erronious tachometer readings

[tomc1]

We have recently purchased a 1983 CD 36 with a Perkins 4-108 engine that is fitted with a Balmar high output alternator The Tachometer reads about double the actual rpm's, it also doesn't have any reading until I reach about 1400 actual rpm's. The tach has no markings to identify it. the back of the tach has 14 dip switches. Does anyone have a similar tach and know how the switches are configured so that I might get the tach to read correctly?

any info would be appreciated

Tom C.

[mgphl52]

Posting a picture of the back of the tach may help. Also check on Cruising Outpost and/or Trawler Forum.