| Electronics > Repair |
| HP/Agilent Infinium 548xx scope - Power Supply Schematic ! |
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| 999masks:
thanks for the post. Really appreciate your work i jnow it is very time consuming. I have a question if you guys can give me any suggestions i will appreciate it. I have Agilent infinum 54855DSO which i accidentally shorted the ATx connector i belive 12V output. after that the oscilloscope stopped powering on. Mine has Celestica 5100 power supply with 4 power modules. The current issue if i remove the connector from power supply that goes to analog power generation board and plug the power cord, it will power on and boot. At this state I measured all the voltages from power supply which are good. As soon as i connect that plug (this is not a power cable) it wont turn on. I measured the voltages from those wires, basically the power supply has 4 different power modules. 2x3.3V 1x5V and-12 , 0, 12V the connector that i was referring, carries the same voltages as their output at ATX connector (maybe POWER GOOD signal?) basically from that plug if i remove the pin that connects to -12,0 +12v =24v (any side) the oscilloscope will power on and boots. At this state the neither power button or any button works on the front panel. I am asking if you can help me to troubleshoot or provide the model schematic or similar. thanks in advance |
| microbug:
--- Quote from: 999masks on February 20, 2024, 04:56:11 am ---thanks for the post. Really appreciate your work i jnow it is very time consuming. I have a question if you guys can give me any suggestions i will appreciate it. I have Agilent infinum 54855DSO which i accidentally shorted the ATx connector i belive 12V output. [...] --- End quote --- This really belongs in a new thread. I am really impressed by the clarity and beauty of the schematic in the original post. If only major CAD companies cared as much about such things. |
| ARF:
It's good that I found this article. Thanks for the diagram. I decided to make a complete re-cap of the power supply of my 54845A. There is no point in waiting for problems and I decided make it in advance. The 470uf/450V capacitor has the specific contacts with 22.5mm step. I was not able to buy such a new brand capacitor, but I was able to buy a 680/400V. I was sure that this power supply does not have a PFC, but in the diagram I see that it is there and there will be 380V on this capacitor. I'm wondering how safe it is to use a 400V capacitor. |
| Conventional Wisdom:
I understand your dilemma. The original cap was discontinued some time ago, and I couldn't find a drop-in replacement, either. While it is common to choose an electrolytic with a voltage rating higher than the expected voltage, presumably to reduce stress and maximize life, I'd feel OK about the 400 V cap here, because: 1) The 380 V is pretty well regulated and unlikely to rise above 400 V for an extended time, and 2) Although manufacturers generally no longer specify surge voltages the way they used to be (I remember when both WVDC and SURGE were printed right on the capacitor case), I have to expect that there's still a reasonable margin over the working voltage. IMHO in this PFC circuit it's more important that the replacement cap's high-frequency ripple current rating be at least as high as the original's. I welcome others' comments. Good luck - CW |
| GGMM:
hello, simple question. I’ll get an HP 54810A that probably has power out. It clicks and that’s it. I wanted to know if we can simply test the power supply empty (connector disconnected) or it is imperative to have a charge or other for it to work. Of course before doing anything, I will do the inspection of the power supply (capacitor, welds, etc.) Is there a known component that often drops? the classic failure actually cdt |
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