broadz Posted January 27, 2021 Posted January 27, 2021 (edited) Hey guys, I’ve bought this and was curious as to the condition of the caps so I removed the cover for a couple of photos. Looks like it might need a re-cap and decent clean. Edited January 27, 2021 by broadz
Cafad Posted January 27, 2021 Posted January 27, 2021 A blast of compressed air will clean out most of that dust and fluff. The caps look OK though.
rockeater Posted January 28, 2021 Posted January 28, 2021 4 hours ago, Cafad said: A blast of compressed air will clean out most of that dust and fluff. The caps look OK though. That is exactly right. The caps there are made by Nichicon and Nippon Chemi-Con and appear to be OK.
broadz Posted March 26, 2021 Author Posted March 26, 2021 Turns out my suspicions were correct. It was not only dirty, there was evidence of leaking caps, sticky melted glue and a number of places on the board where the tracks had corroded. It would power up but make a constant scratchy and distorted sound with crosstalk across each of the inputs. A full strip down was performed and a number of components replaced, some with more audiophile-grade versions. Damaged tracks repaired and reassembled. A new volume pot has been ordered and will be replaced at the first sign of the common rotary pot failure every 840a goes through. Thanks very much to my audiophile friend who is very competent in high end amplifier repairs. Not completely sure how it is meant to sound but the final result sounds terrific! 1
pete_mac Posted March 26, 2021 Posted March 26, 2021 Well done and good job! It looks like plenty of glue which has gone off and corroded several components, as opposed to leaking caps. None of that brown gunk is from the capacitors themselves. Electrolytic caps do not contain a liquid as such - there is an electrolyte paste inside and it is not prone to leaking or oozing in the typical sense, and capacitors absolutely do not leak or ooze anything brown. 2
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