Help please with Volvo tacho/hour meter - stopped working

[Venus1]

Hoping someone has had this happen and can advise a fix.
BACKGROUND: Volvo 2030B c1998, 2400 hours, standard alternator, digital hour meter in the tacho.
In recent years, charging alarm sounds on startup, need to give some revs to kick start alternator (minor nuisance. Belt checked and seems tight enough. Batteries are not new but perform ok).
PROBLEM: at end of a long day sail (batteries someone discharged, but engine started ok), the hour meter showed no numbers, just a few dashes - and the tacho showed no revs, just twitched to full revs every minute or so. Alternator and engine perform apparently normally. Problem has persisted.
Not sure whether to call Volvo agent, sparky, or is there a fuse that I can replace...?
TIA (thanks in advance)

 

[RichardS]

The need to blip the throttle to start charging is a standard feature with many marine engines and is probably not related to the tacho issue which is probably a poor connection somewhere which manifests itself when the battery voltage is down a bit. Best place to start would probably be at the alternator with a check of all terminals and bullet connections. Undo, clean and re-make them if you have access.

Richard

 

[Carmel2]

On mine there is a very small red light bulb at the back of the taco and when that went I had no read out, that might be a small part of your problem.

 

[Venus1]

Update:
I tested all the connections to the best of my ability, to no avail.
A sparky thought it was a faulty tacho, on the basis that it was getting 12v, and "twitching", but not showing revs. Also the fact that the hour meter had power but wasn't showing hours (which it would normally do even without the engine/alternator running) implied tacho fault - not wiring fault.
Anyway we fitted a new tacho (many beer tokens!) and all is well now. FYI