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Posted: Thu May 17, 2007 2:39 pm
by KLAS
ah, i thought that this is only a problem with revs more than 3000, but my Smith didn't react at all connected to TACH OUT, so i just ignored it
will test and report back
and make some pics from the inside of a Smith
Posted: Thu May 17, 2007 2:46 pm
by brentp
Another PDF discussing tachometer modification / troubleshooting. Is the tach Svein reference indeed the same as the Smiths tach you're using? Was there basically one supplier of tachometers for British cars in the 60's?
http://www.engravers.com/tiger/tech/stoa_tech_9904.pdf
Posted: Thu May 17, 2007 3:05 pm
by KLAS
as far as i know Smith was the british manufacturer of instruments.
the one i have here seems to be what i would call "moving coil", a steel ring with a small coil that moves on it, some electronics, made in 1984
2 low quality pics
Posted: Thu May 17, 2007 3:11 pm
by brentp
Interesting. I was a few decades off!
I wonder how old the basic design is? The face of the tach looks very similar to what is shown in the referenced PDF.
EDIT: Another link off of the same page, discussing Smiths tachs in MGs and volvos. My uncle's 1973 1800ES volvo apparently uses the same tach...
http://members.shaw.ca/tsmit/tachmod/tach_other.html
Posted: Sat May 19, 2007 6:42 pm
by KLAS
minor update: removed the Zener, tacho will not work at all. just for fun i played with 3 different Zener, 5.1, 12 and 24 volt. 12V works as expected, up to 3000RPM than drops out, 24V worked the same but the needle was swinging a bit up and down, the 5.1V didn't work at all like no Zener was fitted
tomorrow i will test the PIP line
Posted: Tue May 22, 2007 2:22 pm
by KLAS
finally i tested the PIP line and IT WORKS!!!!!
not tested with max revs of 6500, but it went over 4500 without problems
for now i would say if you have a Smith "moving coil" tach use PIP as trigger
thanks to MartinM and his theory
Posted: Tue May 22, 2007 3:10 pm
by MartinM
Excellent news so far
Very keen to know that it goes all the way to the red line! Report back....
Martin
Posted: Tue May 22, 2007 3:38 pm
by brentp
Great to hear you have it working! PaulF mentioned in another thread that he has been driving his tach using PIP for some time now, so that's further validation on the technique.
http://www.autosportlabs.org/viewtopic.php?t=1231
Will add this info to the installation & troubleshooting guide for certain.
Thanks to Martin, Paul and others for their contribution!
Posted: Tue May 22, 2007 4:52 pm
by mikaking
Just to let you know i put a wire from the PIP signal to my smiths and hey presto works a treat as well. Mine reached the red line 6000rpm. Thanks MartinM.
Posted: Tue May 22, 2007 5:50 pm
by MartinM
Invoices are on their way...