| Electronics > Repair |
| Keithley 2002 repair help |
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| nikonoid:
Yes, Guys, I used TiN articles a lot. This saga is slowly coming to the end. After cleaning with DI water, IPA and doing some fine baking, I gave meter a day to rest and cool. Testing today showed that almost surprisingly OHMS function is working now. :-DD It reads about 100pm high on a cold start, but then in just 5 minutes gets to good readings. At the same time AMPS results got a bit worse after this round of cleaning, but not much. After 30 minutes warm up the meter is pretty usable, considering it is running without top shield, metal case, etc. So now I am pretty confident that everything that had to be fixed is fixed. CONTAMINATION is the major problem that is left! This meter was missing case and top shield when I got it and was literally full and dust, insects and mice litter. The fact I could get it to this point is somewhat unbelievable. What else can I do to clean contamination, short of removing all the components? Thanks. |
| Kleinstein:
Congratulations :-+ If cleaning worked so far, it might be worth a second round. Dissolving contaminations is sometimes slow. So it might take quite some time and DI to get rid of some stuff. One could try a rather dilute acid - it can help with some salts / deposits. With now not much lower leakage, there should not be very much dirt left - so maybe just a few more steps of dilution. |
| Zucca:
My .02$: Soak it in a bath of 50% distilled H2O and 50% IPA... leave it there for a day or two... then rinse it with fresh distilled water and finally in oven again. repeat if necessary. Maybe an antistatic brush could help. |
| nikonoid:
I have done special oil free air dusting and anti-static brush before using liquids. I wanted to minimize dirt flowing under microchips. As the bath is concerned, could some elements be damaged by it? Like mechanical relays, voltage reference, large capacitors and maybe others. Is shallow bath, right to the top surface of pcb, a good option? Sent from my iPhone using Tapatalk |
| Kleinstein:
Relays could have a problem when the full board is in a bath. It depends on the types - some are washable, some are not. Especially reed type relays could be a problem due to increased leakage if the glass gets contaminated. The caps should not be a problem. The tricky part could be leakage under chips or relays. There can also be residue moved from the dirty power supply part towards the more sensitive parts (Ohms and volts input). So I would prefer more local cleaning. One could use the liquid locally, like a few drops or small spill, so it would only effect the area of interest. Local washing would be adding a few ml of water and remove it with a syringe or similar. So more like a shallow local bath, that is repeated several times. For the parts between chips the brush could also be good option for an initial cleaning. One can hardly avoid the part below the chips to get wet. Compressed air to blow the liquid out can be tricky, as some will end up as small droplets in other areas. It might still be the best option. The idea is usually to use enough water to dilute the dirt so much that there will be very little left. IPA or similar is than to a large part to dilute the residual water and allow better drying. |
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