Help on "tachometer amplifier"?

[jgresham75]

Bought my 99 Wellcraft used. Engine runs fine but missing parts and I am trying to get back to original. Tach doesn't work but found out tach sending wire not connected to coil. I purchased a repair manual to find out how to connect. The electrical diagram shows a "thingy" (this being a technical term) called "tachometer amplifier" in line right before the coil. My used boat did not come with it, thus the wire was not connected. While I can understand what it may do by the name, I can't seem to find any info on it. I have searched internet, this forum, and volvo's site but no luck on any info. Even tried "ignition amplifier" but that seems like something else.

Can anyone give help on where can I find one or does it need one? Any extra explanations on this item would be helpful. I have search stores and no one seems to carry one of these. I do not want connect the tach wire directly to coil unless I am confident I will not screw up something. Thus I am asking for your help.

By the way, the wiring manual shows no amplifier on the 98 model engine with similar wiring setup.

Thank you in advance for your help.

 

[Windykid]

Re: Help on "tachometer amplifier"?

I do not have any amplifier on my coil. All my tach's have been hooked up directly to the coil "-" neg side.

 

[Capt Ken]

Re: Help on "tachometer amplifier"?

Never heard of one in modern days. Old Sun tach's back in the 60's required one and it was a big box that mounted under the hood.

 

[Don S]

Re: Help on "tachometer amplifier"?

Seems the WT models 5.0 & 5.7 GL and GS from Volvo are the only models that used a tach amplifier. Why I don't know. I guess I'll have to do a little research and see if I csn find out a "WHY" it was there on that model and not others that used the Prestolite BID distributors. It is hooked into the gray tach wire and to ground. Maybe Volvo used a new type tach that year. I'll see what I can find.

 

[drrm123]

Re: Help on "tachometer amplifier"?

What's a SUN tach? The only company i've hear of is Autometer! I'm just kidding I remember those tachs.

 

[chiefalen]

Re: Help on "tachometer amplifier"?

Welcome aboard !

I stay away from volvo posts.

But may i say; it is a fine package you purchased. A wise choice.

Use it in good health !

 

[Don S]

Re: Help on "tachometer amplifier"?

I can't find anything about it other than it was an option. I would bet if you hook up the gray wire to the minus side of the coil, your tach will work just fine.

 

[Capt Ken]

Re: Help on "tachometer amplifier"?

I wonder could it have had anything to do with maybe dual station tach's? Maybe the amp was to ensure enough signal to drive two tach's if needed.

 

[Don S]

Re: Help on "tachometer amplifier"?

It probably had something to do with it Ken, but I doubt he has a FB on his 200S Here is a picture I found of a 200S (see below)
My guess is he never had one installed. A tack with an internal short will cause the engine not to run. If he then went looking in the service manual, he probably found the amp in the wiring diagrams and then went looking for the part.

My suggestion would be to hook the gray wire to the coil - terminal and see if it runs. If it does and the tach works. you are good to go. If it won't start, unhook that wire. Then if it does start, you need a new tach, not a tach amplifier.