| Electronics > Repair |
| Agilent 34401A Bubble on PCB ... can it be saved ? (SOLVED) |
| << < (18/24) > >> |
| The_Spectrum.A_idiot:
the rest of the ranges measure same as before. okay. |
| The_Spectrum.A_idiot:
--- Quote from: Dr. Frank on September 24, 2024, 03:45:52 pm ---what about 1M and 100k ranges? Next step: Please remove Q203 and measure these 3 currents from pin 2 of Q202 to AGND / INPUT LO. Frank --- End quote --- Q203 removed and cleaned everything flux coated results :'( pin 2 of Q202 to INPUT LO 000. ohm range -997.6 μA 0.1k range - 997.6μA 00.1k range -99.38μA 000.1k range -9.89μA 0.1M range -4.92μΑ 00,1M range - 0.35μΑ ** 000,1Μ range -0,34μΑ ** Thank you in advance |
| Dr. Frank:
Ok, please re-insert CR202 and Q203. You might then test these currents on the outside (Input Lo / Hi) again. Have you tested the old components, Q203-Q210, Q211, Q202 and CR202 if and how they had been damaged? If these parts are all damaged there had been a very high overvoltage event, which could have affected U201-B, but also C210 and U101-E. So my next guess would be to remove or replace C210, that's a 0805 ceramic capacitor .. I don't know if it's a special type for low leakage currents.. It's a COG / NP0, which usually has better insulation than X7R. You might check this components outside for leakage, when applying 20V in series. Have you got a genuine, new AD706? Frank |
| The_Spectrum.A_idiot:
Q202 I was in between what component to select I was between : https://eu.mouser.com/ProductDetail/512-MMBFJ176 (this one is installed) and https://eu.mouser.com/ProductDetail/106-SMP5461 I will reinstall the rest and order the capacitor If U101 is broken I should assume that this is the end of this journey right ? Thank you in advance |
| The_Spectrum.A_idiot:
--- Quote from: Dr. Frank on September 24, 2024, 04:20:32 pm ---Ok, please re-insert CR202 and Q203. You might then test these currents on the outside (Input Lo / Hi) again. Have you tested the old components, Q203-Q210, Q211, Q202 and CR202 if and how they had been damaged? If these parts are all damaged there had been a very high overvoltage event, which could have affected U201-B, but also C210 and U101-E. So my next guess would be to remove or replace C210, that's a 0805 ceramic capacitor .. I don't know if it's a special type for low leakage currents.. It's a COG / NP0, which usually has better insulation than X7R. You might check this components outside for leakage, when applying 20V in series. Have you got a genuine, new AD706? Frank --- End quote --- I got this from mouser. https://eu.mouser.com/ProductDetail/584-AD706JRZ No ebay or unknown source components. |
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