit more. I'll probably
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56 replace most of the electrolytics caps on the PSU so that I won't have
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57 to repair again any time soon (famous last words).
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