| Electronics > Repair |
| DSO-X 3024A Power Supply defect |
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| asp:
Hi Does anyone know the value for the resistor in the picture below? Mine has a hole in it and it's open. The resistor in question is located on the daughter board near the UC3842 PWM controller of the PSU Thanks Update: The resistor is a 499Ohm, and if that is gone the comparator might be gone as well |
| NY2KW:
Thanks to all for the detailed repair advice. My 3054A suddenly died but on inspection I saw no obvious blown parts, but the PCB near the 4 22k resistors was badly discolored, no obvious cracks. The fuse was still good but the pair of IF840's were both reading as dead shorts in both directions. I had a PQC250-12 from another project so quickly made the new harness's and used a Teflon sheet as an insulator between the harness and the new SMPS. Turned on and works perfectly. The power button is reversed as the PQC250 datasheet says that its J2 Pin 4 (PS-ON) which goes to the scope's Molex Pin 9 has to be pulled low to power on while the original CCH125 series its J6 Pin 6 to the scopes Molex Pin 9 has to be pulled High to power on. I am not a purist but I need the PQC250 for my original project so instead of buying another Murata, it seems the button logic on the Mean Well RPSG-160-12 should work same as original, so that's where I'm going next. Too bad this means making a new harness. Jerry NY2KW |
| jtmp:
I have had the same blown power supply on a DSO-X 2012A, and replaced with a Mean Well RPS-400-12 following the advice above. However now I am getting a ~120mVp-p ripple @~4kHz on the scope trace, even with the probe shorted to ground. Have I done something wrong here, or are these power supplies much noisier than the original? I don't remember what I used to get but surely it wasn't this bad?! Cheers |
| EE-digger:
Old thread but still highly relevant. I finally had time to open my (10/2016) build DSOX3104T and was surprised to find the same troubled (??) supply, same revision, but with the GE branding. So my question for all. Did these supplies happen to come to this thread to die? :-BROKE Perhaps units that smoked, exploded or otherwise died had enough run time and heat to bring out the problems. With the nature of the problems, I would expect a high failure rate unless improvements were made without revision change. This problem, NAND corruption AND NAND LIFE IN GENERAL have me worried. If Daniel drops by, I would love to hear the Keysight take on these issues. |
| electr_peter:
PSU seems to be fragile, at least in older DSOX2/3 models. Scope is newer fully off (ON/OFF switch is actually soft power-on) and 6W heat in standby has to go somewhere. One strategy to prolong PSU life is to disconnected mains externally when not in use. NAND issues seems to have been mitigated (at least partially) via FW updates. |
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