| Electronics > Repair |
| HP 53310A - Power supply troubles |
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| TAMHAN:
Hello Folks, my trust old MDO recently went puber on me - clearly a trouble in the switching mode PSU. As I needed the unit somewhat urgently and my father loves tinkering just as much as I do, we decided to bury grudges for now and get to work. Our MDO had the PSU from Computer Products, who AFAIK bought up Boschert. Now, our problem is this. We managed to remove 17 caps which we considered suspect (the ERSA Nano was a bit to weak for it in fact), and found SIGNIFICANT electrolytic leakage under the two 2200uf caps and also the two groups of two 1000yF/35vF standing glued together to some other components with white silicone rubber. Now, our problem is. The board is halfpopulated. How would you suggest to proceed cleaning, as not to damage the other components on the board? Or would you simply solder in new capacitors of higher quality? |
| TAMHAN:
And, as someone else might need it, here is our parts list for the 17 caps we killed so far. All of the Elcos are RADIAL, so two pins on one side. No need to buy the expensive ones which look like ------|CCCCCCCC|--------- C26, 27 and 49 6800yF / 6v3 (no typo) C40, C41 2200yF / 35V, one showed massive leakage C7,8,9,10,11,12,13,14 were 1000yF/30V C15, C16, C30, C31 also, but they showed massive leakage |
| TAMHAN:
And finally, a pic of the goo so that you can maybe advise us on how to proceed re the repair. Also, forgive the stupid question. Am I right in the assumption that the cable binders and the white silicone rubber glue are intended for suppressing oscillations? |
| wn1fju:
The last one of these I fixed was cleaned simply by repeated hits of alcohol with a toothbrush. You definitely should try to get the gunk off, not just solder in new caps. Also, search the forums as there have been a few discussions about this power supply as it relates both to the 53310A and to many of the HP oscilloscopes that it was also used in. |
| TAMHAN:
Hello, and, to report success. Recapped it, and it works nicely again. Cleaning was done on a best effort basis, aka only where I could really see the electrolyte, with IPA and cotton swabs. My father and I kept notes, if anyone ever needs them: Caps used: Hitano Low-ESR (the green ones) for all values except 220yF Caps replaced C35, C39, C34 - 220yF 50V C32, C33 1000yF 35V C50 220yF 50V C42 2200yF 50V and the ones listed above, ofc. The print of the PCB is very solid, we did not have any damaged traces as of yet. But we acted swiftly: after the MDO broke down, we ran it for less than 1h. So far, we did not bother to replace the cable ties or the silicone glue. And the PSU still works flawlessly...no whining to notice either. |
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