6 to 8 years ago a K4700 set is installed during a revision of my vintage quad405-1 amplifier.
The k4700 kit is mounted on the inside of the metal top cover of the Quad and installed by professionals (DADA Electronics in Antwerp). The cabling looks solid.
For some time now the left channel drops out suddenly, mostly after some hours playing but, most frustrating, it also happens that the Quad plays perfect for the whole day.
The Quad has been tested for this problem and they said the machine runs perfect and nothing was found. I assume they removed the cover were the Velleman has been glued on during the test.
When I remove the cover the left channel mostly starts playing and the quad runs as it should be. otherwise a tiny tick on top of the Quad and the channel starts playing also.
Yesterday when the channel drops out I tilted the Quad 90 degrees over while playing and it suddenly it starts playing again. when I tilted it back it stops on the left channel again.
I assume that it perhaps can be the Velleman switches who gives the problem.
The things what I see and has checked.
- Before the channel drops out the sound becomes poorer for some seconds.
- The yellow led does its work and goes out after 6 seconds, but the red led then burns minimal, like a empty battery bulb.
- When the problem occurs, the cooling ribs of the left channel are getting colder.
- When I put the power off, mostly I hear a loud tick from the speakers.
- When the problem occurs the inside of the Quad is warm.
What can I do to fix this.