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Siler Starum's picture
Siler Starum
Last seen: 3 days 16 hours ago
Joined: 4/20/18
Posts: 53
range switch setting tachometer

I replaced my broken tachometer for a new one, delivered through Catalina-Direct.
The new one delivered shows on the ID-plate: 2051 rpm @ 400Hz and a range switch which is set at "B".
However the old broken one shows on the ID-plate: 2797 rpm @ 400Hz. and has no range switch like on the new one.
The range switch on the new tachometer is going from "A" to "E". 
To which position should I set the new tachometer so that I am sure that the revs from the engine are shown correct on the tachometer?

 

Durk Nijdam
S/V "SILER"
Catalina 36MKII - 2001 / hullnr. 2013
Stavoren - Holland

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Durk Nijdam
S/V "SILER"
Catalina 36MKII - 2001 / hullnr. 2013
Stavoren - Holland
Stevenjones's picture
Stevenjones
Last seen: 4 days 16 hours ago
Joined: 6/29/07
Posts: 74

Catalina Direct has an excellent tech help desk -a separate phone number.  I'd suggest calling them. Happy New Year! 

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Steven Jones
C36/375IA FaceBook group administrator
C36/375IA Jib Sheet Editor 2012
Seal Beach, CA, USA
C36 #2164 Maléna  2003 Mk-II SRig/FullK,  Long Beach, CA
stevenjones21@gmail.com
Siler Starum's picture
Siler Starum
Last seen: 3 days 16 hours ago
Joined: 4/20/18
Posts: 53

My question has been answered: information received from CatalinaDirect.

Tachometers are adjusted by our vendor to be approximately correct when installed on an M25XP with standard alternator and pulleys. They can only be exact if calibrated after installation using a mechanical tach or strobe. All other engine installations including other Universal Diesels and Westerbeke engines may require adjustment of the tachometer.
 
A fine calibration potentiometer is under the sticker at the back. It is a delicate electronic device mounted to the far side of the circuit board. A watch maker can successfully adjust it without damaging it or pushing it off of the circuit board. Our experience is that most mechanics are too ham-fisted and will break it every time. If approximately correct isn't accurate enough and you remove the sticker over the calibration screw, the warrantee is void.
 
For Universal M-25, M-25XP, M-25XPB, M-35, M-35B: set "Alternator Range" to "B" then tune with hand tach
 

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Durk Nijdam
S/V "SILER"
Catalina 36MKII - 2001 / hullnr. 2013
Stavoren - Holland
Catboat Willy's picture
Catboat Willy
Last seen: 11 hours 31 min ago
Joined: 12/22/14
Posts: 255

Durk;
Thank you for posting that information. I installed a new tachometer several years ago and had a difficult time figuring out  what position of the switch was the correct one. I wish I had your information at the time. After calibrating the engine with a strobe tach, we found the tachometer to be less than 100 revolutions off and decided that it was not worth fooling with. I was also told that it takes a special screw driver to adjust the screw that lies under the label.
 Happy New Year,
 Bill

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Bill Dolan 1990 Catalina C-36 MKI - Hull #1041  'Williwaw'
Std. Rig, Walk Through, Wing Keel
M35, Oberdorfer Conversion,
Home Waters; Port Charlotte, FL
'You are never out of work if you own a boat'

 
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