Hi Gang,
I just picked up a Fluke 8840A from the auction place. I liked the 8842 tear-down Dave did, and that inspired me to pick this one up. I got lucky, because it is better then I expected it would be. I looked under the hood before I powered it up, and to my surprise found it had the AC option board installed. That was not listed in the auction, and it was not seen as a factory installed option on the back panel.
I wanted to look at the board for any obvious problems before juicing it up. It looked perfect. All the PS caps looked good, no sign of any previous repairs or modifications. The fuses were all the correct values, and were aok. No sign of any thermal problems were seen. It passed the sniff test. Leaving the cover off, I turned it on and the display sprang to life. Nice and bright, no dim segments. So far, so good.
I don't have any precision voltage or resistance sources, but I do have other multi-meters to check it against. I ran it through some AC and DC voltage checks, and some resistance measurements. Looks good. I checked to see if anything on the board was getting hot. Nope..cool as a cucumber. I did the self test based on the service manual, and all passed.
Now, the date codes on the chips tell me this was made in mid-1990. So, this puppy is 30 years old. It seems to have been treated well in a lab environment, and is cosmetically nice. A keeper! Ok, now I want to keep it happy for years to come. That brings me to the point of my post.
I want to replace the PS electrolytic caps, and the tantalum caps I hear everybody looks at suspiciously. I want to go with high quality replacements. Based on the schematic and parts callout in the service manual, this identifies the following:
Electrolytic s
--------------
C601, electrolytic 6800 uf, 16 volts
C603, electrolytic 330 uf, 100 volts
C605 & C607, electrolytic 470 uf, 50 volts > (SOLV PR) Not sure what that means?? It's in the call-out.
C611, electrolytic 100 uf, 50 volts
Tants
------
C204,602,608, C612, 1uf, 35 volts
That's what I see, 5 electrolytics and 4 tantalum's. I figure Nichicon for the electrolytics. I can search out Digikey or Mouser for them. I don't know what to use for the tantalums..? If anyone has done this before on a Fluke 8840A, and has part numbers to share..BY ALL MEANS, PLEASE DO. As it stands, there does not appear to be any issues at present, and I want to keep it that way. I can look at all the PS rails and measure voltages and ripple, but I would like to change them even if all looks good due to their age. I'm open to suggestion on what to use for the tants or the replacements in general!!
Thanks for reading, and any advice offered!
Mike