Hi
I thought I would pass on a recent experience as it's been a bit quiet on here lately. Not that I do so out of any sense of personal triumphalism (well, just a bit - nice to know the old man is not completely past it), but maybe of some help to others.
Briefly my setup is, LP12, Uphorik, Magic Preamp, 2200 power amp (Dynamik), CD and Pekin tuner. For recent months I had concluded that my system sounded "sour". High frequencies were unpleasant, and some bass seemed to be missing on all sources. I began to feel that my hifi days might be drawing to an end, blaming my hearing or unreasonable expectations of a system.
A week ago I had been playing some LPs and the system was still on, although no record was playing. I put my hand behind my hifi rack to straighten one of the mains cable. I heard a significant crackle coming from both speakers. I spent some time switching things on and off and plugging cables in and out in a logical sequence.
I tracked the problem down to the power input socket of the 2200. It seemed a bit loose. Presumably I could only hear the crackle when I waggled this when the Uphorik was selected by the preamplifier because of its great sensitivity (configured for moving coil). Having once been an electrical engineer and not being one to fear going where angels wouldn't, I removed the 2200 from the rack and slid off the outer case.
The mains input socket and associated circuitry is within the Dynamik power supply, so I had to remove the cover to this. (Two of the screws are a bit inaccessible and should only be removed if you have either a magnetic screwdriver, some soap, some beeswax or a captive screwdriver).
I looked at the Dynamik board and admired its complexity - how all that power could come through a couple of cotton reels, some small capacitors and a scale model of Manhattan island. I had suspected that the joint between the circuit board and the mains socket had fractured: this was not the case. Then I noticed a small screw to chassis near to the mains socket which was marked "earthing point". I waggled the mains socket. The board flexed and could move up and down by a couple of millimeters. The screw was loose and was obviously failing to earth the power supply board properly.
Within ten minutes the screw had been tightened, the amplifier reassembled, and music was emanating once again from my system. I still struggle a bit with tunedem comparisons, but this improvement would have been noticeable over the telephone. An easy repair equivalent to a major upgrade. Funny how little things can affect our hifis.
I suppose it goes without saying - do not pull your amplifier to pieces if you are not electronically qualified and you will invalidate the guarantee.
Don, overcast and windy downtown York
Simple repair to 2200 power amplifier
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