Test the timing triggers on a johnson

[camalot]

Hi Guy's

I did a search and didn't come up with anything.

The outboard in questions is a Johnson 225 around 1990, I've lost one bank. Check the usual places shift interrupter, coils, earths.

So I'm thinking it could be either power pack or trigger, is it possible to check the timing trigger with a multimeter?

Thanks in advance.

Paul

 

[metriccrescentwrench]

Re: Test the timing triggers on a johnson

So I'm thinking it could be either power pack or trigger, is it possible to check the timing trigger with a multimeter?

Yes, BUT..... you'll need a DVA adapter. What that does is captures the peak of the voltage pulse which happens for just a fraction of a millisecond on each revolution. If you're handy with a soldering iron you can make one out of common components, you should be able to search around just a little bit and find a schematic. OR you can buy one for 30 or 40 dollars.

 

[Chris1956]

Re: Test the timing triggers on a johnson

Paul, That motor may have a shift assist switch which kills spark to 1/2 the motor when you shift. Sometimes they stick. Also, that motor likely has the SLOW system which kills spark to 1/2 the motor if it thinks the motor is overheating. You might check these.

 

[boobie]

Re: Test the timing triggers on a johnson

When the mtr goes into SLOW it stumbles all the cyl's.

 

[daselbee]

Re: Test the timing triggers on a johnson

If you use a mulitmeter set on ohms to test the timer base, you will get very inconsistent results.
Results even vary from meter to meter.
The reason is that the low bias current used in today's meters will not forward bias the internal electronics of the timer base.
You get weird results.

Regarding the DVA comment.....DVA adapters typically have a diode in series......so if you try to measure any voltage that is less than
.7 volts, you will be unsuccessful.

I have not been able to measure the output pulses of a timer base with my home made DVA adapter, but it works fine on the higher voltages output from the pack to the coils.

You may be successful with a high end Fluke peak reading meter....a meter that is not so crude a circuit as these home made adapters.

 

[durban]

Re: Test the timing triggers on a johnson

a very easy way is get a 5 -9v neon globe make sure it got gas in like the ones they use in a timing light , cause they have a special gas in them , thats why every time the current comes in to the globe it lite up the wire inside the globe & the gas in it does something too , connect one wire to the common & the other one earth , easier this way , there is not much current that go through hall sensors . cheers

 

[camalot]

Re: Test the timing triggers on a johnson

Thanks guys

Interesting stuff, so a home hade DVA may struggle to read the signal. So would anyone know of a DVA reader that would/does work, I don't mind spending some cash if they work lol.

Many thanks for the help.

Paul

 

[durban]

Re: Test the timing triggers on a johnson

a good 1 reads Milli amps

 

[tx1961whaler]

Re: Test the timing triggers on a johnson

Thanks guys

Interesting stuff, so a home hade DVA may struggle to read the signal. So would anyone know of a DVA reader that would/does work, I don't mind spending some cash if they work lol.
Paul

The times I actually measured the timer base voltage waveforms I used an oscilloscope. I do realize that not everyone has one lying around....but they do make some pretty inexpensive 75 MHz USB "Scopes" that would capture a 0.5 Volt signal. There are also new "real" scopes on ebay for about 300 bucks that are returnable....but don't expect a name brand new for that price. There are guaranteed used Teks on there for 100 bucks.

 

[Chris1956]

Re: Test the timing triggers on a johnson

Paul, On my '98 Johnny 150HPV6, the shift assist switch kills spark to cylinders 1,3,5. Is that what you are seeing?

 

[camalot]

Re: Test the timing triggers on a johnson

The times I actually measured the timer base voltage waveforms I used an oscilloscope. I do realize that not everyone has one lying around....but they do make some pretty inexpensive 75 MHz USB "Scopes" that would capture a 0.5 Volt signal. There are also new "real" scopes on ebay for about 300 bucks that are returnable....but don't expect a name brand new for that price. There are guaranteed used Teks on there for 100 bucks.

Thanks for that I did not realise that a oscilloscope was so cheap (or well priced lol)

 

[camalot]

Re: Test the timing triggers on a johnson

Paul, On my '98 Johnny 150HPV6, the shift assist switch kills spark to cylinders 1,3,5. Is that what you are seeing?

Hi

I did check the interrupter switch, open circuit then it closes as you shift so thats working ok.

 

[camalot]

Re: Test the timing triggers on a johnson

I do have a multi meter with a AC function on it, I checked a 9.9 Johnson and using the "peak hold" funtion I get .7V so I will try that tomorrow on the 225 and post the results.

Thanks for the help guys

Paul

 

[camalot]

Re: Test the timing triggers on a johnson

Well I got down the bottom of what is wrong with this motor.
It became obvious that a "run of the mill DMM" could NOT capture the sine spikes needed to measure things. So I made a DVA and did some testing.

It turned out to be the stator one side showed 179v and the other only 35v bingo. I then tested the triggers to see if the DVA would work reading low "v" sines.
Well it worked like a charm, "com" lead connected to the white or white/black and checked the green,blue and purple trigger wires. The average reading was .6v.

I also did a quick and dirty check and plugged the good stator side power into the dead bank, attached a strobe light and cranked motor, the strobe fired.

I have just found out that the OEM stators are no longer available lol.

Thanks for your help guy,s

Paul