comparison: content/HPZR24W.rst
content/HPZR24W.rst
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| 126:521c35556177 | 128:aba381b2bac9 |
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| 28 - a main controller board, | 28 - a main controller board, |
| 29 - an LCD driver board, and the monitor being a bit old, | 29 - an LCD driver board, and the monitor being a bit old, |
| 30 - a blacklight HV driver board. | 30 - a blacklight HV driver board. |
| 31 | 31 |
| 32 | 32 |
| 33 .. image:: {static}images/ZR24W/back.jpg | 33 .. image:: {static}/images/ZR24W/back.jpg |
| 34 :alt: Back of the HP ZR24W | 34 :alt: Back of the HP ZR24W |
| 35 | 35 |
| 36 First thing, to make sure the problem comes from the PSU, I powered the monitor | 36 First thing, to make sure the problem comes from the PSU, I powered the monitor |
| 37 from my bench power supplies. I used one output of my HP E3648A to generate the | 37 from my bench power supplies. I used one output of my HP E3648A to generate the |
| 38 19V rail that powers the backlight. It was a bit short (CC limited at 16V), but | 38 19V rail that powers the backlight. It was a bit short (CC limited at 16V), but |
| 39 enough to power the backlight. The second output was used to produce the 12V, | 39 enough to power the backlight. The second output was used to produce the 12V, |
| 40 and the 5V was generated by my very old home made PSU. | 40 and the 5V was generated by my very old home made PSU. |
| 41 | 41 |
| 42 .. image:: {static}images/ZR24W/ext_power.jpg | 42 .. image:: {static}/images/ZR24W/ext_power.jpg |
| 43 :alt: Testing the display with my bench PSU. | 43 :alt: Testing the display with my bench PSU. |
| 44 | 44 |
| 45 The monitor was working fine when powered from these PSUs, so the problem was, | 45 The monitor was working fine when powered from these PSUs, so the problem was, |
| 46 indeed, this Tatung PWB-1336-02 switching PSU: | 46 indeed, this Tatung PWB-1336-02 switching PSU: |
| 47 | 47 |
| 48 .. image:: {static}images/ZR24W/psu_top.jpg | 48 .. image:: {static}/images/ZR24W/psu_top.jpg |
| 49 :alt: Top of the Tatung PWB-1336-02 PSU | 49 :alt: Top of the Tatung PWB-1336-02 PSU |
| 50 | 50 |
| 51 .. image:: {static}images/ZR24W/psu_bottom.jpg | 51 .. image:: {static}/images/ZR24W/psu_bottom.jpg |
| 52 :alt: Bottom view of the Tatung PWB-1336-02 PSU | 52 :alt: Bottom view of the Tatung PWB-1336-02 PSU |
| 53 | 53 |
| 54 The design is nice and clean. Electrolytic caps however are not the best ones | 54 The design is nice and clean. Electrolytic caps however are not the best ones |
| 55 (mostly Lelong ones I think), which is not really a surprise in this kind of | 55 (mostly Lelong ones I think), which is not really a surprise in this kind of |
| 56 device. | 56 device. |
| 83 marked as "On/Off" and "Vadj"). But these are directly routed to the backlight | 83 marked as "On/Off" and "Vadj"). But these are directly routed to the backlight |
| 84 board and take no part in the PSU management. | 84 board and take no part in the PSU management. |
| 85 | 85 |
| 86 | 86 |
| 87 My first test has been to plug my cheap `electronic load | 87 My first test has been to plug my cheap `electronic load |
| 88 <{static}/ZPB30A1.rst>`_ on the 5V with the 2 other voltages stopped. | 88 <{filename}/ZPB30A1.rst>`_ on the 5V with the 2 other voltages stopped. |
| 89 | 89 |
| 90 And I could reliably sink 3A from there. So the problem must be on one of the 2 | 90 And I could reliably sink 3A from there. So the problem must be on one of the 2 |
| 91 other rails. | 91 other rails. |
| 92 | 92 |
| 93 But I also could sink the max amperage from the 2 other power rails (1A from | 93 But I also could sink the max amperage from the 2 other power rails (1A from |
| 102 PSU being "hot" (around 400V), and having no isolation transformer, I could not | 102 PSU being "hot" (around 400V), and having no isolation transformer, I could not |
| 103 probe the signals correctly (using 2 probe and displaying the A-B curve, which | 103 probe the signals correctly (using 2 probe and displaying the A-B curve, which |
| 104 is some kind of a joke on the Rigol, since you cannot hide the A and B curves: | 104 is some kind of a joke on the Rigol, since you cannot hide the A and B curves: |
| 105 the curve substraction is purely computed from displayed curve. When I found | 105 the curve substraction is purely computed from displayed curve. When I found |
| 106 how useless this was on the Rigol, I had not enough energy to extract my old | 106 how useless this was on the Rigol, I had not enough energy to extract my old |
| 107 `Tek 2445A <{static}/TeK2445.rst>`_ from under the pile of test equipment | 107 `Tek 2445A <{filename}/TeK2445.rst>`_ from under the pile of test equipment |
| 108 stowed in the closet...) | 108 stowed in the closet...) |
| 109 | 109 |
| 110 | 110 |
| 111 A glimpse at schematics | 111 A glimpse at schematics |
| 112 ----------------------- | 112 ----------------------- |
| 144 transformer managed by the TNY279 is not enough to start the CM6807. | 144 transformer managed by the TNY279 is not enough to start the CM6807. |
| 145 | 145 |
| 146 | 146 |
| 147 The application circuits are as follow: | 147 The application circuits are as follow: |
| 148 | 148 |
| 149 .. image:: {static}images/ZR24W/tny279_app_circuit.svg | 149 .. image:: {static}/images/ZR24W/tny279_app_circuit.svg |
| 150 :alt: Example application circuit for the TNY279PN controller (from the `datasheet <TNY279PN>`_) | 150 :alt: Example application circuit for the TNY279PN controller (from the `datasheet <TNY279PN>`_) |
| 151 | 151 |
| 152 .. image:: {static}images/ZR24W/CM6807_app_circuit.svg | 152 .. image:: {static}/images/ZR24W/CM6807_app_circuit.svg |
| 153 :alt: Example application circuit for the CM6807 controller (from the `datasheet <CM6807>`_) | 153 :alt: Example application circuit for the CM6807 controller (from the `datasheet <CM6807>`_) |
| 154 | 154 |
| 155 In this PSU, the input DC of the TNY279 (the point just before R5 in the app | 155 In this PSU, the input DC of the TNY279 (the point just before R5 in the app |
| 156 circuit) in connected just behind the PFC circuit, i.e. just after the D2 diode | 156 circuit) in connected just behind the PFC circuit, i.e. just after the D2 diode |
| 157 of the CM6807 app circuit. | 157 of the CM6807 app circuit. |
| 158 | 158 |
| 159 In order for the PSU to generate the 5V rails even when the CM6807 is off, | 159 In order for the PSU to generate the 5V rails even when the CM6807 is off, |
| 160 there is derivated DC input path, from the bridge rectifier to the input DC | 160 there is derivated DC input path, from the bridge rectifier to the input DC |
| 161 rail, consisting in a diode (D922 on the PCB) followed by a thermistor (R915): | 161 rail, consisting in a diode (D922 on the PCB) followed by a thermistor (R915): |
| 162 | 162 |
| 163 .. image:: {static}images/ZR24W/input_DC.jpeg | 163 .. image:: {static}/images/ZR24W/input_DC.jpeg |
| 164 :alt: Input DC showing both paths (yellow: via the PFC, red: the alternate | 164 :alt: Input DC showing both paths (yellow: via the PFC, red: the alternate |
| 165 path when power saving is on). | 165 path when power saving is on). |
| 166 | 166 |
| 167 | 167 |
| 168 Finally, the culprit | 168 Finally, the culprit |
