A rather nice 5-channel Hi-Fi amplifier with bouncing/intermittent power switch and mechanical problems.
Please click on the images to enlarge
Corrected factory mechanical design flaws, major overhaul
Transformers were too fat to fit between channels
Input terminal blocks inadequate
No secondary side connection to mains earth
Made power switch operate correctly
Power switch would bounce on and off when pressed.
Description of images:
Before the repair, the mains transformers were too fat to fit between the heatsinks on adjacent channels. This caused them to progressively 'lean' towards the right of the casework. They were only fixed to the casework from underneath and were beginning to work loose
Pre-repair mounting of the mains transformers using a bolt and dished washer. Because the channel was leaning, the capacitors (top-right) were contacting the base of the casework causing connection problems
Inadequate mains input terminals crimping solid core cable. The cable was beginning to work loose
Mains power circuit board incorporating our modification (small white board) to allow the power switch to reliably turn the amp on and off. Also contains a few minor modifications to increase the reliability of the amplifier. Note the replaced input terminal blocks to the right of the board
Disassembly of the amplifier channels in order to drill and tap the tops of the heatsinks and pot the transformers
Filling the transformer centres with potting resin to provide a new fixing. Getting rid of the dished washer saves a few millimetres per channel which was enough to allow them to sit straight within the casework
Post-repair mounting of the transformers without the dished washer
Additional mechanical bracing to prevent amplifier channels moving in the future. The channels now sit solid and straight