Mk 106 metronome

mk 106 metronome
led does not light and constant fast tone unable to adjust speed could not
make it slower ,checked transistor bc517

Make sure you did not swap the trimmers.

mk 106 metronome
I also have a problem - unit appears to work but LED pulses rather than flashes - it is very quiet (unusable) even on full volume when the LED dims to very dim. I’ve checked and double checked assembly and examined all solder joints with a lens - all seems OK - any suggestions?

Make sure the trimmers are not swapped.
Check speaker, it is very sensitive to overheating.

mk 106 metronome

Many thanks for your suggestions.
Speaker works fine from different source and the trimmers are definitely not swopped - 100ohm Vol - 1M beats/min.
Anything else I can try? :?

My metronome worked fine when first assembled, but when I mounted it in a plastic kit case it stopped altogether…now the LED stays brightly illuminated…ie no blinking but no sound at all.

Thought I may have damaged the rather delicate speaker so disconnected and added a similar one but no different. Any suggestions would be appreciated.

Very likely a mechanical problem due to the manipulations you’ve performed while building in the unit.
Check for interrupted PCB track, loose PCB pads, loose solderings, bent or broken components, bad contacts etc…

At its loudest the LED stays off otherwise the LED stays on except a barely perceptible flicker when the click sounds. It’s not very loud at all.

Darlington transistors are made from pure evil so I will try some different ones when I have time and hopefully stop back and report my findings.

The metronome works when first switched on but T1 and R6 overheat. Gradually the LED does not mirror the beats, and goes dim. Any suggestions. The trimmers are installed correctly. Also, as above, “…at its loudest the LED stays off otherwise the LED stays on except a barely perceptible flicker when the click sounds. It’s not very loud at all…” once it overheats.

I finally got around to it and the first transistor I tried (BC183) works a treat. I wonder what the reason was to have a hi gain transistor included in the kit?