colonelbob
Junior Member
On the hard at Harrington Harbour North
Posts: 15
Jeanneau Model: 42 DS
Yacht Name: Cher Ami
Home Port: West Point, NY
Country: USA
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Post by colonelbob on Jan 31, 2019 19:30:18 GMT
I've got the notorious erratic tach and disappearing hour meter on the B panel of my 2007 42DS with Yanmar 4JH4E. I have a new VDO tach on hand and ready to install but I don't know how to determine the pulse rate to configure the new tach. I have a TinyTach digital meter down below to determine true RPM. Any advice?
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Post by Mistroma on Jan 31, 2019 23:13:12 GMT
Pulses per revolution depend on the alternator and gearing provided by the pulleys. However, you haven't changed that and therefore pulses per revolution will be unchanged. I know of at least 2 types of VDO tachometer and I have calibration instructions for both. 1) Type fitted with a potentiometer and DIP switches. 2) Type calibrated using a sequence of button presses to adjust figures on LCD display. I have the second type on my 42DS with a 4JH4AE. I uploaded the instructions for this type first as it will almost certainly be the one you need if you are doing a like for like replacement. Click on this link to download itMy notes show that my tachometer is configured for 10.29 pulses per revolution (documentation says this works for 3YM & JH4). There's a huge variation across engines. e.g. 3JH3 & 4JH3 use 116 pulses per revolution. I have also put a link below in case you obtained a different type of tachometer and need different instructions. Click on this link to download it
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Post by Trevor on Feb 1, 2019 8:42:39 GMT
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colonelbob
Junior Member
On the hard at Harrington Harbour North
Posts: 15
Jeanneau Model: 42 DS
Yacht Name: Cher Ami
Home Port: West Point, NY
Country: USA
|
Post by colonelbob on Feb 11, 2019 22:24:11 GMT
Pulses per revolution depend on the alternator and gearing provided by the pulleys. However, you haven't changed that and therefore pulses per revolution will be unchanged. I know of at least 2 types of VDO tachometer and I have calibration instructions for both. 1) Type fitted with a potentiometer and DIP switches. 2) Type calibrated using a sequence of button presses to adjust figures on LCD display. I have the second type on my 42DS with a 4JH4AE. I uploaded the instructions for this type first as it will almost certainly be the one you need if you are doing a like for like replacement. Click on this link to download itMy notes show that my tachometer is configured for 10.29 pulses per revolution (documentation says this works for 3YM & JH4). There's a huge variation across engines. e.g. 3JH3 & 4JH3 use 116 pulses per revolution. I have also put a link below in case you obtained a different type of tachometer and need different instructions. Click on this link to download it
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