I purchased and built the K8020 valve control amplifier and works very well but has developed a strange fault.
After playing say 3 CD tracks the right channel drops out.when reset and switched back on there is a delay of approx. 30 seconds when it comes back on both channels working. After say another 3 tracks the problem repeats.We discussed the possibility there was maybe a problem with the PIC controller IC as I can’t think of any other component which could display such an intermittent timed fault.
I would be extremely grateful for any feedback advice on the likely solution.
Both channels are driven by the same PIC output, so we do not suspect the PIC.
Strange problem. Check if it is a thermal problem, related to the valve, relay, soldering, etc…
I have replaced both valves,swapped relays RY6 RY7 with both RY5
relays on monitor inputs which I dont require,and I have also replaced T06.T07 D06and D07 all to no avail as the problem still exists —totally stumped any suggestions?
I purchased a set of capacitors from Maplin and replaced all of those associated with the right channel line out circuit C06 C16 C19 C22 C33 AND C34.EUREKA! Problem solved both channels working may have been a thermal problem as you suggested.Now with K8020
hooked up to K4040 I built earlier – Hi Fi heaven