Digest for sci.electronics.repair@googlegroups.com - 1 update in 1 topic

"Peter W." <peterwieck33@gmail.com>: Dec 28 08:17AM -0800

Follow up from 2.5 years ago. Over the last few days, I did my annual-re-making-of-all-connections exercise on the HK system (Citation 17/18/19, AR M5 speakers, Revox turntable, Revox cassette player, Sony CD Changer, ). Four things arose:
a) The phono-input (17) was fuzzy. Fix was re-solder the right-channel ground on the input jack - HK components of that era are notorious for cold-solders. Luckily it was visible.
b) Minimal hum, both channels, only when the 17 was ON. Cleaned up two internal grounds, went away.
c) The *other* channel became intermittent - but full output from the 17, so, within the 19. Much longer fix - with the wooden stick method, literally poking around. Found the 4-section Molex connector (only two sections connected) was intermittent at the ground. NOT the connector, but the square pin through the driver board was cold-soldered and/or had cracked at the board. Interesting inasmuch as it tested for continuity, but was intermittent in operation Re-soldered - good now. I also re-soldered all the pins on the other Molex connectors - figuring they were all done at the same time, likely by the same individual with the same equipment.
d) The AR woofers both needed new surrounds. Which by pure blind luck, I had sitting around with the proper glue. Took about 4 hours each - mostly as that is how long it takes the glue to set. Better now!
 
 
While I was there, I adjusted the muting threshold and stereo thresholds for the 18. The target stations have reduced power slightly, making the adjustment more of a convenience than a necessity.
 
Anyway, no more troubles. Next: the main system.
 
Peter Wieck
Melrose Park, PA
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