Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

I bought a tachometer from eBay for $23 including shipping and what a total junk it was (http://cgi.ebay.com/Tachometer-Hour-meter-2-4-Stroke-Small-Engine-Spark-/120689310104?pt=LH_DefaultDomain_0&hash=item1c19a4b998  I got mine from a different seller and was able to get a full refund but what a junk - you can buy a nice bottle of wine for $20 so don't waste your money on this model.

   It will probably reset by itself with a bat install.  There "reset" printed on the board so worse case those pads could be messed with. It would be nice to have a schematic.  The two big chips are a 7400 series which is a simple D flip flop and probably takes the S1 and S2 inputs.  The other is an 8 bit risc chip.  The data sheet for it is online.  It should have a reset pin which usually is pulled to ground for a reset.

   The back cover comes off easily and the soldering is simple with a pencil tip soldering iron.  I put a short wire on for ground and will put a perminant wire on machines so the meter can be removed easily.   The case is not brittle so easy to drill without cracking or breaking the case.  The back cover also popped off easily with a knife. 

   Mine was advertised as "replaceable battery" and also listed as potted.  It's not potted and there's no batter holder or compartment as I expected.  There's probably a lot of ticked off people who bought the single lead version.

   On a closer look your board and my board are very different.

Why not just ground the shield of the "single" wire?

On the single wire units are a single "wire", no shield.

I did try miniature coax starting a few inches outside the case which did not help.  It would have been better to run the coax shield as the ground inside the meter and tie the other end to the engine but I did  not want to solder the shield in such a tight spot inside the meter.

RF can be very weird.   It might be useful to try an R plug.  It's possibly it might have cured the meter

Messing with the tach's again. The batter crapped out last year so replaced it today so some observations for tach owners like the HM011 types. The back of the case can be pried off with an Exacto knife and the bat unsoldered. The harder part was gluing it back in place to hold the bat to ground which is a very iffy deal as the bat is only pressed onto a ground on the board not attached. It's then held in place with silicone or epoxy. A messy deal with epoxy as it's conductive so a tricky install. Before buying the bat it got tested by putting two 1.5's in series which worked. So an alternative to installing a new bat is getting a dual 1.5 AA holder, run the wires through the case and solder them to the lithium batter post and ground.

    Tach mounted to Murray SS.  Pretty easy...a piece of flat stock drilled and bolted to the carry handle mounted with velcro.  For some reason the response time on this engine is much better than prior use on 7 and 8hp 4 cycle engines.  Hopefully it will catch the sag when running booted rev's and loaded.

If I remember right,  the reset on the board is for awiring of a switch to reset the "hobbs" or hour meter... On some units there is a button built on the case, to reset for maintenance or serviceing needs..

I had the "Tiny-Tach" made unit for 12 or so years before the battery took a dump,  never gave me a lick of problems...   If you are doing repairs or maintenance/ tune work,  there is a nice unit made that is total inductive with no wires...  It has a fast processor and is good to 5 rpm change in speed.. I can't remember the name (sorry)...  but you had to hold it within 1 foot of the plug wire,   it was great of setting the high speed chain saws with the spark plug buried under some air induction cover..

Friiy

Has anyone connected an analog dial tachometer to their snowblower?  I'm asking since these little electronic tach have terrible lag and with small display which makes it difficult to read, wouldn't an large dial tachometer allow you to see it better and to get a feel at what your max torque or HP is occuring?